Vehicle  Platforms

Military platforms (if you can get them), are usually superior in their robustness and ground clearances and can go places that your typical motorhomes and domestic 4x4 vehicles cannot. Most motorhomes or coaches, are typically built on a medium or light truck chassis and this usually confines them to the black stuff or well graded dry dirt roads. The times that I have spent working on large bus sized motorhomes from the USA shown me that they are usually on a standard truck chassis. Most of these vehicles as well as the domestic 4x4s vehicles (even my diesel Land Rover Disco) are lucky to have barely 200mm of diff clearance. That's not going to cut it under some less than ideal situations that one might come across in the Australian bush. Even if you are as conservative and risk averse as me, when travelling across Australia the most likely issue (aside from potentially crashing into the odd bullock, camel or other wildlife), is coming across a  flooded or washed out track or creek bed crossing. This is when the Unimog comes into its own (though, it is heavy and can still easily get bogged with the original ADF narrow wheels).

As in the case with the USA, the Australian Defence Force (ADF), is busy divesting itself of life expired fleet and upgrading with faster lighter more agile multi-function mine resistant vehicles. The US have some very nice vehicles being auctioned also, but I found out that only US citizens are allowed to buy and export them. So in Australia, its easier to just buy local. Not for 30 years has such a good opportunity presented itself for ex-military vehicles in Australia. I am very glad that the government took the stance to sell locally and not ship them off to developing countries (as was one option being considered).

One should go into this with ones eyes open. Some of the downsides to buying a life expired military vehicle such as the Unimog are that:

• parts can be difficult or impossible to obtain (as its often a bespoke build for the particular country of use). 
• top speed is often 90/100km/h. They are geared low (designed for torque, not speed). 
• they are designed to be austere, very functional and not necessarily comfortable. 
• engineering certificates may be required depending on the type of modifications (eg; changing wheel type, exhaust direction, adding fuel tank, etc),
• parts are generally expensive compared to your run-of-the-mill Toyota 4x4,
• a 30 plus year old vehicle is likely to have some wear in the overall drive train, and
• the drive train noise level is a lot higher than your average car.

According to the 2011 Industry Briefing Disposal Strategy report (confidential) within ADF, they were expecting to sell 2430 vehicles (not all suitable for public on road use). The actual number is far less (certainly less than 2,000) making them a unique collectors vehicle.

A useful source of information when inspecting (if you get the opportunity)the trucks pre-purchase at auction, is the vehicles 'Service Record Book' (if it has one). At the time I purchased my vehicle I was not aware that also, there was a recent 'Technical Inspection Report' slipped into my book which details some identified problems. At the very least, its worth reading this brief report if you don't have time to scan the entire life history of the vehicle. 

Some of the ADF variants are shown below (source: ADF public domain Maintenance Manuals):

It is highly unlikely that some of the more weird variants (radar etc), will ever come on the market but AFM is tasked with the job of 'de-militarising' all vehicles before they go to auction.  As can be noted below, military vehicles are very practical and usually very busy looking (the aesthetics are not so important for military vehicles). So I don't feel too badly about mine turning out busy also. The ones shown below, are both recovery vehicles, the one on the left is a MAN heavy recovery and the one on the right is the Unimog medium recovery. This 6x6 recovery Unimog (as shown below) provides for extra length, but practicality took hold and I ended up purchasing the more common UL1700L/38 flat bed. In any case, at the time, the ADF 6x6 recovery vehicles were classified as 'protected' and not supposed to be sold for some time yet. As at 2022, they were being actioned off and fetching around $75k plus, each. 

Unimog 435 Series  General info

Unimog is an acronym derived from the German “UNIversal. MOtor Gerat“ (UNI-MO-G), or all-purpose machine or 'Universal Machine'. Its a slow moving vehicle (developed from a tractor), but very strong, the military version having a militarized commercial engine and drive train. The older square cab series used by the ADF is known as the 435 series. The U1700 is a medium battlefield truck. Any parts and materials I nominate herein are for the Australian military U1700 version (in my case the U1700L/38 / UL1700L) and they may not suit any other version and its up to you to check the validity yourself anyway. I suspect that most of the military U1700L's in Australia are essentially the same, with various options such as: winch, tyres, tip tray, flat tray, crane, radar disk, shelter cubicle etc.  There are even a small number of dual cabs. They apparently all came out of the same Victorian Benz Daimler factory (as I understand).

At a time when most military light truck makers adopted independent suspension (the military sees an advantage in independent suspension, because a land mine can blow off one wheel and the vehicle may still be drivable?) – the Unimog stuck with live axles, because of their superior wheel travel and tyre contact on highly uneven surfaces.   Of interesting note: the modern Unimog (likely with some modifications and a set of working gears added) has been used to shunt up to 1000 tonne trains around rail yards (cheaper than buying a shunting locomotive) so you can get an appreciation of the low down torque available (with mods) and the robustness of the chassis and drivetrain. But it will be moving very slowly with a big lump of concrete on the back to get the rail traction needed.

Basic data for my derivative, U1700L cargo:

• Manufacturer Daimler-Benz
• Australia Army second line transport (medium size)
• Max load carried is 5 tonnes
• Ground clearance 460mm
• Mass unladen 6.8 tonne
• Maximum total loading 12 tonne
• Maximum legal loading with trailer 21 to 24 tonne
• Fording depth 1.2m
• Turning circle 19.6m
• Angle of approach 39 degrees
• Maximum gradient 60 degrees?
• Gross combination 24.5 tonne
• Fuel (standard arrangement) 25L/100km
• Engine OM 353.939 (OM 352a)
• Automatic load dependent brake
• Air brakes
• 4 wheel disc
• Voltage 24V
• Trailer socket NATO 12-pin
• Winch Werner 62kN. Cable length 30m x 14mm Steel. Note:Synthetic cord is NOT suited (don't even think of trying it, I did and it was an expensive lesson).

Some of the refurbishment jobs:

• Winch refurbished, regreased/oiled, new winch cable. 
• Rear park brake actuators refurbished. 
• Air tanks and air system refurbished (tanks coated inside with epoxy sealer).
• Original seats removed, adapter bases made & new air ride seats installed. 
• Cabin roof lining and internal replaced. 
• Added auto drier/filter kit to air system.
• Front guards remade.
• Rear guards remade. 
• Freight liner steering wheel and hub. 
• Straightened front bumper. 
• Fix pin holes in roof and passenger door by TIG welding. 
• Soundproofed underside and inside. 
• Stripped out cab and doors and replace most rubbers. 
• Repaint cab (inside and out). 
• Repainted underside of vehicle chassis (drab olive). . 
• Installed long range fuel tanks (316 mirror polished from F650) including piping and level sensors etc. 
• Relocated batteries under bonnet. 
• Fitted custom tray head board. 
• Fitted front underside front protection crash bar. 
• Canvas covers for cab air conditioner, masthead flood lights, spare wheel, crane, rear folding steps, etc. 
• Replaced all engine belts and idler pulleys and associated bearings. 
• Replaced all filters. 
• Tubed up new low pressure air systems  (for: air horns, seats, tyres and telescopic mast). 
• New turbo. 
• Added Turbo intercooler. 
• Replaced exhaust with stainless: new muffler and vertical stainless stack. 
• Added bracket for tilting the cab safely (using hydraulic ram). 
• Added custom tool boxes.
• Replaced cab access steps with 316 stainless. 
• Added 12m telescopic pneumatic lighting mast to barge board on drivers side. 
• Added engine / drive train: monitoring/warning systems. 
• Added cabin air conditioning (compressor under bonnet). 
• Headlights refurbished & upgraded.
• Added remote door locking modules. 
• Added security alarm module.
• Added video and data logger accident recorder.
• Camper module installed. 
• Added grey water and hand wash water tanks.
• Added crane for spare wheel.
• Spare alloy wheel purchased and secured. 
• Added 3 spot lights.
• Added large white storage box.
• Added 300l bulk drinking water tank.
• Added front guards extension kits.
• Refurbished exhaust brake butterfly valve.

Progress Photos

9th Dec 2020

Took it out for a run, down below Wollongong this morning (a warm day) so that the certifying Engineer could inspect my mods (fuel tanks, wheels, exhaust, etc). 

Stopped regularly and checked diff's, hub's, gearbox temps, etc, all were good. Engine monitoring and tyre monitoring systems all in the green. 

It will sit at 90Km/h comfortably only on the flat at 2600RPM (almost flat chat, does not like running much higher). It seems to refer sitting on 80km/hr at about 2300RPM. Max I could get out of the new stock turbo (with intercooler) was ~0.77 Bar and exhaust temp never went above 500C (lots of steep hills between Wollongong and Sydney). Exhaust brake worked well when descending Mount Kiera. 

Note that the rear chevrons in the above photo on the rear of the trayare not legal (cannot have them all sloping in one direction). 

Mundi-Mundi Trip April 2022

First long run. Sydney / Mundi Mundi plains north of Silverton (about 3000km round trip).  On the way out, along the Silverton Highway, it bucketed down and all the regions water ways were swollen and flooded and many of the dips in the road (being flood water gullies), were also flooded with some silted up deep with soft mud making them impassable for all normal 4x4's. We just sailed through without a worry, due to the high clearance.

Regular stops and checking of portals, diffs and transmission showed all in excellent temperature range during the 3 week trip. On the good condition flat roads, the vehicle was comfortable sitting on 90km/hr at 2600RPM. 

