Just a quick question, I'm hoping.
First off I have a C-700. 24,000 GVW.

The brake pedal has no pressure to it. At the very bottom of the press there is a significant amount of stopping power...but it all comes at once. Locks the tires up and tries to send you packing(out the windshield). I even noticed the driver side rear tires where locked up when I first started to move again. But once rolling they broke free.

What could be causing this? Im sure its a range of this. But I dont know where to start.
Thanks.

Also, Is there a service manual anywhere for these old trucks?

 

maybe it's easy fix.....add some brake fluid. u have vacuum or air brakes ??

 

Vacuum brakes. It's located halfway back on the trucks frame. I can't figure out why it's doing this. I checked the fluid. Seems to be full. The brake fluid was a little thinner than I would like. But it's there.

 

You need to adjust your brakes..

No pressure because theres no resistance because theres no drum to press against..

 

Please re read what you and I both posted. If there was no "Drum" to press against why would I have a problem with brake lockup upon take off?

 

Once locked up, a brake that is so far out of adjustment with possibly over-spec diameter drums might bind in the drum and not return easily.

IMO time to pull a wheel or two and get a look-see.

Brake work is not going to be fun, easy or cheap.

 

well I ment the no drum to press against for the no pressure part of the pedal..

obviously once the brakes lock up your shoe found the drum... And your pedal probably would have some pressure..

 

Brakes that are out of adjustment usually bind when they hit the drum because the piston has to move so far out of the bore that it can get tweeked in the bore, after a while it wears areas faster than others in the wheel cylinder which adds to the problem.. Eventually the wheel will lock up and not release..

Pulling the hub and drum are probably going to be the next step. But you can see if they just need adjustment.. May be that the adjusters are frozen after all this time though.

 

you may need to rebuild the master cyl, and hone it out to get it clean and smooth..........i still have a 3 stone brake hone and spare stones!!!