M35 brakes

[WillWagner]

Does anyone know if the air portion of the brakes on an M35A2 doesn't send air to the yellow glad hand when the pedal is depressed, does it effect the braking on the truck? Does the air side boost the braking of the truck side brakes or just operate the trailer brakes?

 

[red devils dude]

ok I think I know what your asking.
Yes the air portion of the brakes on a deuce bost the truck's brakes like the vacuum in a civy car and it
operate's the trailer brakes.

 

[WillWagner]

Well, It looks like i'll be needing to rebuild that too...maybe. Can anyone come up with a reason why the air side doesn't work. It builds air, there is air at the fitting in the cab on the passenger side and at the red gladhand if the valve is opened.

 

[Boatcarpenter]

I'm not exactly sure what you are asking, but it sounds to me as though you may be having trouble with the airpack. May be stuck so that you are not getting any air boost to the truck brakes, but the rest of the system is charged. If it is working you should be able to hear(listen very carefully) air escape if you press the brake pedal and release it. Otherwise, you should at least remove the air pack and disasemble it, clean it and replace any bad rubber parts. Not a bad job.

 

[Recovry4x4]

is this truck a tractor? If it is, there is a possibility that the tractor protection valve isn't working. Mine is giving me fits right now!

 

[Dieselsmoke]

The red gladhand will have air all the time when the valve is opened. The yellow only recieves air when the brake pedal is pressed. To see if it's working properly without a helper, you can build up air, shut the truck off so you can hear, open the valve at the gladhand and press the brakes. If it's working you will hear it.

 

[WillWagner]

It is a troop carrier...I did that, thats when I figured out it wasn't working. I took the "J" shaped tube off of the back co the air pack..no air. Took the supply line off, lots of air. Gave it a squirt of WD40, blew air back thru the junction where the supply line and the "J" tube are...works great now! What a difference, but now the front rubber brake line that was hard as a rock started leaking. Oh well, the hazards of owning an older vehicle! There was a post from a guy that had NAPA numbers for the brake lines. Dont know if it was for the front or the rear, i'll have to look for it and ask.

 

[rdixiemiller]

Watch using WD40 on some air system components. WD40 can swell some O-rings and cause them to stick.

 

[WillWagner]

You know, you're right. I didn't think of that. I hope i haven't made another problem for myself.

 

[cattlerepairman]

hello guys,

I have a problem: my deuce and a half had a low brake pressure ( SPONGY BRAKE PEDAL)

I have revised a master cylinder
I have revised a brake booster
I have new wheel cylinder inside.
I have new brake hoses sit up.

And I can't find the problem with the spongy brake pedal.
do you know something?

I would

• ensure that I bleed in the proper sequence (master cylinder and airpack first, then starting at the right rear wheel)
• ensure that the brakes are properly adjusted (pedal travel is not a lot; a few brake shoes out of adjustment will eat up a lot of pedal travel)

I would also check for leaks, especially the connections between brake lines and wheel cylinders and between flex hoses and brake lines.

 

[emr]

hello guys,

I have a problem: my deuce and a half had a low brake pressure ( SPONGY BRAKE PEDAL)

I have revised a master cylinder
I have revised a brake booster
I have new wheel cylinder inside.
I have new brake hoses sit up.

And I can't find the problem with the spongy brake pedal.
do you know something?

You have forgot one very very important thing, U need a Major Brake adjustment,all wheels, that sure will cause a spongy pedal, I am not syin it is for sure, but it IS important and may fix your problem, 3000 miles after a major a minor is needed in these trucks then 3000 miles a major again, look it up there is good info on doing it in here...