Whilst I was passing through Broken Hill area on the way homeI wondered if the drive shaft universals might be contributing to noise, so I phoned Mog Central who freighed a pair out, and a day later they were installed (local company did the job) before I left Broken Hill. 

Unfortunately 5th and 6th selection started to get more difficult on the way back near Bathurst. I did not want to risk damage, so I had it transported the rest of the way home over the mountains on a low loader (see last photo below).

Transmission Overhaul 2022

5th and 6th were getting increasingly difficult to select, despite using the very best synthetic 500,000km transmission oil available.  It was time to fix it. Total kilometrage: 114,400 (previous speedo) plus 88,765 (on new speedo) = 203,165km. 

The transmission consists of transfer case and gearbox. There is one impellor (input shaft) to transfer case and two output shafts (front and to rear). The gearbox and the transfer case are separate items bolted together. The gearbox can be easily removed separately from the transfer case. 

None of these jobs is for the faint hearted, and should be left to the professionals, as the average joe could do themselves a very serious injury, or worse.

Gearbox removal - June 2022

There appears to be only a few companies that can rebuild (exchange) gearbox in Australia (Unidan and MogCentral, to name a couple). 

Gear Selector Lever: Disconnection of the gear selector horizontal shaft is achieved by loosening off the two clamp bolts on the universal joint and which just unscrews by hand. One might need to remove the bolt just under the gear lever itself, also. When reconnecting the gear lever horizontal shaft and its universal joint, its not really a critical adjustment, main thing is that the gear lever does not interfere with anything inside the cab and that you can select all gears. Remember that, you need to select 3 or 4 before you can change to 5 and 6 and visa versa (cannot jump 2 gears at a time).

Transmission input (propeller) shaft:  I used the starter motor to rotate the drive shaft (gearbox in neutral) so I could progressively get access all 4 bolts on the transmission input shaft flange (15mm ring spanner). A better option is to have someone hold in the clutch so that one can rotate the engine propeller shaft by hand.  I had to grind a little off the thickness of the ring spanner to get at two of the bolts. BIG HINT: It is a good idea to mark (paint pen) the position of the two flanges before disconnecting. This is because the 4 holes are not always in an exact symmetrical placement. 

Removing the Transmission:  Photos show a custom ply cradle to support the gearbox, on top of the red scissor lift table (500kg rating). These photos are before I secured the box to the ply cradle using ratchet straps.  Note; when removing just the gearbox, the drivers side of the transfer case is no longer supported. Thus, the transfer case needs to be independently supported with a jack stand or such.

Out of interest, I read through my ADF supplied service book history and noted:

• 'Contract Maintenance Sec. F.M. Mech. DNSDC' overhauled the transmission at ~114,000km in 1998.
• Transfield Services rebushed gear selector due 'to crunching in 6th' at 158,872km in 2005, and its the same problem I am having?

Warning, this vintage of original gaskets will likely contain asbestos.  It's 26th August 2022. Gearbox is out and crated up ready to be sent off for a rebuild/exchange.

Photo 1: Front end cover plate removed. Photo 2: Main front thrust bearing observed behind cover plate. Note: My box had two end float shims (1mm and 1.8mm) on the font side (behind the main cover plate). The ADF overhauled the transmission at 114,000km and engraved the word 'Bolt' on the thrust washer so it goes back in the right way again.  Photo 3: Red scissor lift table . Yellow jack stand is supporting transfer case (this is important to keep in place all the time). Photos 4 to 7: Winching the gearbox backwards. Photos 8 to 9: Gearbox clear of transfer case. Photo 10: View into transfer case after gearbox removed. The synchroniser disk needed levering off the transfer case gently and it comes off together with the transfer case input gear and two thrust bearings (caution, its heavy). Photo 11: Transfer case input gear viewed from rear of vehicle (before being pulled out). Photos 12 to 13: View from front of vehicle before transfer case input gear is removed (from rear side). Photo 14:  View into gearbox after being removed from transfer case. Photos 15 to 16: Lowering of the gearbox once the long studs are clear of the transfer case. Photo 17: Gearbox is wheeled out from under the chassis. Photo 18: Gearbox is lifted by engine crane, ready to be plastic wrapped and crated up.

Note:  Once the case has been opened up it is important to immediately seal everything in plastic so that no dust can enter. Everything needs to be kept surgically clean, as one spec of grit can destroy a bearing quickly.

Further:

• Photo 1: The top centre circled hole is an oil plug that does not need to be removed. The top right circled shows two bolts that must not be removed.
• Photo 2: The gearbox is winched backwards using the yellow strap. Note: We first fitted the nuts to the long bolts and then gently tapped the bolts in order to crack the gasket seal. Warning, this vintage of gaskets will likely contain asbestos.
• Photo 3: The synchroniser disk that had to be gently levered from the rear of the transfer case (once the gearbox is out of the way). Behind it is the transfer case input gear which has a tapered roller bearing each side of it (see photo 5 below). The transfer case input gear can then be pulled out the rear of the transfer case with a bit of wobbling and gentle tapping with a lump of (clean) wood. 
• Photo 4: Synchroniser disk and transfer case input gear.
• Photo 5: the transfer case input gear with front main tapered roller bearing each side looks in perfect condition.
• Photos 6 to 7: Show some worn leading edges on toothed selector rings associated with the high low range selector.
• Photo 8: Some heat issues associated with the above toothed rings.
• Photo 9: Shows the ring that has heat marks.
• Photo 10: Shows where the ring comes from and wear marks behind it.
• Photo 11: Exposed gears and internal areas were plastic bagged and thecrate lined with builders plastic. 

Re-installing the Gearbox - December 2022

There are two different gaskets needed, one each side of the transfer case (a rear and a front). They look similar. 

Once you have fitted up the gearbox and before fitting the transfer case end cover, the front main tapered roller bearing need to be checked for the correct axial end-float. The ADF manual states end-float 0.04 to 0.08mm (see table 17 of manual G604-1). This is achieved by fitting shim rings (available from Mercedes etc) to the outer ring. The Repair Parts Scale gives a list of the various thickness shims and the Mercedes part numbers. I fitted a cross bar (temporarily) to load up the outer ring. I also temporarily tightened half a dozen nuts around the periphery to compress the rear gasket and then checked the gap on opposing sides using feeler gauges in 0.01mm increment. The gasket was 0.28mm thick. By this information, I worked out the available end-float. A micrometer is a recommended tool. I was lucky, as my existing shims got me to just within the required tolerance.

The ADF manual states 75Nm for the M12 bolts and nuts around the end cover.

The front main tapered roller bearing supplied, was Timken part 98.17.0083

The front gasket supplied was MB part A4372610880

The rear gasket supplied was MB part A4372610580

I used non hardening Loctite gasket sealant No. 3 on the two big gaskets for the gear box and Blue thread locker (medium) for the bolts where its specified and Loctite silver stick anti-seize for bolts I expect to undo again, and plumbers liquid sealant for air fitting threads.

Setting up: I suggest marking the air hoses between the shift cylinder and the air relay ports before disconnecting. I found that whilst it was possible to pull the high/low lever back with a satisfying click, I could not push it forward by hand. I had thought that I should have been able to do this and was concerned, but a forum member explained that it needed the shift cylinder at proper air pressure to do this. After building up proper pressure, the shift cylinder did push the lever forward ok, but it would not pull it back. I found that my control relay was leaking, and stuck on the forward port. I disassembled the pneumatic relay and found the black pin in the center (see photos below) was stuck (bit of corrosion I suspect). I re-greased, reassembled and refitted. The shift cylinder stroke also needs to be set according to the manual.

Note:When testing with the gear lever in the cab, remember that you need to select 3 or 4 before you can change to 5 and 6 and visa versa (you cannot jump 2 gears at a time).

Greasing Nylon output shafts nylon shells - June 2022

Whilst I had the assistance of the mechanical engineer for a few days, I decided to grease the ball joints nylon shells.

Some people have complained of a groaning noise when they are negotiating rough terrain at low speed. Its often simply that the ball joints and plastic shells simply re-greasing.  

Rear Drive Shaft:  One needs to disconnect the torque tube to get access to the drive shaft flanges. In order to get access to the torque tube casting bolt heads, the rear rubber cover first needs to be loosened and then slid backwards. I wrapped a chain around the rear torque tube up to the tray frame so that it could not drop too far (don't use rope as it will stretch). I used a 4 tonne steel cable ratchet winch with chain attached to the rear of the vehicle to pull the torque tube backwards. I used a jack to be able to move the tube up and down a bit so that the drive shaft flange would pull back without dropping. I progressively loosened the torque tube bolts, winching it back a little each time, and did this a few times until the long bolts came free and then pushed the large cover casting back out of the way then slipped a piece of timber into the gap to ensure that the gap cannot close up whilst I am accessing the 4 drive flange bolts inside with my fingers.  Accessing the 19mm head bolts on the drive flange was a difficult job. 

VERY IMPORTANT: Remember to mark (with a paint pen) the position of the flanges before you separate them fully (see reasons further above). I had to cut down the length of a ring spanner to be able to get it into position to rotate it enough (one spanner notch at a time). Needed a range of different offset ring spanners.  Ideally, I would be able to jack up one wheel, release its park brake, and rotate it, to align the flange bolts vertically (but there would be some risk of vehicle moving ). I also placed a stand under the tube to help keep it up (belts and braces). Whilst the manual quotes torque settings to do the drive flange bolts up again, I'm not going to be able to get a torque wrench in there, so I'm going to tighten them up based on how tight they were originally and using experience (they were quite tight, all requiring a lump hammer to tap the ring spanner to undo them). There will be shim rings and a split nylon shell inside. I reused the same shims and shells (I marked them so I knew the front from the back sets). When reassembling, you need to grease up the shells liberally (with the right grease).

