Hot Rear Brakes 1959

[Pat H.]

I'm having an issue with the rear brakes getting extremely hot and smells like the lining are heating up well beyond normal. So far I've replace the rear wheel cylinders, brake linings, drums, all the hardware and the rear flex hose. These parts were purchased from my local AC Delco distributor. None of these changes have made any difference to the smell of overheated brake shoes or the heat generated from driving. I've also slackened off the parking brake cable to ensure there is no contact on the drums. The front brakes appear to be working, but it's also pulling to the right under hard braking. The master cylinder appears to be okay as it was purchased from Lone Star about 10 years ago. Since there is no proportional valve on these early cars. I can't figure out what else is causing this problem.

Any suggestions would be appreciated.

[Harry S.]

Re: Hot Rear Brakes 1959

Pat, any rubber brake lines to replace? If yes, one may have collapsed, and the fluid can't get out of the wheel cylinder.

[Pat H.]

Re: Hot Rear Brakes 1959

Harry, The rear fles hose has been replaced. I pulled the front drums and had some apply the brake to see if they were working and everything appeared to be working

[Harry S.]

Re: Hot Rear Brakes 1959

Pat, when I did my 63 two years ago, I also replaced everything. I did blow out the brake lines using my compressor to clear them before I put it back together.

[Stephen L.]

Re: Hot Rear Brakes 1959

have you tried to set the brake shoe adjustment looser? Are the parts used for the ebrake assembled correctly?

[David M.]

Re: Hot Rear Brakes 1959

Apply the brakes, release the pedal thren crack a rear bleeder. All within 20-30 seconds. See if it squirts with the pedal released...If it squirts this means the system maintained pressure with the brakes released, which is wrong..

Do the rear cylinders bleed good?
You should get a good squirt with authority whether you use the old school pump the pedal or power bleeder method.

The shoes should be adjusted with slight to no drag, cold.

Lastly, new means nothing today, 10X if its offshore junk.

The bleed test should ferret out a bad new soft line or a blockage in the system from the master. Inspect the hard line.

[Pat H.]

Re: Hot Rear Brakes 1959

David,
It's very hard in finding good quality parts period. I replaced both rear brake cylinders with stainless sleeved original Delco 649's. It seems to bled fine, but I will try and see if what you indicted about the system mainating pressure, which I think it must based on what I've tried. I have loosened the park brake cable as another member suggested and the shoes have no drag after re-assembling them.

[Pat H.]

Re: Hot Rear Brakes 1959

David, I did what you suggested and it didn't squirt out but just dribbled. I think you conclusion is correct that the pressure is not being released. The brake lines were new when I did the body off and have already changed the rear flex hose. Do you have any other suggestions on what to do?

[Stephen L.]

Re: Hot Rear Brakes 1959

Try jacking the rear up so both wheels are off the ground. Pump the brakes a few times, then see if the brake shoe drag has increased. Did you replace the springs that cause the shoes to retract? Did you check to make sure the ebrake mechanism (bars, springs etc.) in the shoe area are installed correctly. Check this against a service manual photo.
I believe there is a "back pressure check valve" located in the master cylinder outlet port that maintains a slight pressure on the line pressure and the shoe retracting springs work against this valve. This keeps a slight pressure on the system that the springs overcome.

I had a similiar problem on my '67 with disc brakes. In my case the check valves are NOT required, but were in the master cyl outlets of a rebuilt master cylinder that I had installed. This caused the disc brakes to not retract fully, eventually causing the brakes to lockup. Letting the brakes cool down for a period of time and the brakes released. It took me a long time to find this problem.........

[Pat H.]

Re: Hot Rear Brakes 1959

Steve,
I went through evenything again today including thaking apart the brake cylinders checking the new springs, The e brake cables and everything seemed to be functioning when I reassembled it. a short test drive went well, but when I went to return home abput 15 miles from my friend garage, the brakes were hot again. The longer the drive the more heat that builds up. I took a temp reading or the rears with the right side indicating 150 and the drivers side at 130. The fronts are at 88/89. I find it hard to believe that the rear brakes are relaining pressure and the fronts appear to be okay. I guess, it might be time to look for a damaged line or possibly a master cylinder. The one I have is from Lone Star that was re-sleeved when I bought it about 10 years ago.

[Rod K.]

Re: Hot Rear Brakes 1959

If I might offer my 2c worth:

First, your brakes are on a single hydraulic system, meaning the hydraulic pressures throughout should be equal at all four corners and the master (barring pinched lines, etc.) which means the master cannot apply unequal pressure to the rears, etc., so I'd say the MC is not suspect. From what I've read here, it seems to me there must be something mis installed or adjusted too tightly in the e-brake system causing the rears to not fully release. I'd take another look at the installation just to be sure all the e-brake parts are correctly installed, then loosen the main e-cable adjustment under the car until you have noticeable slack in the cable. Adjust the rear brakes individually to just drag lightly and evenly side to side (factory service manual for '57 says to back off 12 clicks from light drag for Corvette, 7 for pass) then do a test drive and check temps. If they're down comparable to what you've seen at the front, then readjust your e-brake cable to give slight drag when you apply the e-brake a few notches but be free when fully off and you should be good.

Hope this helps some and good luck.

[Thomas H.]

Re: Hot Rear Brakes 1959

Try jacking the rear up so both wheels are off the ground. Pump the brakes a few times, then see if the brake shoe drag has increased.

Try this, no need to drive around if doing this causes the drag.

Tom

[Thomas H.]

Re: Hot Rear Brakes 1959

I had a similar problem on my '67 with disc brakes. In my case the check valves are NOT required, but were in the master cyl outlets of a rebuilt master cylinder that I had installed. This caused the disc brakes to not retract fully, eventually causing the brakes to lockup. Letting the brakes cool down for a period of time and the brakes released. It took me a long time to find this problem.........

Holy cow - I thought I was the only one that had this problem! I replaced the original MC on my 66 with a "correct" reproduction MC (will send the original out for rebuild and put back on the car). Went to a celebration of life car gathering for a hot rodder that passed way too young, maybe 20 miles round trip. By the time I got home the car would hardly roll and the rims were so hot you couldn't touch them!

Took the new MC apart and what did I find but a residual pressure valve use in drum brake systems - NOT - disc brake systems.

Tom

[David M.]

[Pat H.]

Re: Hot Rear Brakes 1959

Thanks for all the info regarding the e-brake possibility. Las night I slackeded off the park brake cable on both sides so they are loose. I think the park brake may be the issue. Ebverything else has been looked at and checked more than once. All they cylinders bleed properly so it may be the e brake adjustment.

I'll let everyone know one I take it out for another run. Need gas anyway.