The Stovebolt Site Forums The Parking Lot Big Bolts Brakes on 58 Spartan

We replace a couple wheel cylinders and rebuilt the master cylinder. When we took the truck out the brakes built up and started smoking. We opened the bleed screw o a couple wheels and it squirted fluid out. the brakes were okay for a few miles and started smoking again. Had to bleed a little fluid again. How full do I leave the master cylinder? Is there something else I need to look at? 3 of four wheels were very hot. Thanks for suggestions.

Is the return spring attached to the peddle to bring it back to the top, or is it missing and you are effectively riding around with your foot on the brake?

If it does have the spring then the push rod could be adjusted too long, keeping pressure on the wheel cylinders. You would need to adjust it to have a little free play with the peddle at the top.

Grigg

the mstr cyl should be full ..... your rubber hoses are probably rotten - collapsing inside they'll keep the pressure on - otherwise you've done something wrong on assembling the mstr cyl

hey wait! firetruck - hydrovac - if it has one did you bleed it? did you check it? did it get reconnected right?

Bill

Thanks Grig, the spring is attached. You have to depress the pedal maybe 1/3 of the way and it is very consistant. We bled two quarts of fluid until it was clear from each wheel cylinder.
We did not touch the hydrovac, will need to check that monday.
Thanks for the ideas.
Larry

Hey Larry make sure the push rod is letting the piston in the master cylinder return far enough to let the fluid return to the reservoir like Grigg was getting at.
red58 has a good point also, sounds funny but I have seen rubber brake hoses that had rotted on the in side and would let fluid go one way but not the other like a check valve.

If the rubber hoses look cracked, I would replace them anyway. Like most people, I used to only replace them if they blew or were leaking. But last year I helped get a '54 F**d up and running. Everthing was fine with all new brakes until the owner pulled out of the driveway, drove a 1/4 of a mile downhill and stepped on the brake pedal. The front drivers flex hose blew out on the fitting and he had to ditch into the barrow pit. Took about 300 yards to stop. Ever since, I have encouraged everyone to just replace them if they show any small cracks at all. I know this doesn't apply directly to the topic, but seeing a big bolt without brakes isn't something you like to see.

The rubber hoses looked good on the outside but no way of telling what is on the inside. This makes sense, the hydraulic pressure is so much greater than the springs that return the fluid. The truck has eight wheel cylinders, one for each shoe. Thank to each of you for the input.

A rubber hose can cause this problem but it is confined to one front or the rear brakes. I think your problem is in the master cyl or pedal push rod. It is not letting the master cyl. piston go back all the way.

Hey, thanks, I will start with the master cylinder but may go ahead and order new lines to be safe.

I replaced the rubber hoses and rebled the brakes. Still having problems with the pedal building up and brakes won't release. Have to bleed 1 or 2 wheels to relieve them.Anybode know how the vacuum booster works and is ther something to rebuild there?

Back the shoe adjustment off a couple of notches so they aren't rubbing. It's causing heat expansion which applies the brakes more and more the further you drive.
Scott

This truck has a wheel cylinder for each shoe with no provisions to adjust. I now believe the problem is either the slave cylinder at the hydrovac or the master cylinder is bad. will check that angle next.

We removed the master cylinder today and found one of the two holes from cylinder to the reservour was clogged. The larger one (1/4 inch) was fine but there was one about the size of a stick pin that was clogged. Hopefully it is fixed. Thanks again for all the input!
Larry