Front Drive Shaft:  Same process as the rear tube. In order to get access to the torque tube casting bolt heads, the front rubber cover has to be removed.  Chained up the front tube to stop it dropping.  I used a 4 tonne ratchet winch and jacked up the front wheels to allow them to move freely, and it made a difference. I was barely able to move the tube, but I managed to open a gap just big enough to get access. Best to place something in there to stop it closing on your fingers. 

After I removed the two half shells, I used a pneumatic die grinder tool with ball tip, to put some shallow scalloped depressions in the shells so as to retain a bit of grease. I used a pneumatic grease gun with the nipple fitting removed from the end of the hose, so I could poke it up inside and squirt grease in.

Cab Tilt System

I had a steel adapter bracket (shown in brown) made to fit a standard 600mm 8 tonne air operated hydraulic ram (shown in blue) to the lower pivot point. Make sure to ensure manual pump handle does not foul anything and the control valve is accessible. This arrangement only takes the cab up to about 30 degrees but this is sufficient to do most work (short of removal of the engine). It's also good for me, as it is not so high that the steering shaft pops out from its telescopic socket, as its a two person job to align it for lowering the cab and I don't have a helper.  I don't use a safety cable, as the cab can never exceed the rams extension limit. But it is VERY important to have something (a strong brace) to stop the cab dropping down. I fitted a safety brace (as shown in yellow), rated at about 12 tonnes. I also put timber chocks in place (belts and braces approach).

The price of the workshop proper ram tool kit runs into the thousands, so this option is much cheaper at about $150 odd dollars (if you make the bracket yourself) if you just want to tilt the cab enough for minor maintenance.

Warning: The use of a ram on one side only, twists the cabin on its front two pivots. This is due to the angle that the ram push's (forward and upward). This is not such a problem when lifting the cab. However, it can be a problemwhen lowering. I find that I have to prop up the drivers side of the pivot saddle (the saddle supports the two rear cabin rubber mounts) so that when lowering the cabin, the edge of the opening in the cabin floor does not strike the parking brake lever.  Also, you will likely find (as I do) that due to the twist in the cabin, the passenger side rubber cab mounts and bolts will not drop into place. To enable this, you will likely need a cable winch to drag the passenger side backwards as you lower the final distance or even after lowering. In my case its often about 30mm offset. I winch off the rear axle until the cabin drops into place. The better way is to raise/lower dead centre of the cabin from the fitting on the centre rear wall so that the cab does not temporarily twist out of shape (but you need an overhead beam).  Put simply, its a nightmare to lower the cabin from one side only, due to the temporary twisting out of shape.

Wheels

In Australia, a wheel comprises a rim and a tyre. The rim is not the wheel.

Tools needed: In my case the stud torque is 400 to 450Nm, so I had to find a reasonable price 3/4" torque wrench up to 500Nm and an impact socket set to suit. Good 1m long 3/4" torque wrenches seem to vary from ~A$185 to well over A$1,000.  I found I could not budge the original wheel nuts even with a 1m extension pipe. Probably another good reason to replace both the studs and nuts, as someone had waaaay over-tightened them. I had to buy a torque multiplier tool to undo most of them. If retaining the original wheel studs/nuts, the threads will likely be caked up with oil and grit. One can clean the threads (both the nuts and the studs) with petrol and a brush and compressed air dry them. They should then run up easily by hand using a drop of light machine oil.

I have to say that the standard steel military wheels are very likely indestructible and very practical. But I just don't like the look of them and the standard tyres are too narrow (easy to get bogged).  Note: when selecting rims and tyres the national heavy vehicle regulations limit how much change in offset is permitted without an engineering assessment and certificate.  Note; overall vehicle width in Australia must not exceed 2.5m. 

There are lots of rim offsets available. Hutchinson alloy rims for example, come in two pieces, both parts have different numbers and need to pair up not to exceed the 2.5m vehicle width rule. You need to do your homework when buying them. Companies like Mog Central and Unidan have already done this same homework and can supply wheels that comply.

When considering upgrading to the wider tyres and alloy rims compared to the more common 12 or 13" tyre width on the ex ADF Unimog 435 series, the following additional issues will need to be considered:

• Weight. Will you be able to change a wheel by yourself?
• Longer wheel studs are needed if you change from steel to alloy rims
• Different nuts are required (two piece), if you change from steel to alloy rims
• Depending on new rim offset etc, one might need a chassis lift (either fit pucks at top of existing springs or replace springs with longer springs) and/or Cab lift. Wheel guards to be extended out (either new guards or extend existing guards as I did)
• If different tyre diameter, you should check your speedo and may need to get it corrected. My truck engineer advised that this is a necessity. Luckily for me, my speedo was reading slightly in error previously, and the larger diameter tyres actually brought it into the correct range.
• Tyre may drag on mud guard at full lock (mine did). This likely means getting the front guards modified or raising the cab or body.
• Engineering compliance certificate is needed if changing wheel type, (as well as when exhaust system, fuel tanks, seats, etc).

Tyres

Tyres can be very expensive and difficult to obtain in a hurry. If however you look after them, I am advised that they can last a long time. Aside from age, UV damage and loss of volatile organics is something one needs to be aware of. You can extend the life by keeping the sun off the tyres when in storage.

The standard ADF tyres here are ~46" diameter and G rated so don't expect to go racing with them. In fact if the gear ratio is changed, one could theoretically exceed the tyre speed rating? The U1750L (typically for the Airforce) has 365/85R20 / 13R20 (13" wide) tyres and the U1700L (typically for the Army) has 12R20 (12" wide) tyres. According to an Army friend, the 12" wide tyres are a regular problem in some situations as they can easily bog the vehicle. The 13" are a little more useful but still not ideal for this weight truck off road. The 6x6 recovery version (U2450L) however, is fitted with the wider 14" tyres as standard i.e.395/85R20.  Note: According to a senior army source, the reason for the three tyre widths is that the Army simply did not want to spend the extra money on wider tyres for all vehicles, and so decided on the thinner cheaper tyres for the majority of the vehicles.  

I'm running the Michelin 395/85R20 XZL Radial. The Michelin engineers are (as to be expected), very conservative (risk averse). Their web site specification sheet (2018/2019) for this 'X Force' tyre,  states (max: load and pressure), but do your own homework for pressures:

• Road                   5.6T /tyre    max 120psi
• Cross country   3.65T/tyre   max 52psi
• Sand/Mud         3.65T/tyre   max 30psi

These are for the tyre loads shown. The specification table does not distinguish for unladen nor for run flat/bead lock options. The local salesman told me minimum pressure was 87psi and would not change his story despite my telling him my tyre loads are only about 2.5T.

Anecdotal evidence from forum members seem to indicate one can go as low as 20psi in the sand (but they probably don't have the run-flats)? I've initially set mine to 75psi for use on the tar. The lowest I'm going to risk as a general rule, is 30psi because I suspect that I would be running on the run-flat at 20psi.

Rims

The Australian military Unimog wheels are 10 stud 20" with 334mm/335mm wheel bolt centres. The army U1700L steel rim for example, is about 8.5" wide. My Hutchinson alloy rims are  10" width. The Australian military Unimogs apparently mostly have steel split rims with a sprung ring.  When changing tyres with a ring, this style of split rim can be very dangerous if you do not know what you are doing and a safety cage may be  required around the wheel. Not many repair shops like to, or will, work on them (so that's a clue straight away). Also, I note that the bolts stick out and the wheel nuts are more exposed to being damaged on rocks due to the steel rim profile. So far I have not been able to find heavy duty wheel nut protectors (they all seem to be decorative type). 

For Hutchinson alloy rims, I have fitted wheel separators (thin 1mm plastic discs) which isolate the inside face of the rim and hub allowing for very minor imperfections and stopping the two getting stuck together due to corrosion and sticking paint.

Run flats & bead locks

When the tyre pressure has been reduced for soft surfaces, sand can enter around the bead and cause the tyre to leak, the tyre can come off the rim due to distortion and/or the tyre can spin on the rim. Bead-locks allow for low pressure travelling (sand etc) thus reducing the chances of a tyre slipping or coming off the rim. For some wheels, if you don't have the combined run-flat/bead-locks (or don't want them), alternatively bead-lock only rings can be fitted inside the tyre.  

Some military wheels (MRAP) from the US come with the combined 'run-flat/beadlock' inserts.  The run-flat in the MRAP wheel is designed (so I am advised) so that the wheel can be run at up to 50 km/hr for a distance of up to 50 km while the tyre is flat (I imagine there would not be much of it left after doing that). However, if the lube has dried out, the tyre will be damaged well before the above speed and distance values are achieved (and probably on fire). I was considering for a long time as to whether I should remove the run-flats. But after recently talking to a tyre expert , I have come to understand that the main advantages are that:

• if you get a blow-out at highway speed, you are much more likely to have a better chance of keeping control of the vehicle whilst pulling over.  This is because the tyre cannot delate to 100% (see my photo further on), so its effectively still kept up (to some extent) by the solid donut rubber run-flat inside.
• if you get a flat in an awkward location such as a river bed or sand dune,  the run-flats allow you to drive a limited distance without air in the tyre. The tyre might be wrecked after driving a considerable distance, but at least you can get to a safe place to deal with changing the wheel. 
• as the Hutchinson run-flats also function as bead-locks, they reduce the opportunity for the tyres to spin on the rim when the tyre is deflated for soft surfaces.
• As the tyre cannot fully collapse, the tyre is less at risk of being damaged by driving on it (hopefully at a slow speed sensible speed for a short distance).

