Unimog 406 and later Axle info.

by Sapper

After looking around for info on the 406 and later model axles I quickly discovered that there was little to be had at least on the internet and much of what you would find would not be of any real use nor could you trust it.  With the help of many other POR members I started to assemble the info gathered in these pages for an online source of information that everyone could access and trust.  I may come back and add info in at a later date but right now this should be the best online source for information put together on the internet for later model Unimog Axles.

First I would like to state that these pages are listing information directly from tech manuals which have been tediously transferred into html to be as accurate as possible for use.  This does not mean that it is incorrect and that your axles may be different from this page but believe me one thing with Unimogs are they were mostly custom production units for the 406 models and up.  They were ordered to be anything from an aircraft tug, military vehicles, right up to an expedition vehicle.  What I am leading to is just because the tag on the outside of the axle says it has a certain ratio you really must disassemble to ensure it matches because it may have been changed by someone in its life like Dana axles are here.   Another thing I must state is the fact that there are small differences from year to year on each axle U 406 to U 1700 that is very hard to say things like the axle shaft dia is X and they all have XX spline shafts and pinion because they simply don't all have the same specs.

Here you can see the axle model number listed on the differential casting.  The model numbers are the numbers to remember and use to refer to the other pages listed.

Here an identification tag that will help you figure out what gear ratios you may have in the axles. The important info here is the 22:7 which is the gear ratio for the differential and 27:13 for the portal hubs to give you an overall ratio of 6.527

Another thing that was pointed out to me was the fact that the pinion and axle shafts have the same spline count and diameter.  So this could help you find out what our getting.  Very early models commonly had 18 spline shafts and later models 21 and some even 23.  There are others splines as well but these are more common

There are certain things that are common and they are the tear down and assembly of the differential is all the same (except Torque specs) but they all share common parts in this area as well as the axle tubes themselves all bolt to the differential.

Brake systems there are anything from drum front and rear (many different size drums too with the smallest size allowing use of a stock hummer rim with a modified center to allow for the Unimog bolt pattern).  There are more common disk front and rear with dual caliper front axles and single caliper rear axles.

Here are pictures of the rear disk brakes on a 406 axle.  You can see the rotors (non-vented) and the lever to actuate the parking brake.  You will also notice only 1 caliper on the rear.   This is a U-900 SEE tractor axle that used to be used by the US Military

Here is the front axle rotors which measure out too 14 5/8" (374mm).  But as you can see the calipers themselves stick out quite a bit past the calipers 18" total.

In this picture you can see the RED Circle is for the air supply to the air locker.  The GREEN Circle is for the breather tube.

PINION CONVERSIONS

Without a pinion conversion you will not be able to use a standard driveline with these axles.  The vendors offer yokes from 1310 right up to 1410.  Here are the pinion conversions that are completed by vendors of which I am not going to make a reference to which one is better or worse but I am merely showing there work available at this time I am writing this.  One thing to try and get when you purchase your axles is the torques tubes and drive shafts to help bring down the costs of the pinions conversions.  You don't have them for your axles not a problem, both vendors carry cores but it may cost you more without them. 

Here is the www.exaxt.ca version

Here is www.killeraxles.com version

Things I have found common on these axles which much of it has been threw other PBBer's.

Here are some of the Threads that I recommend viewing.

The steering joints are double cardan which allows them to steer very sharp 50* total.  There is no wheel hop like in a DANA axle and you are only at half of each joints working angle at full lock steering. The steering joints are bomb proof as long as they are not worn out, this is also because the working load is further reduced by the reduction at the hubs.  The only wheel joint I have ever heard of breaking on these was severely worn out, and had been neglected for a long time.   Axles steer approximately 50* at the stock steering setting. The U-joints measure ~ 4.5" across

 The pinion flange to axle center measurement is 18". It could easily be 2" shorter, and with a lot more work could be a few inches shorter yet.  

Brake systems;

There are several different versions available some with disks front and rear and some with drum rears and variations in between. All disk fronts are dual caliper and calipers are said to be in the price range of about $2000 to replace and have to be manually adjusted. Rotors and calipers are 18" Dia and thus requires a 20" rim to be used. 

For my purposes I want to find the ones that come with a 16" drum rather than the 18" disk brakes (from outside of caliper to outside of caliper).  The reason for this is because they are harder to modify to 8 bolt rims and they require the use of a 20" rim.  The are more expensive than the 404 axle and harder to find but they are quite a bit stronger then the 404 version although the 404 axles have larger bearings in the portal hubs themselves.  The axle tubes are 4.5 inches above the center line of a regular axle which provides great ground clearance. There actual weight rating is close to 4 TON. And should be much stronger than a Rockwell.

Photo provided by ZAG Here you can see the locker claw which is located in the passenger side axle tube front and rear and when air pressure is applied the claw slides down the axle shaft to lock the side gears together, and the spring forces the claw back out once the air pressure is removed.

WMS to WMS for axles

Flange Measures (drum brake)
Chassis	Axle		Brake	Installation	Flange	Remarks
sales	model		system		measure "A"
designation					mm
U 800	747	.001	Drum	Standard	1671
U 800 L		.002	brake
U 800 L		.031
U 900	747	.001
U 1100	747	.002
U 1100 L
U 1100 L		.005
U 1100 L		.030
U 600	747	.007			1509
		.009
U 600 L		.008
		.019
Component-set		.014
Fa. Trenkle
MB-trac 700		.003			1660
MB-trac 1100		.303			2323
MB-trac 1300		.301
MB-trac 1500		.302
		.303

Flange Measures (disk brake)
Chassis	Axle		Brake	Installation	Flange	Remarks
sales	model		system		measure "A"
designation					mm
U 800	747	.101	Disk	SA 35 620	1829
U 800 L		.102	brake
U 800 L		.132
U 900	747	.101
U 1100	747	.102
U 1100 L		.103
U 1100 L		.130
419 FLU	747	.410		Standard
U 1000	747	.110			1859
U 1200
		.420			2020
U 1250		.112			1859
U 1250 L		.421			2020
U 1300 L	747	.111			2061
U 1300 L/37		.113
U 1300	747	.200			2240
U 1500		.201
U 1700	747	.204
U 1700 L		.205
U 1700 L/38		.206
MB-trac 800	747	.105			1976
		.320
MB-trac 900		.131
		.320
		.330
MB-trac 1000	747	.310			2020
Component-set	747	.230			2240
Fa. Thyssen		.231
		.232

SPECIAL THANKS GO TO

www.dansunimogs.com

Also the PBB members that added in this

drj

BlueMoose

Zag