rear brakes heating up

[rayhandloser]

I have a '67 Belvedere with a 383 4 sp with 10" drums brakes. While driving I was turning a corner the rear brakes dragged me to a stop. I checked the wheels & they were not hot. I drove the rest of the way home. Once stopped there the smoke just poured out from both rear wheel wells. The rear drums were 395 degrees. I removed the wheel & drum & noticed that both the front & rear shoe were expanded out away from the centering post. The drum would not go back on. I bled the brake fluid & the shoes closed allowing the drum to be put back on. I took the car to a brake place were they replaced all the springs, adjusters & hardware & rear shoes. The rear drums were turned. Also the brake line from the front valve to the rear drums was replaced. This includes the rubber hose over the differential. The problem is that the rear brakes still heat up. A short trip will heat the rear to over 200 degrees. The front are always less than 90 degrees. The rear wheels turn freely while turning them off the ground. The rear adjusters are to the point where the brake pedal is almost mushy. I have check the rear end fluid level, even the vent on the top of the rear end. Can anyone think of a reason why this is happening. Thanks. Ray

 

[tpodwdog]

you have everything on backwards would be a guess. brakes are supposed to" self adjust" while going in reverse and hitting the brakes. you possibly have them on backwards and they are " self adjusting" themselves while you are going forward and hitting the brakes.....followin me ?

another guess would be the proportioning valve gone bad.

 

[5.7 hemi]

Remember, the shoes go on like a mullet hair cut, short in the front long in the rear.

 

[ws27]

Sounds like a fluid thing.

Make sure the rear system piston in the master cylinder is returning all the way. If it doesn't, the piston will block the resevoir to cylinder (master) port not allowing expanded brake fluid to go back into the reservoir. Driving will heat up the complete master. Figuring out if the rear system piston is returning all the way will be difficult because it is not attached to the brake pedal rod. Changing the rear hose was not a mistake, they can delaminate which can allow fluid to either not pass at all or pass then not return depending on how it delaminated.

Good luck

 

[1948 santa]

First step in adjusting rear brakes is to loosen the emergency brake cable adjuster,then adjust brakes,then readjust emergency brake.

 

[Cranky]

I hate self adjusters and always took them off....front and rear! I left the star wheel and made the adjuster stud snug so vibration wouldn't make it move on it's own.

 

[rayhandloser]

Brake update. I now have replaced both rear wheel cylinders & the master cylinder. It was actually leaking into the car & the little rubber sleeve / grommet was in two pieces. So it needed to be replaced. The rear brakes are still running hot. Over 200 degrees. The front are also less than 90 degrees. I went to a small car show tonight. I tested my friends '65 Chrysler Wagon @ 80 degrees. A Satellite Sebring @ 82 degrees. The rear adjusters are so loose that there isn't any drag on the shoes. Something is wrong but what. Ray

 

[Sixer]

Adjustable pedal push rod too tight? Disc fronts, and brake pipes connected to the wrong ports? Residual pressure valve installed on wrong port? Anything done to the car just before this began? I lean towards E brake apply, inadvertent or not.

 

[RustyRatRod]

Check to see if there is a residual pressure valve in the system. If it goes bad, you'll get that result.

 

[Dako]

Possibly the brake proportioning valve (down there on the sub-frame rail) malfunctioning?...not releasing all the pressure to the rear wheels when the pedal is let up...causing the rear shoes to drag, thus heating up the rear drums? Just me 'typing out loud'...

 

[tpodwdog]

heres a dumb thought......check to make sure ya got gear oil in the rear end. you can do the math from here!

 

[RustyRatRod]

Possibly the brake proportioning valve (down there on the sub-frame rail) malfunctioning?...not releasing all the pressure to the rear wheels when the pedal is let up...causing the rear shoes to drag, thus heating up the rear drums? Just me 'typing out loud'...

"All" pressure is not supposed to be released depending on the system. If there is a residual pressure valve, it is supposed to hold a small amount of pressure to the rear cylinders to hold them closer to the shoes so that the pedal travel will be minimal when applying brakes. When the residual pressure valve malfunctions, it can cause the problem described.

 

[Dako]

"All" pressure is not supposed to be released depending on the system. If there is a residual pressure valve, it is supposed to hold a small amount of pressure to the rear cylinders to hold them closer to the shoes so that the pedal travel will be minimal when applying brakes. When the residual pressure valve malfunctions, it can cause the problem described.

I was attempting to keep the troubleshooting a bit basic, but thanks for going a bit deeper into the general idea I was trying to convey.

 

[RustyRatRod]

I was attempting to keep the troubleshooting a bit basic, but thanks for going a bit deeper into the general idea I was trying to convey.

Glad I could help.

 

[Meep-Meep]

Check your parking brake cable and related mechanism. If the shoes are away from the upper post I bet the parking brake is somehow getting applied or not returning because the cable is sticky. You should feel a nice spring back return when tugging on the cable from under the car.