The main down side as I see it, is the extra weight. Be aware that these wheels are almost solid rubber and difficult for the average person to roll the spare around due to the weight (even on a concrete surface). 

For the Hutchinson military run-flats, I have been advised of the following by the manufacturers: 

• Heat Retarding Lube is absolutely needed inside the tyre if you expect to run them flat for an extended period.
• If the lube leaks out or dries out or you replace the tyre, the lube needs to be replaced or the tyre can catch on fire if running an extended distance with no air.
• My size tyre requires about 48 ounces of lube.
• The lube is applied as a paste to the inner liner of the tyre under the belts on the crown. Unfortunately it cannot be inserted through the air valve.

Note: a special replacement 'O' ring is used to seal the two piece alloy rim. The proper Hutchinson version of the 'O' ring  is made of fancy materials so as to last in extreme temperature conditions. I am not sure if an 'O' ring can be re-used again, but if its in good nick I suppose its at the owners risk. Sounds like its a good idea to carry a few on trips. Hutchinson military rims, parts, repairs etc (including 'O' rings and lube) can be purchased from local company in Australia, Marathon Tyres. I am advised by Marathon Tyres that their:

• 'O' ring part number to suit this rim is Part Number: 50015
• heat retarding lube to suit this rim/wheel/run-flat combination, is Part Number: 500280
• Check the part number for your wheels as it may be different to mine (because I selected and imported my own wheels).

Assembly Bolts: Caution: When the assembly of (peripheral) 24 nuts are undone, the run-flat apparently tends to want to expand out suddenly and pop the face plate out. This can be a safety issue. When re-assembling the wheel, the donut run-flat needs compressing in order to re-fit the face plate.  Some owners (I am told)  fit longer bolts at every second hole as standard, as the odd longer bolts allow some nuts to be screwed on first and to compress the front plate down enough so that the rest of the nuts can be fitted. If you do need to change a tyre on a wheel fitted with a run-flat and you don't have these odd longer bolts, you will need to take the wheel to a place which has a large press, of a type suited to changing these tyres. Be aware that most truck tyre outlets apparently do not have the presses, though the ones that fit solid tyres to trucks (such as garbage trucks) may. My concern with permanently fitting the longer bolts, is that they will be exposed to damage and a risk to the public. They might not be permitted in Australia if the vehicle is being used on public roads?

Caution: The removal (should you choose) of the Hutchinson run-flat insert if not done properly, can damage the tyre (or yourself). One method to remove it, is to partially compress with a ratchet strap, place the tyre under the fork of an engine removal stand and slowly pull it up and out. Another method is to start pulling it out and when part of it is out of the tyre under tension, cut it in half (risky). However the proper method is to compress the donut into a squashed oval shape using a ratchet strap and carefully remove it by hand (this is the theory, but apparently does not always work in practice).  There are web sites explaining how to properly remove a run-flat. The pictures below, shows an example of a run-flat (with bead-lock also). 

The guideline states: When fitting wheel nuts, use light oil on the threads (in other words, not grease , not anti-corrosion spray, not WD40, not anti-seize but only light oil) eg Singer sewing machine oil to ensure one is able to achieve the correct repeatable torque. The torque value I am using is 425Nm on the Hutchinson military alloy rim. I also fitted the latest plastic indicators andwhich prevent a nut unwinding. After the first 250km I checked the torques from first tightening (new rims) and there was no change.

First photo is of my tyre at 48 psi. Second photo (on the right) is tyre with zero psi. You can see from the second photo that it does not fully collapse. The tyre might even be sitting on the run-flat at 20psi?

Further info on my wheels and hubs

The new Hutchinson/Michelin (XZL 395/85R20) wheels (with runflats) I brought in, are for the MRAP (Mine Resistant Ambush Protected) vehicle. They are alloy two piece removable face rim. My version combination has outer component model W0-1137 B 20X10 with inner component model WI-1137 F. When fitted to my vehicle the overall measures as less than 2.5m from outside to outside (that's the limit here in Oz). They work out to be 50mm offset inside and 50mm offset outside, from previous wheels. Local companies are also bringing in these wheels (new and used), so its easy to pick up a set without importing your own. Note that military Hutchinsons come in various outer and inner component combinations, which can result in different offsets. There are different combination versions being imported and you should first check that you do not exceed the overall legal width of your vehicle here in Australia.

I use my IR hand held sensor to check the hubs, diffs, gear box, after every major stop on long hot runs. By this means, one should be able to pick up any excessive wear problems as soon as practical, especially if one logs ambient and equipment temperatures.

Pictures two and three below show what to expect on the front axles after removing a steel wheel. I have removed the drum protecting the calipers hydraulic piping in the third photo for inspection, ready for general a clean up, grease and repaint. The hubs were all disgusting. I strongly recommend checking the ex ADF vehicles hubs carefully. The protector drums are a hassle to remove but they can protect the brake lines from damage. Note that there are 6 grease nipples on each front hub.  Note that I used an epoxy enamel on the hubs, as its a bit harder than ordinary enamel paint.

New wheel studs are from Germany: FEBI Bilstein 07940. They are grade 10.9, are 85mm long, M22x1.5. They are sold in sets of 20.  You can also buy individual bolts on ebay (but an expensive way to go). 

Photo above shows the footprint at different pressures for the Michelin 395/85R20 XZL.

Tyre pressure adjustments

Some higher end vehicles have in-cab tyre pressure adjustment on the go i.e. you do not need to stop or get out of the cab to increase or decrease the pressure of all the running tyres. There are two basic versions available:

• The version (often a retro-fit) which has exposed tubes on the outside of the vehicle can be easily ripped off on the first bush you pass and thus deflate the tyre,
• The integrated design where the air supply is connected through the centre of the hub, and has no external tubes exposed at the wheels.

Either way, both types of system apparently suffer the disadvantage of air leaks. From my analysis, the best value for money compromise is to permanently run air sockets up to each wheel location. You have to stop, get out, connect a short hose from each socket to each tyre.  Another option is to adjust the front pair separate from the rear pair. You can fit the control valve(s) in the cab and monitor the pressure, or if you prefer, do it from outside by hand, the old fashioned way. By this means, all tyres are adjusted at the same time to the same value. Its not as fancy as some systems because you have to stop and get out of the cab, but its going to be much less prone to leakage problems. UNIDAN have a RTIS kit for fast inflation and deflation if you don't want to make your own.

Spare Wheel(s) storage

I have observed some examples where people have fixed their wheel support brackets direct to flimsy parts of the living module structure usually not designed for it. It is likely best to fix the wheel directly to the chassis, tray or barge board where possible. Placing your spare wheel in front of the grill is not a good idea for obvious reasons (illegal if it blocks the foreword drivers view by any amount and could cause engine overheating?). Placing a large wheel above the cab can be even more risky unless the support arrangement is robust enough to allow for emergency stops or vehicle crashes. Whilst the 435 series cab is apparently strong enough to support a spare wheel under static conditions, you don't want your wheel ripping loose and becoming a missile (taking your roof rack with it and twisting the cab) under forward collision conditions possibly exasperating what might have otherwise been a minor impact scenario.  I was originally planning to place a spare wheel above the cab, but as they are so large and heavy, one will need a small crane such as the Splitz-lift. Its also likely to  be illegal here to put such a heavy weight on the cab roof rack unless the engineer has signed off that the arrangement is acceptable in a crash situation. 

Seats

I purchased a pair of new Sears 'Comfort Seats' made for CAT off-road trucks. They are of a very solid construction (overkill in fact). They have breathable fabric reputedly designed for Australia's harsh outback conditions. There are many good standard pneumatic truck seats available, I just happened to come across these, and I like heavy engineering. Try 'Mog Central' and 'Unidan' for some cheaper lightweight seats.

If you are replacing the existing ADF seats with a modern style, you will need much stronger seat support boxes. The original bench type seats, seat support boxs and frames are surprisingly flimsy (almost a joke in terms of robustness). My new seat support box's have been made to my design from thicker steel, fully welded (not pop riveted) and extra bolts to the floor pan with large steel washers underneath.  Something to watch for, is your final seated height. It's all too easy in these vehicles for your head to be hitting the roof or your knees touching the steering wheel if you install a seat which is too tall. My seats have a large dampening adjustment range (i.e. they can go up and down a lot more than average to accommodate big bumps in the road). But the down side is that they would not suit some people with meaty buttocks, they only just suit myself (being stick thin) and my head still touches the roof. Also, if the standard steering wheel diameter too large and touches the legs, there are extension bosses available to move the wheel higher up on the shaft. I fitted an approximately 4" high extension boss to suit a Freightliner 18"steering wheel.

The driver side floor pan is flat, but the passenger side needs shaping to the profile of the arched floor (fifth photo). I had both boxes made square and then cut out the passenger side to match the curved floor profile and then took it back to the local sheet metal shop for full welding.

