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passenger rear brakes tighten as I drive

Posted: Sat Dec 24, 2016 7:17 pm
by hobo
I've never encountered this: the passenger rear shoes tighten up against the drums as I drive, until the whole thing can't even be turned by hand with the rear jacked up. I back off the brake shoes, drive some more, and they tighten up again, with under 2 miles of driving. During today's test it started tightening up before I had even parked and used the parking brake, so I'm doubting the parking brake is the problem. I pulled both rear drums and double checked that the hardware is installed correctly against pictures in the service manual.

Any ideas? :thinking

Re: passenger rear brakes tighten as I drive

Posted: Sat Dec 24, 2016 8:03 pm
by 712edf
The self adjusting drum brakes that I'm familiar with would do their adjusting while the vehicle was being backed up in reverse, but even then they wouldn't adjust themselves to the point of locking.

When did this begin? After working on them?

Are you sure nothing is on backwards or the wrong side? Does the other side work properly?

Bucky

Re: passenger rear brakes tighten as I drive

Posted: Sat Dec 24, 2016 8:52 pm
by PwrWgnDrvr
That squeal from the engine is causing the brake springs to straighten out and push the shoes out instead of retracting them! :lol:

When they are locked up, open the bleeder valve. If fluid squirts out and the brakes release, there is a blockage in the line that is holding the pressure. Usually its an old rubber flex line that is swollen shut internally.

Re: passenger rear brakes tighten as I drive

Posted: Sun Dec 25, 2016 4:37 pm
by hobo
712edf wrote:The self adjusting drum brakes that I'm familiar with would do their adjusting while the vehicle was being backed up in reverse, but even then they wouldn't adjust themselves to the point of locking.

When did this begin? After working on them?

Are you sure nothing is on backwards or the wrong side? Does the other side work properly?

Bucky
Yep. I replaced MC, shoes, wheel cylinders, and hardware. I did the front hoses, but not the rear. The other side (driver side) appeared to be working properly, but when I pulled it apart I discovered I had gotten sloppy and one side of the wheel cylinder was not making contact with the shoe, and was pushed all the way out, rupturing the cup. I opened the bleeder, pushed it back in, bled it, took it for a test drive, and...same thing. Other side is locked up. :thinking

Re: passenger rear brakes tighten as I drive

Posted: Sun Dec 25, 2016 4:37 pm
by hobo
PwrWgnDrvr wrote:That squeal from the engine is causing the brake springs to straighten out and push the shoes out instead of retracting them! :lol:

When they are locked up, open the bleeder valve. If fluid squirts out and the brakes release, there is a blockage in the line that is holding the pressure. Usually its an old rubber flex line that is swollen shut internally.
I'm going to try that. I didn't replace the rear brake hose, so maybe it's time.

Re: passenger rear brakes tighten as I drive

Posted: Sun Dec 25, 2016 6:29 pm
by hobo
hobo wrote:
PwrWgnDrvr wrote:That squeal from the engine is causing the brake springs to straighten out and push the shoes out instead of retracting them! :lol:

When they are locked up, open the bleeder valve. If fluid squirts out and the brakes release, there is a blockage in the line that is holding the pressure. Usually its an old rubber flex line that is swollen shut internally.
I'm going to try that. I didn't replace the rear brake hose, so maybe it's time.
Opened the bleeder: no fluid came out.

Re: passenger rear brakes tighten as I drive

Posted: Sun Dec 25, 2016 9:15 pm
by PwrWgnDrvr
Ok, the ONLY way the brakes can be locked up is if the piston seals in the wheel cyl are not retracting, or the adjuster is somehow turning out and locking up the shoes. Easy to see which it is when u take it apart, then figure out why.

Re: passenger rear brakes tighten as I drive

Posted: Mon Dec 26, 2016 10:40 am
by hobo
PwrWgnDrvr wrote:Ok, the ONLY way the brakes can be locked up is if the piston seals in the wheel cyl are not retracting, or the adjuster is somehow turning out and locking up the shoes. Easy to see which it is when u take it apart, then figure out why.
The adjuster was the first thing I suspected. I guess I'll get an assistant to carefully pump the brake pedal with the drum off and see what happens...

Re: passenger rear brakes tighten as I drive

Posted: Sun Jan 08, 2017 7:24 pm
by slick
When mine did that my little hole in the master cylinder was clogged not allowing the fluid to return to the master. It was new, just a piece of debris found it's way in there. Have someone cycle the brake pedal while you're looking into the master to see if you can see the brake piston move back and forth in both holes. Find a small wire or something to put in there to make sure they are clear. It's free and could possibly be an issue. I've also heard of old brake hoses collapsing on the inside restricting flow. Look fine on the outside, but swollen on the inside. Just throwing out ideas. Good luck..