Deuce has hard brakes

[arhoden]

Hey folks,
My brakes are the same whether the air pressure is built up or not (hard, no assist felt). I crawled under the truck and looked at the air pack. It looks brand new and still has the manufacturers tag on it. This truck was destined for military sales but went to auction instead, I believe the airpack may have been changed soon before it was sold.
The brakes stop the truck but you really have to push down hard. Does an airpack rebuild sound like the answer to my problem?

 

[wsucougarx]

Is your Master Cylinder cap vented? have you opened up the back of the airpack?

 

[JohnnyReb]

It may not have anything to do with the airpack.

Sounds like air in the brake lines. Bleed the brake lines and I will bet you a plug nickel that it will fix the problem. If it doesn't, no harm done by doing it.

 

[jim-m35a2]

Is the master cylinder full of the correct brake fluid?
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[JohnnyReb]

Jim make a good point.

Have you added any Brake Fluid?

Do you know the difference in using DOT 5 and DOT 3? You should not mix the two kinds.

Originally the trucks were set up for DOT 5 but over time some people have changed the systems to DOT 3 by purging the system of DOT 5 and during a total replacement.

If your airpack was newly installed or rebuilt, someone may have also altered (or screwed up) the fluid part of system.


BTW: Welcome to another GA member. Where are you in GA?

 

[WillWagner]

Here's a test. Build air and shut the truck off. Step on the brake pedal. If the air pac is working, you'll hear a sound like HHHHH after you let off the pedal. That will be the air venting from the unit. If you hear no noise, the piston is stuck in the cylinder. If you push on the pedal real hard, it might loosen up the piston, but it will piss brake fluid out the vent...if it is still connected.

 

[arhoden]

JohnnyReb you were right! I bled the airpack and it started working. Next I'm going to do a complete bleed on the system since now the brakes feel kind of mushy. Thanks to all for your help.

 

[ironhorsethegeneral]

Welcome to SS Georgia memeber.

 

[ems4ty]

I was going to say the same thing as WillWagner but he beat me to it. Now that you know the problem, time to get a gallon of DOT 5 at the least and do a thorough flush. Stuffs not cheap at your local auto parts store. I paid about $10 a pint when I didn't have the time to search for a better deal.

Good luck and happy trails!

-Tyler

 

[tonidial]

I paid 35 for a gallon at Napa - seems DOT 5 is an oddity elsewhere.

Thanks for the posts tho - have notice the brakes being squishy on my 72 duece, just thought it was age though. Had consider bleeding them, but not all the thrilled at the idea.. Anybody have suggestions on this? Or would I be time ahead to take it somewhere where they have a vacuum bleeder?


I had much breaking improvement overall after replacing a leaking seal on the intermed axle - went from coaster brakes to stopping brakes

 

[tonidial]

correction: 32.50 for a quart at Napa 1 year ago

 

[cbvet]

FYI:
Stuck wheel cylinder pistons can cause a hard pedal too.
If the pistons can't move, pushing the brake shoes out against the return spring tension., there is no "travel" in the pedal.
In the long run, if you're going to keep the truck, I think it's worth the trouble to rebuild all the wheel cylinders.
Eric
CBVET

 

[bugei]

air pack

not sure exactly what you mean by hard peddle, but there is an error in the tm re: the airpack rebuild, and if you make the mistake, the peddle will be very hard AND THE TRUCK MAY OR MAY NOT stop. (WHICH IS BAD!)

if the problem seems to come and go, but mostly be there, the new airpack was possibly rebuilt wrong. i think there is a sticky explaining the error.

 

[Boatcarpenter]

arhoden
Here is a link to a useful Sticky concerning brakes in the old Forum.
http://old.steelsoldiers.com/index.php?name=PNphpBB2&file=viewtopic&t=5469
Also, if you search for Airpack rebuilding threads, you should find some pictures that are wrong in the TM for rebuilding the airpack with the correct way described.
BC