Third photo is where I drilled the holes in the seat adapter boxes. I found that a magnetic drill is useful on this vehicle. It uses rotabroach bits; expensive, but worth every penny, as it can be very dangerous to try and drill large holes otherwise. Don't try using the drill without using the magnet. I found out that the drill bits shatter easily if the drill moves (and at about $50 to $100 per drill bit, not cheap).

Fourth photo shows fitment check for controls etc. Important also that you can adjust the seat and that your knees don't foul the steering wheel when using the clutch and brake.  

Fuel System

Tanks:

Fuel tank support brackets (along with matching 50mm wide insulation rubber strips to suit) are from Hilton Industries in Victoria.

It is not permitted to drill or weld the chassis (unless you know what you are doing). Its hardened steel anyway, so difficult to drill. I used 12mm plate adaptor brackets to pick up existing bolt positions on the chassis.

Fuel tanks are mirror polished 316 stainless steel (200L each) as used on the Ford F650 (these are likely still available from Ford in the US as spare parts or direct from the tank manufacturer). I chased up the manufacturers tanks drawings using the tanks serial numbers for my automotive engineer to scrutinise. Unlike some fuel tanks, these have a low vertical height so as not to hang down too low and be wiped out on rocks etc quite so easily. They have the required 3 connections (vent, fuel OUT and fuel IN), as well as side and bottom drain connections.

Fuel level senders are 0-180/190 Ohm marine stainless steel.  The pick-up is about 25mm from the bottom. Both tanks floats are wired to the existing fuel gauge, and I use a changeover switch to display either tank.   

Fuel Selection panel and Water Filter :

I installed a fuel selector panel to manually select fuel from either tank.  I kept it simple and fitted two marine grade 3 way manual operated brass diverter valves. One is for fuel OUT the other is for fuel IN (return). I need to make sure both valves are turned towards the same direction when operating them. 

There are many water filter products on the market all promising great things, so I decided I might as well go for a product from one of the big players. I fitted the MANN Preline 250/1 pre-filter with sensor and red warning light (kit). This unit condenses out water and brings up a warning light on the dash if too much water is detected and needs to be drained off. 

Note: the inlet and outlet ports of the MANN Preline 250/1 pre-filter can be swapped over for different mounting orientations.

The sensor and red light works such that: The red light comes on for a few minutes after the ignition is on, then if no water present, it turns off.

Telescopic Mast

Another useful item for security and or emergencies and improved communications at remote locations, is a telescopic mast to mount things like: antennas, flood lights, etc.  The better technology (but expensive) masts are usually slim, pneumatic and made from aluminium, and thus lighter. You can get cheaper models but they are often much thicker and much heavier for the same height. There are also electric masts which use a cable inside the mast to extend them. These can be prone to mechanical problems.

 They are available from small, to humongous in size (some about 14" in diameter). You can save money by buying a second hand mast. I managed to find a used military pneumatic Hilomast (11 meters) in the UK. It can lift 18kg of equipment (when new). I pulled it down, cleaned it and lubricated. I discovered that light oil is not suitable for the mast, as it drains out. Need to use lithium grease, so it stays in place. See photo of fully extended test where I fixed it to the side of the temporary workshop for testing. 

Wind pressure, lightning strike and forgetting to lower the mast are SIGNIFICANT risks. If lightning hits directly, all bets are off, and you may end up with a very expensive melted mess. WARNING: An extended mast is a lightning attractor and its probably prudent to lower it well before storm activity mind you, the act of lowering it could also get you killed!   I will likely fit an equipotential earth cable for use when the mast is raised as 'touch' potential can be lethal if you happen to be accessing the vehicle at the time lightning is around.  Interlocking with engine start is recommended to prevent accidentally driving off with the mast extended. Most mast suppliers have options to fit a magnetic sensor switch to the base of the mast to detect when fully descended. Alternatively an  industrial micro-switch can be used to carry out the detection in lieu (cheaper).

A mast is useful for area lighting and to place antennas when needed in an emergency. Good for flying the flag also.

   Pictures below show:

• the fitment of the mast on the headboard , and
• example of Curly Cord vs Cord spiraled around a mast on another vehicle

Frontal Protrusions/Projections

There are strict rules about sharp edges. No sharp edges can be presented on the front of a vehicle. I seem to recall that the minimum radius in Australia, under the latest ADR design rule, is 2.5mm radius. 

Brush Deflection Cage

If you are planning to go off the tar (and that's what the vehicles are meant to be used for) where tree branches etc might be an issue, you should consider a steel cage around and over your vehicle. As you have likely invested a small fortune in your home away from home, the last thing you need is to wipe it out by a low hanging branch that the council forgot to trim from the side of the road. Also most of the bush tracks to far away places of interest are likely to have been worn through by standard sized 4x4s. They have cleared the tracks from debris to suit their vehicles and usually not for trucks. You should consider that you might be needing to do a lot of sawing etc to clear a path. Ideally, a deflection cage needs to start at the front of the vehicle and gently curve up to the maximum height so that on impacting an object such as a small tree branch, the object hopefully gracefully slides up and over the vehicle, or the vehicle deflects down and under it. Perhaps better to be jammed under a bridge than wiping off the top of your vehicle? If the cage frame is to start at the front of the vehicle, it must not obstruct the drivers forward view. The rules around this issue seem very vague from my enquiries and perhaps not fully understood by police or even some transport authorities? One officer told me that he uses the 50mm rule, i.e. if the structure in front of the windscreen is wider than 50mm its non compliant? I have not been able to find any rules pertaining to the maximum view width obstruction to date. 

Bull Bar

Perhaps another decision is whether a bull bar is needed and if it needs to be frangible or not. 'Frangible' implies that part of the forward structure will collapse and absorb part of the impact. Non frangible implies a super rigid arrangement with the hope that small objects like cows and small cars will simply bounce off without doing too much damage? The down side is that serious structural damage to the chassis can occur with non frangible arrangements, as all the force is transmitted to the chassis. In any case its important that bull bars (frontal protrusions) are designed with rounded surfaces and no sharp projections which could cut or injure a pedestrian on impact. Both a structural engineer and an automotive engineer might be needed here for a frangible design, and each section may need to be designed to be bolt replaceable if they get bent (why replace a whole bull bar if only one side gets bent). I am keeping my arrangement essentially stock, with just one horizontal tube bar (clamped not welded) added to provide some underside protection.   

Frontal Projections Compliance Assessment

An ex ADF model U1700 Unimog is a universal all-terrain vehicle.  The vehicle includes a ‘thing’. A 'thing' is the technical term that the Australian vehicle design standards refer to, and in this case it is the pair of frontal cast  steel protrusions which for many of the ex ADF vehicles, forms a standard essential part of the vehicle.  The 'thing' in this case, is centrally located on the front of the vehicle.  In my vehicle factory configuration, it consists of a PTO winch head (Werner & Co winch) with adjacent cast steel structures often referred to, as 'elephant ears'. This forward winch consists of a gearbox on the rear of the engine, a drive shaft to the front of the vehicle and a (cable drum) head. The vehicle original compliance plate includes the 'thing'.

The standard winch head:-

• is designed with large radius softly curved smooth cast surfaces in order to not present any sharp surfaces, and
• protrudes past the front bumper,
• is close flanked each side with protective cast steel protrusions (structures). 

The two cast steel protrusions:-   

• are an integral extension of the vehicles chassis (the forward-most tips however, can be cut off in some circumstances),
• provide some mechanical protection to the winch head in the event of a frontal or side impact,       
• form part of, and are the support mount for the vehicles bumper bars, 
• are the support and mounting for the standard integrated winch,      
• are the frontal vehicle lifting points during maintenance or repair,        
• were used by the ADF for lifting the vehicle (by crane or helicopter) when no underside lift capability was available,
• are the primary point of cable attachment for vehicle recovery purposes, and 
• are the forward tie down points when transporting the vehicle on a low loader or a ship/ferry

....... the whole configuration/arrangement being fully in full compliance with the ADR’s applicable to pre 1st July 1989 builds. 

The Australian ADF UL1700L version typically uses two cast steel frontal projections as described in the previous section and which were designed for use in vehicle recovery and other tasks typically required in an all-terrain vehicle when used in the often harsh Australian bush environment i.e. lifting and dragging, as well as mechanical protection for the factory winch, where fitted. The two frontal protrusions are part of the chassis and also the mount for the standard winch, and when a winch is installed between them the whole arrangement presents a compliant broad frontal surface, in keeping with the aim of the latest ADR's.

Note: Second Edition ADRs are the applicable pre 1989 vehicle build design requirements and are silent in respect of front of vehicle protrusions.  It was not until 1989 that the Third Edition ADR’s came into being and made provision for vehicle protrusion rules.  The pre 1989 vehicle whether fitted with a winch head (or not) and or its associated ‘structures will be fully compliant with the ADRs applicable at the time of the vehicle build.

However, in circa 2012 the National Heavy Vehicle Law (NHVL) was enacted and this includes requirements additional to the ADR’s. In particular, it includes a rule regarding frontal projections. The new rule states “A thing fitted to a heavy vehicle must be designed, built and fitted to the vehicle in a way that minimises the likelihood of injury to a person making contact with the vehicle”. (Source: Heavy Vehicle (Vehicle Standards) National Regulation: Schedule 2, Other vehicle standards applying to single heavy vehicles Part 2 General safety requirements 7 Protrusions). This rule is subjective and has no definition. Note: If the intent is to comply with latest Third Edition ADRs, then some modifications will be required to the 'thing', from when it came out the factory. Typically a rounded pipe design bull bar is incorporated into the two projections to make it compliant to current rules.

