Unimog 404 brake issue

[6x6pinz]

One of our members is having issues with the brakes on his newly aquired 404. He has changed the front brake lines and bled the system but still can barely get the truck to stop. He says it takes a long time and a lot of pressure. Is there anything I need to know before I head over to take a look at it. Does the mog require a special type of brake fluid.

 

[cranetruck]

I know nothing about the Mog, but if it was any other vehicle, I'd check the mechanical adjustments (brakeshoe to drum/disc).
Brakefluid is brakefluid, a non compressible liquid, shouldn't make a difference.

 

[steelsoldiers]

Hey Mike,
I used regular old DOT 3 synthetic in my 404. As Bjorn said, the shoe to drum adjustment is critical. I would jack each wheel off the ground and adjust each brake shoe until it touches the drum and back it off a bit. Give the wheel a spin and make sure they aren't dragging. Is his Mog a radio truck with the trailer air control or a troop truck? If it is a radio truck, the rear trailer air control can hold a lot of air since it is the highest spot in the brake system. There is a brake bleed on top of it too. I would start with the air control and then the left rear and then move forward with bleeding. While you have each wheel jacked up adjusting the shoes, have someone step on the pedal and see if it stops the wheel. If not there may be one or more bad wheel cylinders. Also, if the Mog was trailered anywhere in the past, check the brake lines where they cross the top of the axle tubes. Some people chain the axles when hauling trucks. This will crush the brake lines on a 404. My rear line was crushed when I got mine.

Good luck!

 

[Jones]

I've run into pinched steel lines where they run along the axle housing or down the torque tubes. Another odd problem is that the flex lines from frame to torque tubes sometimes delaminate and brake fluid "inflates" the rubber between the layers closing off the inner passage. Since these trucks sit in military salvage depot lots over in Europe for extended periods of time before entering the civilian market, sometimes the brake pistons rust/corrode in the cylinder bores what with the older fluids being famous for absorbing water from the air and repeated fording operations.

 

[steelsoldiers]

Good point about the rubber lines Jones. I forgot to mention that one.

 

[vtunimog]

A few things to consider -

1. Brake bleeding - I find a power bleeder just does not do it for me, Try two people with the old fashioned method of start furtherest from the master cyl- pump bleed pump. Then work back. Do the master cyl immediately after you do the rear right wheel though.
2. Does it have a boosted brake system ?
3. did he check the brake adjustment ? It's a super simple process. Email me offlist and I can give you run down on adjusting.
4. Rubber brake hoses - when were they last replaced ? They will check and cause brakes not to release as well as problems with getting the brakes to properly engage
5. USE ONLY DOT3, DOT 4 is a no-no unless you disassemble the entire brake system and flush.
6. Do you have a manual ? The drivers manual is great and will tell you how to adjust the brakes.


Chris M

 

[No.2Diesel]

Hi VTUnimog,

How do the Russian Ural trucks compare to the 2.5T & 5Tons?? I'm not a big fan of the ruskies' shiite but the Ural has the looks, power, and the performance. How does the reliabililty of the "Candid Yam" engines compare to the Multi-Fuels and Cummins? How much does one run$ in the US and are they hard to get?

Have you ever seen that TV mini-series where actor Ewen MacGregor & his pal ride around the world on BMW motorcycles. When they get to the Siberian "road of bones" they get some help from some guys with a Ural to cross some swollen rivers. I recommend seeing it for the Ural action.

 

[MOGSTER]

404 BRAKES

REPLACE ALL RUBBER LINES MOG LINES LIKE TO SWELL