Unimog Camper under construction

#31
MB did use shock absorbers on the U1700 tray - my tray came with one, but I did not re-fit it. I want to first see how it performs before I spend the money, but I will weld on the brackets for shocks as it will be easier to do now then to retrofit later - brackets don't cost must. Sorry for the bad photo - not one of mine. It shows the OEM show on the end of one of the subframe tubes, mounted onto the chassis just in front of the transmission - the grey blue thing under the spare tyre is the shift cylinder. The brown brackets are the fuel tank brackets.

I think my subframe is very rigid and since it original had a shock absorber, so it must be strong enough. I don't think any more stress will get transferred to the camper box. I think the idea is to stop the rocking, just to dampen the movement but still allow it to move and flex - just not as fast.

I'm also looking at fitting shocks to the cab - MB supply them as an option as well.
 

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#32
That's very interesting, I didn't realize MB had shock absorbers installed on the subframe as stock components. It makes sense thinking about how the truck would react if you hit a big bump at high speed - in that case you don't necessarily want a really flexible frame, you want the truck suspension to take the hit. But at slow speed you want the frame to flex for traction and to reduce stresses.
 
#33
Quick up date:

I am replacing the gears in the portal axles with new high speed gear sets - this will enable me to drive at 100kph @ 2200rpm. After stripping the left hand portal, the bearings all looked fine so I had planned on just putting in the new gears and saving myself the $1600 or so for new bearings.

On stripping the right hand side I discovered that the bearings were very close to total failure - see the photos below.

TO cut a long story short, the mechanic who had worked on the truck previously, had fitted normal "Industrial" strength ball bearings - however, the load rating on them is about half of the "heavy duty" bearings that MB specify. The result was that the those bearings had worn out, and contaminated the large outer roller bearing resulting in them wearing as well. Checking the left hand side I found that they had replaced the bearings on that side with "normal" bearings as well - so I have decided to replace all the bearings.

I tried to get the "heavy duty" bearings form my local bearing places - and after much searching came up blank - they just could not get exaxtly the same specification bearings - they came close, but consulting a bearing book and reading all the number on the bearing, the closest they could come to is about 80% of what was required. In the end I got the bearings from a UK Unimog dealer in nice MB boxes at around the same price as the "normal" bearings from Australia - I also found out that MB have upgraded the ball bearing in the upper gear to a roller bearing - checking the bearing books again - the roller bearing has about 20% more capacity than the original bearing and more than 75% more capacity than standard industrial bearing.

In the end I all I have left from the original portals are the casings, the wear rings and the bolts - I have new gear sets, bearings and seals, so that should be good for another 100,000km or so :smiley_drive:
 

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#34
Hi Iain,

I'm from Hamburg in Germany and happenned to come across your article and thought you could be interested to see a few pictures of my Unimog camper 435.115 (1300L).

http://www.arkemander.com/mainsites/Unimog_web_gallery/index.html

I have new gear sets, bearings and seals, so that should be good for another 100,000km or so
Never ever (according to my experience) - depending on the axle load and maintenance most probably you will have to renew them after 45,000 to 60,000 km.
Have a careful look at the oil-drain plugs (the ones with the magnet, from the portal gearbox housing). If there is more than just powder then it would be an indication for an upcoming defect of the roller bearings. If it's detected in the very beginning you just have to change the roller bearing, otherwise the driven gear (the big one) as well.

Good luck,
Hilmar
 

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#35
Hi Iain,


Never ever (according to my experience) - depending on the axle load and maintenance most probably you will have to renew them after 45,000 to 60,000 km.
I hope that's not true for the U500
Mine has 64000km and so far no leaks or other symptoms. I only carry one set of bearings but lots of seals as spares. I have changed the portal oil twice, I always use Delvac Synthetic Gear Oil 75W90.
So far just a bit of fine dust.

Charlie
 
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#36
Thank Hilmar - I'll check them regularly. I plan to use only synthetic oil, and I'll have temperature sensors on them - so I can see if they run hot.

I will be checking the portal oil regularly - I have custom gears so don't want to damage them.
 
#37
Hi Charlie,

You are right, the U500 models

Model 405200 = U500 rear axle 747590 HU 5/2CS-9.0
Model 405201 = U500 rear axle 747590 HU 5/2CS-9.0 and 747592 HU 6/1CS-9.5
Model 405220 = U500 rear axle 747590 HU 5/2CS-9.0
Model 405221 = U500 rear axle 747590 HU 5/2CS-9.0 and 747592 HU 6/1CS-9.5

have axles with nominal axle load of 9.0 respectively 9.5 metric tons (the last digits give the nominal axle load).
The constructions of axle tubes and wheel hub drive are different compared to the U1200 and U1300 and U1500 models.

U500 models are used in Germany mainly for municipal services and not at all as off-road trucks.
Instead the U5000 models 437430, 437431, 437435, 437436, 437460, 437465, 437470 are used but they are hardly available and serviced outside the European Union.