It is sometimes the view by some learned folk, that these two frontal projections are not fully compliant with the latest 3rd Edition ADR (Australian Design Rules) however,  the current Third Edition ADR’s are not applicable to the pre 1998 vehicles in regard to frontal protrusions/projections and the NHVL does not require pre 1989 build heavy vehicles to comply with the current Australian Design Rules (ADRs) in regard to frontal protrusions/projections. However, some states (eg: NT) have enacted vehicle specific rules in regard to this standard factory fitted recovery/protective equipment requiring the two castings to be removed on public roads.

A compliance assessment report has been compiled by this writer (click on red link). The assessment report may or may not, stand up in a court of law. It is this writers view that the vehicles do essentially comply to the 3rd Edition ADR's because the projections are below the floor line (see Requirement 5.1, copied and pasted below). In any case, the frontal projections also comply with the 'sharp edges' requirements (using the 100mm rolling sphere) in all respects except the winch securing pins, the simple fix being a soft cover tube.

In simple language, the key take-away from the latest (3rd Edition) ADR's state that anything below a vehicles floor line does not need to comply to rules for frontal projections. But should insistence by learned peoples in a state transport authority require removal or compliance with latest design rules, such compliance could be easily achieved by (for example) incorporating the two projections into a compliant bull bar so that a wide relatively homogeneous curved surface is presented. 

Third Edition ADR (Source: Vehicle Standard (Australian Design Rule 92/00 – External Projections) 2018 General Specifications (requirements) section 5, in so far as it might be applied to a pre 1989 vehicle are listed below, together with a compliance statement in regard to the pre 1989 ex ADF U1700 Unimog:

Requirement: 5.1. The provisions of this Regulation shall not apply to those parts of the external surface which, with the vehicle in the laden condition, with all doors, windows and access lids etc., in the closed position, are either:

5.1.1.               At a height of more than 2 metres, or

5.1.2.               Below the floor line, or

5.1.3.               So located that, in their static condition as well as when in operation, they (i.e. any sharp edges less than 2.5mm radius) cannot be contacted by a (rolling) sphere 100 mm in diameter.

In essence, as I understand the situation: The zone below the cabin floor level and above 2m does not need to comply with Requirement: 5.1. in regard sharp projections. Does this help us much? perhaps.

Living Modules

Comforts

Pop top units may help with vehicle aerodynamics (having a lower profile), possibly saving a small amount of fuel and allowing you to get under some of the minor overpasses. 

The split type clamshell cabins (where the top shell sits over the bottom shell) often use pneumatic rams or cable winches to lift it up. These provide better  security but I am not sure how reliable they are in moving up and down, or for sealing to keep the bull dust out. In any case, I have rarely seen them outside the US web sites. Check out Bill Caids site for information on one such module. 

Living module Options

 I ended up purchasing a new 2020 model slide-on (aluminium composite panel with aluminium frame) camper advertised as made for military vehicles. The body is the right size for the truck tray at 4m x 2.2m.  I can just stand up in it without having to put the pop top roof up. 

In order to secure the camper to the tray of the truck, I had a subframe made by Beauchamp Metals.  Note: If you want to go for registration as a 'motorhome' the camper has to be 'permanently' fixed down (permanent structure) with tools required to remove it. The NHVR definition of  'permanently' fixed down is a bit vague. This can work for you or against you. Basically, if you need tools to remove it such that its a workshop job, then its permanent. If you can do it easily at a camp site, its not. 

Jacks: I have 1m extension legs (stored under the truck) for the standard jacks, in order to get the overall 1.8m height clearance required to remove the camper at home. The electricjacks are located on the rear wall of the living module.

Tray decking:  I completely removed the original timber ply as its not serving any useful purpose and had some rot in spots. I treated the metal frame for some minor surface rust before installing  lightweight foamed fiberglass sheeting (Thermo-Lite).  Incredibly light and strong. Note it must be painted if exposed to the sun. 

Spare Wheel Storage & Crane: I ended up storing the spare wheel (1.2m diameter and 400mm thick) on the tray under the void of the camper with the Spitz aluminium crane.

Safety Systems

Safety camera systems

I fitted a professional fleet management system. It includes:

• a forward view on both sides for side clearances,
• a top forward view to check height when passing under low bridges etc,
• a rear downward looking view and 
• a rearward view.

Emergency Strobe

Orange/amber strobe warning lights can be a useful safety item when coming across an accident or having broken down yourself. They are typically used as a light bar on the roof of emergency trucks including tow vehicles. 

Note: Its illegal to use any colour other than orange here in Australia and we are not permitted to drive with them running. In fact only certain vehicles can operate them at all. Basically, it is illegal for a private individual to  turn one on whilst in the public domain (roads etc). However, the NSW Vehicle Standards Information sheet publication 10.366 dated 24 Nov 2010 advises: ' The light does not have to be removed when the vehicle operates in non-hazardous situations but it must not flash.'   it also states that 'Examples of vehicles which can be fitted ... are: Volunteer vehicles not accredited by the State Rescue Board.'  

If you do intend to fit one, best to have an indicator switch in the cab, so you don't miss leaving them on whilst driving. Check your local state laws about their usage. I fitted a removable rotating beacon on the roof.

Condition Monitoring

Even with a militarized commercial engine and transmission, its still a good idea to monitor the temperature of various critical systems. There are many add-on engine management systems available on the market. They seem either cheap and dodgy or laboratory quality and very expensive (overkill). 

Temperature Transducers

The higher temperature transducers are either thermocouple or RTD type. As we do not need precise accuracy (a couple of degrees either way should be fine), a thermocouple is ok. The most common and cost effective thermocouple is the K type as it covers a very wide range typically -300 to 1250C (hence it will do everything). Note that if you are extending the cable (as it forms part of the thermocouple), you must use compensating lead. To use copper can cause inaccuracies. Even the jointing of the wires would normally be done using compensating terminals, though I have found that its not needed for our accuracies.

Lower temperatures are often done with negative coefficient thermistors (oil, water etc).

I consider the following functions important to check:

• engine oil temperature,
• gearbox oil temperature,
• differentials oil temperatures (manually using thermal gun),
• hubs oil temperatures (manually using thermal gun is ok for me),
• exhaust gas temperature,
• engine water jacket temperature,
• engine oil pressure,
• air inlet manifold pressure,
• Tyres pressure,
• Tyres temperature.

Most engines (in general) are de-tuned by the vehicle manufacturer to make them semi idiot proof. If for example you bypass the turbo safety limits, you should fit EGT and turbo  pressure monitoring to help ensure that you don't exceed the manufacturers general design limits.

Temperature monitoring of hubs and differentials could help to detect a failing bearing before catastrophic failure. However, presently I just use my hand or the IR meter to compare temperatures. If they are all the same, then probably no issues (expect the front hubs to be fractionally warmer than the rear, as the front do most of the braking effort). Investing in a contactless infrared meter is a sensible way to go, as by this means, you can check all of the drive train components at regular cycles and write the values down in a log book. If you see one going up over time, it might mean a problem that needs looking at? Catastrophic failure of a bearing is not something you want to happen, anywhere, especially with a large non standard vehicle, so I cannot strongly recommend enough, the importance of regularly checking non monitored drive train component temperatures after every long run.  

Madman EMS-2

I installed the MadMan EMS-2 monitor. To date, I have connected the following parameters (because they were easy):

• Engine oil
• Gearbox oil
• Coolant level

I have fitted a standard 1/8 NPT VDO temperature sender to the gearbox via the forward drain hole using an adapter. The EMS-2 has a standard calibration curve for a standard VDO sender. Best to get the same model sender that MadMan nominate, otherwise you will have to program the temperature vs Resistance curve for another type of sensor.

Engine oil access was a bit trickier. I accessed engine oil temperature from one of the oil filters M10x1mm drain plug (because its easy access). I used the VW coolant sensor (LT 027919501) as its the only short barrel M10x1mm thermistor sensor I could find easily available (used in dozens of different vehicles).  The EMS-2 needs to be programmed for this sensor curve.  I programmed in 6 points across the curve (should be enough). 

Note: Its important to run a negative wire to each of the sensors, as the earth returns might not be solid. The gear box for example might not be sufficiently well earthed and this may cause intermittent results. The below photo shows a method of earthing the oil temperature sensor. Its a ring lug and a few copper washers to ensure that the earth is available for the sensor return path. One wire for the sensor and one wire for the earth.

Dash Lights

I replaced the original incandescent bulbs in my dash with LED versions (better longevity, less current, brighter, pure colour spectrum).  As they are bright at night, I have removed relay 17, and hardwired a new relay to switch in a custom resistor (about 10k Ohm from memory) to dim the LEDs appropriately at night. 

Portals Temperature

When seals wear, its possible for portal oil to be sucked past seals and into the diff, thus starving the portals of oil. 

There are various ways to monitor their temperatures.  At the moment, I just use the thermal IR gun and walk around and touch the hubs after a drive to compare temperatures. 

