The Stovebolt Site Forums The Shop Area Driveline Brake Issue on 65 Chevy

I just replaced all of the brakes on my 65 1/2 ton Chevy. The front has disk and shoes on the rear (power). I did a normal, simple and complete job on both axles. All of the air has been bled form the system several times. The issue is, no matter what I do the left rear keeps locking up with only moderate pressure on the pedal. I tried backing off the set of shoes on the left rear only and checking the lines for obstructions or uneven pressure. And yes, the axle seal isn't leaking and the shoes are dry. I've done a lot of brakes but have never encountered this type of problem. The only guess I have is the proportioner valve. Anbody have any clues that would lead me in the right direction short of replacing all of the lines?

Thanks,
Emc901

I think you should "burn" them in a few times first and see what happens. Sometimes things just need to wear together to work properly,
Scott

I tried that too. No luck. If I have to get on them hard for some reason, the back end will start to come around. That's not the way I want to smell the rubber!

Did you have this problem before the new brakes were installed?Is that wheel alot hotter than the rest after you drive a few miles? After you drive a few miles and every wheel is warm and you take your foot off the gas does the truck apear to slow down like it's braking?
A friend had this similar problem with one front disc brake and it was the proportioner valve. I have heard of similar problems with rear drums on one side and it turned out to be the ebrake was the problem.
Just my 2-bits:)

I was thinking about taking the cable off the e-brake but it seems loose enough to not be the problem. It may be worth a try. The proportioning valve is way hard to get to. I didn't install the brake system so I'm not even sure what I would need to ask for to replace it. Are they pretty much all the same on 60-72 models?

Thanks!

I didn't have this problem before I "fixed" the brakes. But they were so far gone, who knows! I 've only had this truck for a few months.

I don't think the prop valve is the problem, especially since you only lock up one wheel. If it had been both wheels, then it could be suspect. One thing I can think of, besides the parking brake cable being too tight, is potentially a hung up equalizer bar. If it's hung up, it will hold the shoes closer to the drum that the other side. Adjusting it down generally won't help. You might want to pop the drum off and see if the shoes settle all the way back with the brakes released. Give 'em a jostle, they might pop back down. In that case, I would suggest lubricating the area where the equalizer bar rides, especially on the side where the parking brake lever actuates against it.

Even though a ebrake cable apears loose that may not meen anything, they stretch and do rust/sieze up after age etc. I'm no pro but I would try driving the truck with the ebrake disconected. If anything it will eliminate one possible problem.

EDIT> Even Better, try what Bill says

I'll try both suggestions tomorrow. I never thought to check the equalizer bar. It sure may be off. I did take the drum back off to loosen the shoes but never thought to check the bar.

It sure could be my "expert repair" causing the problem.

Thanks.

Take a look at the pedal to booster push rod. Make sure it is free and not applying pressure to the system when the brakes are not engaged.
Fred

These shoes we get now are not cam ground. I f the drums are new often the shoes contact on the end & grab. Take the left rear shoes of & see how they fit in the drum. If they contact on the edges they need to be ground. If you have a shop around there that can grind shoes have them cam grind them. If not take a power sander & sand the outer parts down a little. Some old vehicles had adjustable anchor pins that you could loosen up & slide the pin up or down to center the shoe, but I dont think that model does.

Make sure you haven't switched the primary and secondary shoe positions on that wheel. The primary shoe is the short one, and should be the at the front position. The secondary shoe is longer and goes in the rear position. The shoes probably are marked on the edges with Pri and Sec.

If the secondary shoe is in front, you will get more engergizing effect and the back shoe will tend to apply harder for a given pedal force. Beyond that, make sure the anchor pin is secure and the backing plate is tight.

Harvester

just out of curiosity did you turn the drum's ? with new shoes they could be out of round enough to be touchy .they don't do it any more but when i was in the machine shop (old one ) i used to re arch the new shoe's to fit the turned drum's .it used to make a better job in the long run .

I had the drums turned and they are in good shape. I think I'll pull the left rear apart and reassemble it again. Something's probably out of whack or it may just be lacking a good mechanic(that would be me).

Thanks,