Rear axles used in U1200 and U1300 and U1500 models:

Model 424122 = U1200 rear axle 747110 HU 2/13S-4.0
Model 424126 = U1250 rear axle 747112 HU 2/14S-4.0 and 747420 HU 3/1S-6.0 and 747421 HU 3/1S-6.0
Model 424127 = U1250L rear axle 747112 HU 2/14S-4.0 and 747420 HU 3/1S-6.0
Model 427101 = U1200 rear axle 747110 HU 2/13S-4.0 and 747115 HU 2/13CS-4.4 and 747118 HU 2/13CS-4.4
Model 427110 = U1250 rear axle 747112 HU 2/14S-4.0 and 747116 HU 2/15CS-4.4 and 747119 HU 2/15CS-4.4 and 747361 HU 2/18S-4.5
Model 427111 = U1250L rear axle 747112 HU 2/14S-4.0 and 747116 HU 2/15CS-4.4 and 747119 HU 2/15CS-4.4 and 747361 HU 2/18S-4.5

Model 435115 = U1300L rear axle 747111 HU 2/14S-4.0
Model 437110 = U1350L rear axle 747114 HU 2/12S-3.7 and 747121 HU 2/14CS-4.0
Model 437111 = U1550L rear axle 747114 HU 2/12S-3.7 and 747121 HU 2/14CS-4.0 and 747362 HU 2/19CS-4.5

The last three models are very common here in Germany because they are used a lot in the German army (Bundeswehr) and are available second hand for reasonable prices.

My Unimog originally was a 435115 = U1300L but I changed the wheel hub drives (the portal gearbox housing) from 747111 HU 2/14S-4.0 to 747362 HU 2/19CS-4.5.
Not only because of the nominal 500 kg higher axel load but mainly because of the bigger and stronger construction of the portal gearbox housing and the bigger oil reservoir (450 ml compared to 250 ml before).

Hilmar
 
#38
I'll check what mine are - but they all have approximately 450-500ml of oil in them when I filled them to just overflowing the fill port. My truck is fairly unique - it started life as a U1200 - chassis no. is a 424122xxx but them it was changed by MB Australia into a U1250 after it did not sell but it kept the same chassis number. According to the VIN number records, it was produced in Germany in 1982, but according to the compliance plate it was built in 1984 and sold as a flatbed truck. It was modified into a Road-Railer in 1985 for the New South Wales Railcorp - and I bought it in 2009.
 
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#40
Hi Hilmar - great website, thanks for the info. You have some great features built into you Mog.

Please can you tell me a bit more about you tire inflation system. From what I can tell, it seems you set the pressure and just connect up the air lines then wait? Is that correct?
 
#42
Hi Iain,

A bit of history: I bought the Unimog second hand in 1994 from the (French!) army here in Berlin. It was 6 years old (manufactured Sept 1988) with 26,000 km. Motor was and is 366A, original 136 HP/100 kW, 470 Nm; later modified 220 HP/162 kW, 670 Nm. Additionally I mounted a Split Transmission. Transmission ratio (split low) 23:9 * 27:13 = 5.30769, split high = 5.30769/0.82629 = 6,42352

The cabin/body only I had built according to my drawings from a company making refrigerated trucks, because I wanted a GRP-polyurethane isolated bodywork. The interior work I did myself. This took me a bit more than a year.

Since 1996 I started travelling in the African Sahara, that’s why I wanted the tire inflation system. The original system from Daimler-Benz was extremely expensive and nearly not possible to be upset subsequently. What I found was this:

http://www.ptg.info/Pages_E/03Products_Frame_engl.html -- tractors -- AIRBOX
http://www.ptg.info/Pics/10Info_Download/Film/Unimog.wmv
http://www.ptg.info/Pages_E/02Home_Frame_engl.html

It seems you set the pressure and just connect up the airlines then wait? Is that correct?
YES

Hilmar
 
#43
HI Hilmar - I had a look around my axles and portal - could not see any number on them of than these in the photos.

Where would I find the numbers your are referring to?

A friend borrowed a cab lifter for the day - and I have tilted the cab to be able of run new air lines, paint the underside and do a few things around the engine.
 

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#44
Hi Iain,

Where would I find the numbers you are referring to?
If original, there is an identification plate on the differential housing, showing the transmission ratios, the type and model of the axle and the individual axle number.

The wheel hub drive (the portal gearbox housing) is considered part of the axle and "normally" not interchangeable between axles of different series.
The housings, hubs, gearwheels etc. of the portal gearbox can be totally different between the different axle series.

If the identification plate is missing or meaningless because of individual modifications, the numbers can only be found from the records.
If the truck was serviced from an official Unimog shop and they updated the records in the EPC system you can even look it up there.

Last possibility: In the EPC you can search for individual part numbers and you even can search in which models these part numbers are used (a kind of reverse engineering).
If you search with the numbers of the two gearwheels from the hub drive it should be possible to find out for which axle types they were designed.

Front axle designation = 737
1xx, 2xx et cetera are the axle series designations
xx is the type of the axle within the specific series

737.1xx
737.2xx
737.3xx
737.4xx
737.5xx

Rear axle designation = 747
1xx, 2xx et cetera are the axle series designations
xx is the type of the axle within the specific series

747.1xx
747.2xx
747.3xx
747.4xx
747.5xx

After the specification of the axle the individual number of the axle follows.
For instance my front axle has the number 737.111 1I 009919
737.111 is the specification of the axle and
1I 009919 is my individual axle number.

The picture shows the portal gearbox housing from a 747.111 axle compared with a 747.364 housing.

Hilmar
 

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#45
Mine look like the 747.111 housing, yet they take 450-500ml of oil. The top gears are also different - I have the flat face upper gear as opposed to the spline type. The brakes supports look substantially different on the 747.364 as well - those look like the bigger brakes found on the U1700's we have over here
 

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