Oil temperature - General

Oils need to be maintained within a strict temperature range. The engine combustion process produces water and the intake air of course has water vapor in it. This finds its way past the piston rings into the crank case oil and causes corrosion of bearings etc. In order to avoid the problem of water (condensation) oil needs to be above 100C (to drive off the water) but not too hot so as to break down early. Accordingly, the ideal range is between 110C and 126C. Its a very tight range to try and manage.  In fact the only real control over oil temperatures (unless you go high tech) is your driving manner and simple monitoring systems which will enable you to maximise the longevity of your investment by driving appropriately. 

Door Latches

First off, I fitted a Heavy Duty Rhino wireless 24v central locking (via motors) and alarm/immobiliser. The Rhino system has the usual rolling code technology etc.

If it is required to latch/unlatch the door latches via central locking motors, a rod connection point needs to be welded to each of the existing mechanisms in the doors. I found that my door latches are too stiff for being motor latched/unlatched despite fitting heavy duty mechanisms. I have disconnected the connection rods. 

Tyre Monitoring

A solid state digital tyre monitoring system is a must in my view. In-cab wireless centralised tyre pressure/temp monitoring systems are now cheap and easy to install and two options are available: sensor is inside the tyre or the sensor is on the outside of the tyre (screwed onto tyre valve). 

They can be an invaluable product for warning of tyre pressure problems and over temperatures as its highly unlikely that you will be able to obtain a replacement tyre of the right match and quality off the shelf, and especially in the middle of nowhere. Its worth also monitoring the spare wheel(s) to ensure they have not gone down over time. 

Here's my assessment:

   1) Inside tyre sensors

Advantages:

• Protected from damage.
• Normal flow rate when adjusting pressures.

Disadvantages:

Sealed (battery normally not replaceable) and item need to be replaced when the sealed battery expires. This means removing the tyre (very big job in my case). However, if this is every 5 years, it might be a viable option?. However, as my wheels have military run-flat inserts, this limits me to the external types of sensors, as detailed further below. Probably not suited to wheels with bead-lock inserts either.

   2) External to tyre sensors

In-line version and end of cap version.

Advantages: Cheaper than inside sensors. Battery usually replaceable and easily replaceable, but generally needs to be replaced every year. In-line version does not need to be removed to adjust air. 

Disadvantages: If you have rubber valve stems you should probably change them to metal, as rubber can allow the sensor to flop around potentially causing damage to the sensor and a leak. Capped version needs to be unscrewed to adjust air pressure, are assigned to a specific tyre and can be mixed up. It may take the monitor a while to display the pressure after the sensor has been disturbed. Someone can steal it easily or it falls off (and with the in-line version, your tyre goes flat) In-line version is exposed compared to the capped version (as it sticks out a lot more), and can restrict air flow. 

Other options to consider:

• absolute pressure measurement (safer and easier to use), or
• calibrate yourself (risky and a hassle),
• real time monitoring (picks up problems asap),
• low battery alarm. Systems that don't monitor their own battery voltage wait until they are no longer receiving input from a tyre sensor for a period of time before warning of a problem. I have read of one product that takes 45 minutes. This is a worry as you might have no monitoring for that period.

Future needs. Do you want to fit your spare wheel(s) with sensors and also allow for anything being towed? If intermittent towing, perhaps best to carry some spare external sensors so they can be quickly screwed to any as-hoc trailer or caravan you decide to tow.  A commercial system for large trucks is likely to be the best as should be designed to provide a good signal strength and they often have options to add additional wheel sensors. 

I ended up buying the B-Qtech 6 wheel sensor set (from Amazon US). I fitted the four wheels, one on the spare wheel (and one is a spare). I checked the temperatures displayed for each tyre with my infrared gun and they were within 0.5C, that will do me. Pressures are sufficiently accurate for me also. For a while it was in permanent alarm mode and I could not figure it out. I thought it was defective, but I eventually condescended to reading the (poor) instructions and eventually figured out that one needs to enter the actual tyre pressure (as displayed) for each tyre in the alarm settings. Once I matched them up, the alarm stopped. Seems to be working ok. It will be a hassle to have to re adjust the alarm setting whenever I change tyre pressures, buts that's life. I also purchased a set of de-flator screw on valves. I have pre-set them to 25psi for the moment. That all work ok, and save time by not having to hold in the valve by hand.

Fast-flow/fill valves could also be  useful also, especially if you need to fill a flat tyre in order to re-seat it or if you are often adjusting tyre pressures (but you would need a very big reservoir added, to be able to take advantage of these valves). 

Paint Schemes

The ex ADF platforms here in Oz come with the traditional camouflage paint scheme to suit the Australian bush environment. There are lots of web sites providing information on colour codes for those who want to match up correctly. The paints used (at least in Australia) are made to special formulas in order to reflect Infra Red light. The main paint supplier is Protec. They supply the 601 series Camouflage Enamel to APAS-0165/1 . Protec advise that their 342 series is the standard domestic automotive formula and there are no restrictions on buying it. However, if you want the proper military paint with all the high quality materials, its the 601 series, and almost impossible to purchase without a military purchase order. On the down side, in a breakdown scenario in the middle of nowhere, its probably not a good idea to have a vehicle which is difficult for the rescue services to find using infrared. 

The following are the Protec domestic codes (not infrared light reflecting):

• 342-5726 - Camouflage light Tan
• 342-5265 - Camouflage tan (brown in actuality)
• 342-1166 - Camouflage Green (likely the origional Olive Drab?)
• 342-7165 - Camouflage Black.
• 342-5239 - Camouflage Pilbara Brown (more like a dark red). Not used on Unimogs to my knowledge.

Dark colours can cause heat problems. The outside of a dark vehicle absorbs sun heat easily and re-radiates it back into the vehicle compartment's. 

I have decided on plain acrylated enamel . Its not the most robust paint (quite soft unfortunately), but it makes life easier to use, as I am doing my own painting. I've gone for the common toyota white 058. Chassis will remain olive drab. 

Warning: the original polyurethane paints used by the military can be dangerous to your health (vapours including sanding dust, certainly made me feel sick). Make sure you are wearing PPE respiratory protection when working with this type of paint (or any paint for that matter). I see no point in sanding off the existing paint where its well adhered. Its a very hard paint, and a good base for other paints. Just make sure you give it a light sand and degrease before you paint over it.

Steering Wheel

With an air ride seat fitted, there is little room left under the steering wheel for the legs and the wheel may become too far away for comfort.  I purchased a Freightliner 18" wheel and a 5 bolt alloy Freightliner truck extension hub to suit from the USA. With this combination, I can reach the wheel comfortably and my knees do not touch. Note these parts must be a heavy truck rated/designed and not the flimsy stuff used on sports cars etc (even if they look similar). Be aware  that in the event of steering pump failure, it requires additional effort to turn at low speeds and a car style steering wheel will likely just crumple in your hands (not something you want in an emergency, plus you may not be able to source a replacement for a while). The wheel shaft has 36 splines at 24.5mm diameter. 

Filters

• Main Air - MANN  C27 585/3
• Oil cartridges (two) - MANN 932/4x
• Fuel (two) - MANN BFU 700x
• Steering - MANN H 601/6
• Cab air - MANN CU1836. 

Oil Capacities & Drain/FillPoints

Two most powerful brands are: 'Dimple' and 'Gold Plug'. Here's what I have measured and fitted to date:

• Portals measure as M18 x 1.5. Gold Plug AP-05.
• Engine sump measures as M26 x 1.5 and gearbox measures as M24 x 1.5. 
• Differentials measured as 24mm x 1.5 tapered plug with 14mm female hex socket. Dimple M24 x 1.5 tapered see below (blue product).
• Main gearbox case has 3 plugs (same plug as differentials). Two are drains and the highest one is the fill. I measured as 24mm x 1.5 tapered plug with 14mm female hex socket. Dimple M24 x 1.5 tapered see below (blue product).
• Clutch/PTO case has a fill and two drains. Note: There is also an inspection plug below the clutch bell housing which should be checked every so often for seal leakage issues.

 Don't take my word on the sizes, check them yourself.

GL-5 is apparently not suited for the synchros, so I have been advised to use GL-4. I use Castol Syntrans 75W-85 which complies with MB235.4.

Portal Hubs:

Your front hub should look like this, tidy and reasonably clean before you do any work. It is recommended to unscrew the 'fill' plug at regular intervals and especially if one of the hubs is running hotter for no obvious reason eg: sun shining on the wheel. Check the oil levels when the vehicle is on a level surface.  I mention this because there have been reports of internal seals being worn and portal oil being sucked out into the diff/axle cavity.

Before undoing, wipe around the plug to remove all dust (not done in this photo of a dirty hub, as I'm not undoing anything).  Also good to keep a set of spare copper washers on-board.

Note: F is the 'fill' plug and 'D' s the drain plug for the portals. I have retro-fitted stainless magnetic drain plugs all around. These are about A$75 each (the good ones), and work well. They are so strong its a bit of a fiddle to get them to sit in the centre of the hole to start the thread. Always start off the thread by hand. If you cannot start by hand, there is likely something wrong. Never force it.

Brake Bleeding

In the picture below, the front brake bleed screw is circled. It normally has a rubber cap on it. In some cases (like this) the brake line is in front of the bleed screw obstructing direct access to the screw using a deep socket or box spanner. In this example, the rim protection ring/drum will need to be unbolted and pushed back out of the way in order to get access using a spanner. Unless you have the proper tube bending tool, perhaps not worth risking cracking the line by trying to bend it out of the way.

