Wierd brake issue

[1 Patriot-of-many]

The first time I push the brake pedal it has a lot of travel, firm at about 2-3 inches off the floor, if I let the pedal rise and push down again it's firm about an inch or two from the top. Is this a bleed issue or airpack or something else?

 

[rlwm211]

If the pedal is solid and the brakes work good, it is an adjustment of the brake shoes that is needed most likely

RL

 

[1 Patriot-of-many]

Yeah they work good and the pedal is solid. Guess brake adjustment is next after finishing the dogbones. Thanks!

 

[bones1]

Getting good pedal on the second pump?. Could be air.

 

[rlwm211]

While I agree that air could be the issue, the first order of business is to make sure the brake shoes are properly adjusted.

Once they are you can evaluate the brake system again and if the two pumps are still required to make them work properly then it could be air.

You have to eliminate the mechanical before you go for the hydraulic.

besides, adjusting the brakes is free. Bleeding the brakes sometimes can be expensive if you cannot recover the BFS entirely

RL.

 

[dodgedougak]

Could also be a leaky master cylinder. Getting a higher pedal after a second or third pump often indicates this problem.

 

[1 Patriot-of-many]

Getting good pedal on the second pump?. Could be air.

The peddle hardness is fine on both pumps, but the first pump has a lot of travel, second is much higher(like where I would expect) Could you expand on that? Can rebuild the master or do I have to replace it?

 

[jasonjc]

The peddle hardness is fine on both pumps, but the first pump has a lot of travel, second is much higher(like where I would expect) Could you expand on that? Can rebuild the master or do I have to replace it?

It sound like too much space between the shoes and the drum. The frist pump pushes the shoes to the drum and befor they come all the way back, the 2nd pump does not have to push out as far. Hope that make sense.

 

[autigers35a3]

Is the air assit kicking in?

 

[hoop]

Adjust brakes.

 

[nk14zp]

Adjust brakes and check brake pedal linkage adjustment.

 

[rlwm211]

how to tell if the air pack is working

Is the air assit kicking in?

If the air assist is not working, you do not have brakes

RL

 

[roger-wilco-66]

If the brake shoes have to travel a long distance to the drum, this is usually accompanied with a distinctive noise that the retaining spring makes (definitly audible as long as the motor is not running...). I found that this corresponds to how far the brake pedal can be pushed until you have a firm resistance.
I once employed a soldier B to intermittently press the brake pedal while I listened at each wheel and so found the culprit in a matter of minutes!

Cheers,
Mark

 

[1 Patriot-of-many]

Thanks guys. Yes air assist works fine. I will start by adjusting the brakes. Appreciate the help.

 

[73m819]

Still think it is AIR in the system

 

[1 Patriot-of-many]

We shall see when I get around to it. Have two of the wheels off already for the torque rod replacement so might as well start on adjusting the brakes. Did the Army NG normally drive around like that if there's air in the system? It's been like like since I got the truck.

 

[hndrsonj]

Did the Army NG normally drive around like that if there's air in the system? It's been like like since I got the truck.

There's no telling how long it sat before you got the truck, things leak air gets in etc. If it's not adjusted right, that didn't just happen, and they prolly drove it like that.

 

[jasonjc]

My ex air force truck does the same thing. You can hear with the eng off, the brakes retrating one by one as the fuild goes back in to the master cyclinder. Not saying this is right but they do work fine. And a brake adjust ment is on my list of things to do.

 

[x-ray]

I have the same symptoms with one of my trucks. Peddle is a little soft on the first press then is better thereafter.

I thought it was odd considering I was doing the whole truck as a project, I have replaced or rebuilt everything brake wise but the air pack itself. (new Master Cylinder, lines, flex lines, wheel cylinders, adjusted shoes fluid, bled 3 times with DOT-5 (manually).

I am thinking my situation is one of two things
1) still some air in it - and I need to get off my but and make a power bleeder.
2) Air pack is somehow leaking air into the system

I will be watching this thread to see if anyone has some other ideas.

Thanks,

 

[Keith_J]

Adjusting brakes may not work. The supplier of wheel cylinders for this vehicle chose to use plain-ended springs on the wheel cylinder assembly. Springs without cup expanders. When not used for a time, the cups will leak as there is little tension to prevent weeping.

This manifests as either leaking wheel cylinders if the boots leak OR an initial soft pedal if the leaked fluid is trapped in the boots.

Overhauling the cylinders with proper expander-ended springs will solve this problem.