Pneumatic System - General

One of the important things to do with an older vehicle like this without an air dryer, is to check the air system for contamination. The vehicle relies on a clean reliable air supply, so the tanks, valves and tubing etc need to be clean. There are 3 reservoirs (2 high pressure, and one low pressure) that needed cleaning out. Tanks may need to be de-scaled and ideally sealed against rust (I used Red-kote for the tanks as it binds with rust but does not like sticking to shiny smooth surfaces). 

I have added another smallerauxiliary air tank under the cabin for: air horns, air ride seats, pneumatic mast etc along with manifolds, regulators and control valves.

If your vehicle is like mine, a significant number of the air line olives will be frozen (corroded) in place and will not be easily separated. I had to be patient and use penetrating oil. When refitting the olives, I'm using Loctite aluminium based anti galling thread compound on the olives. Be advised that its easy to damage sealing surfaces and some replacement parts are next to impossible to purchase. Most of the air fittings on my vehicle are Voss brand.

Compressor Output

The piston compressor on the ADF vehicles is belt driven. Its awkward to change the belt.  Unlike a rotary compressor typically used for cabin air conditioning which has a clutch in it so that its not being driven all the time, the vehicles piston compressor is being driven all the time the engine runs. There is an optional direct drive piston compressor which (in theory) can be fitted to the side of the engine by removing a cover plate, but I don't believe that there is room for it on these vehicles. The output from the piston compressor is quite high (about 1.8MPa). The vehicles high pressure system needs to build up to about 1.2MPa before the park brake actuators (connected to the low pressure system) will release.  

Regulated Air

The air from the compressor is regulated down for general use on the vehicle. There are dual reservoir tank systems. One system is regulated to about 700kPa and the other about 900kPa.

Braking System

Master Brake Actuator

The master brake cylinder is controlled by an air actuator (air over oil). The air actuator is controlled by pneumatic valves which are connected to the brake pedal. My air actuator is a Wabco part 421 517 082 0. The repair service kit seems to be part 421 517 001 2.

After pulling down the Wabco air actuator, it was in good nick, with no signs of corrosion. I only needed to clean, spray paint the slightly rusted mating surfaces, grease up with silicon based grease and fit a new 'O' ring before reassembling.

Pneumatics & Braking System

Park Brakes

Park brakes are only on the rear. One of mine was not working (jammed OFF). The parking brake actuator cylinder lever device on the hub is spring loaded, so watch out when the pivot pin is removed, as the lever will fly towards the wheel direction.  Be careful if disassembling an actuating cylinder, as there is a large and powerful spring inside. I used a hydraulic press for disassembly and re-assembly when re-furbishing them. 

Brakes - Pads

When setting up (refer to manual G 603 page 127) there are two adjustor screws. See the second and third photos below showing the hex key in the adjusters. The adjustment screws wind the pistons sufficiently inwards to get the old pads out. 

Note: The front have sensor wires to provide a warning light on the dash when the pad is worn down. This warning system is not fail-safe design, and not designed to warn of catastrophic failures. 

 Hydraulic Jack

The military standard jack which comes with the vehicle (drab olive green shown on the left below) is sticker rated at 10 tonnes, but built like you would expect a military piece of hardware, and very heavy. The photo shows an ordinary jack next to the military spec jack on the left. The manufacturer of these Unimog jacks is now called Andrew Engineering (Melbourne). They don't sell the seal kits any more but any good engineering company can refurbish the jack with standard parts.

Compressed Air Dryer/Filtration - Kit

There is no filtration or auto water removal system on these trucks. I guess the military wanted simplicity with less things to go wrong. After making enquires under freedom of information, I found that a bolt-on filter/dryer kit had been designed/purchased for the fleet, but not installed.  Apparently the ADF were having too many air system failures (the vehicles were becoming unreliable and maintenance costs were rising) simply because drivers were not very good at bothering to regularly flush the air tanks.  So they had a local company design and build a modern auto flush system in the form of an add-on kit.  The special ADF retro-fit Air Filtration/Dryer kit has been purpose designed for the U1700 (435 series). Quite a number of kits were supplied to the ADF for use, however, before they could fit them, it appears that the ADF may have gotten wind that the fleet was to be replaced and left them in storage.

The filter unit is a coalescing type, so unlike most (if not all) other types on the market who use replaceable cartridges, it does not need to have anything replaced when it fills up. It automatically flushes away the waste. This system saves against having to manually drain the tanks every day. I do recommend this kit as it has kept my air system sparkling clean from crap and water since I installed it. The kit comes essentially complete with everything including the solenoid cable and all the fittings to suit the 18mm high pressure line, in order to divert the air through the filter system via flexible braided hoses supplied in the kit. The photo shows two standard fittings used to break into the existing 18mm steel line. 

WARNING – COMPRESSED AIR MAY CAUSE SERIOUS INJURY OR DEATH AND ONLY PERSONS WITH THE APPROPRIATE COMPENTENCY SHOULD ATTEMPT TO CARRY OUT INSTALLATION OR MAINTENANCE WORK.      

The air filter/dryer system is installed between the air compressor and the braking system, i.e. on the output of the compressor. The equipment is intended to filter out a portion of water vapor, oil vapor, and other contaminants. This may help prevent freeze-up during the winter, corrosion of steel, the gumming up of equipment due to oil carryover from piston compressor and may extend the life of air valves/regulators and pneumatic cylinders on the truck. Most trucks use ordinary replaceable desiccant cartridges requiring regular changes of the cartridge, and according to the manufacturer this kit was designed in collaboration with the ADF engineers and the Australian company ‘General Pneumatics’ to be robust, automatic and needing minimum maintenance. The kit includes a wet tank, a Dumpmaster 500 (coalescing) filter, two electronic ‘non block’ auto drain shuttle valves and fittings to provide a total air system filtration, according to the manufacturer. The shuttle valves and the filter unit do need some regular minor maintenance, but I've had no issues since I installed mine years ago. So long as you continue to hear the pop-off of the air flush about every 6 minutes or so, then its set and forget.

Mode of Operation: The air from the compressor flows first into the wet tank where any slugs of water should collect at the base. The air then flows out of the wet tank into the coalescing filter unit where most remaining water vapour is removed and which should collect at the base of the filter. The significantly dryer and cleaner air then exits the filter unit and flows on to the main pressure regulator (dump valve). At approximately 6 to 10 minute intervals, the shuttle/ejector valves both pop open for a short time and dump a small amount of air to atmosphere carrying away any water that has been collected at the base of the wet tank and/or the filter unit. Note: The discharge of air makes a loud popping sound which can startle.

Servicing/Maintenance: Maintenance (ejector service kits) for the ejector shuttle valves, should be still available from General Pneumatics, now trading as GP Truck Products in Victoria;  https://gptruckproducts.com.au/ This writer understands that shuttle valve ejector service kit XD-102 is still available   (https://gptruckproducts.com.au/?s=xd-102&post_type=product).

Note: The 3rd tank (under the cab) is not fitted on some Unimogs. It is a tank for ancillary devices. This 3rd tank is optional and not necessary for the filtration kit to operate. In fact, it is in the way of the filtration kit, and the adaptor plate allows it to be moved further forward, in order to fit the new wet tank. The 3rd tank is also a convenient place to pick up a low pressure air source in order to operate the shuttle valves.

What's in the box:

Photos below, are examples from the maintenance manual showing the level of detail.

Cab Security

Its apparently illegal to leave a vehicle unlocked and unattended for more than a set time period or distance, in Australia. So I replaced the door handles with key locking versions. I purchased more modern square style lockable Febi door handles . I had a locksmith set both door handles to the same key.  The existing ignition switch (Neiman 0310 style) has a captive slotted key. I installed a new ignition key barrel from Mog Central.

Dash & Associated Electrics

I added a forward junction box made of stainless steel and nylon cable glands fitted to keep it water proof. Lower photo shows cable glands fitted before cabling installed. 

I have added 4 x new heavy circuits (with 13mm square, multi-strand flexible copper cables), with 20A Maxi fuses fuses located next to the batteries. Sub circuits are run off these, incorporating standard size automotive blade style fuses.

The drivers dash facia was slightly warped. The only way to make it new, was to pull it out and panel beat and repaint. See gallery photo below.

There are a row of warning indicator light plugs behind the facia, so mark all of them all before you disconnect them (best to take a photo of the order of the indicators before starting). 

Note: The circuit breakers in the cab dash screw down to a flimsy plastic base. These plastic support bases are fragile due to age. 

 Picture below, shows some of the electrics at the dash.

The MadMan engine monitor is shown just above the ignition switch. It has an in-built warning light with noise maker. It is used to accurately monitor engine and gearbox temperatures and water level. The Auber Turbo monitor (below photo) is shown above the headlight switch. It has a warning light with noise maker to the left of it. It is used to monitor turbo exhaust gas temperature and boost air pressure. 

Display Screens

This is the semi-final arrangement with the quad cameras screen lowest and the tablet (GPS maps) above it on an adjustable stalk. This arrangement ensures that I am not blocking my view of the road ahead, and the tablet is close for viewing.

Steering Issues

I was going to buy the MB genuine replacement steering pump high pressure hose assembly but balked at A$350. I took it to the local Pirtek shop and they replaced the rubber hose section for A$140 (and a much stronger hose). Below are photos of the original hose assembly and the repaired one. 

Note that there is a filter inside the steering oil reservoir. Its MANN part H601/6.