rear brake locking up where to start

[JR-39D11]

So after driving in heavy stop and go traffic to get to a car show my rear drivers side brake locked up. What I first noticed was it seemed to stop very quickly I pulled over to get gas and noticed that the brake lights were still on and it wouldn't roll. After waiting and moving the car bac n forth the brakes released. I went back on the freeway and soon my peddle was rock hard and I could smell brakes, pulled off and the rear drivers was smoking. I'm in the tow truck now and looking up things to try. i have new rubber lines and I never touched the rear brakes I think there both sticking but definitely the drivers side is worse also by the time the tow truck got there my brakes where fine. I'm guessing some mc issue but looking for advice on what to check?

[ledfootslim]

Well, not sure if this applies to rear brakes, but I had the exact same thing happen to my front right wheel. Turns out, the pad had shucked off the shoe and doubled itself up between the shoe and the wheel. I woukd give anything for a picture of my dads when I took the wheel cylinder off and peices of pad started falling out........priceless. Anyway, hope you can find and fix your prob and get cruising soon!

[Niel Hoback]

Time to check your brake pedal push rod adjustment. Take off the MC cap and see if you can put a fine wire thru the tiny hole towards the front in the bottom of the reservoir. Shorten the pushrod if the hole isn't open.  Plan B, your rear wheel cylinder has a sticking piston or a shoe is binding on the backing plate.  I'm betting on the MC adjustment.

[47 2 Door Coupe]

Your master cylinder isn't fully "releasing" meaning the piston isn't returning to the neutral position (could be a push rod adjust as previously suggested) releasing the the system fluid pressure or the same thing is happening in the wheel cylinders. The wheel cylinder piston(s) is jamming in the bore due to residuale water in the system from sitting or needing a change?   Good Luck!    Bruce     47 2 Door Coupe

[Barabbas]

I had the rear brakes on my '70 cuda lock up --turned out it was caused by a clogged vent on the axle; the pressure build up caused lube to blow past the seals and all over the brakes.

[Mark Haymond]

I think the master cylinder is the place to start because you said the brake lights were on when it locked up. There was pressure in the lines to make the lights stay on.

[greg g]

Is your brake pedal free play within specification?  Insufficient free play will not allow braking pressure to be fully released.  A dragging brake and heat buildup will cause lockup if the brake adjustment on one side was a bit tighter than the opposite side.  

[JR-39D11]

Thanks for the advice. I'll be able to start working on it this week and will report back.

[BigDaddyO]

Time to check your brake pedal push rod adjustment.   I'm betting on the MC adjustment.

Why would the push rod go out of adjustment?

[Niel Hoback]

Someone didn't tighten the locknut.

[BobT-47P15]

Several years ago, when my rear brakes would lock up if you pushed the pedal harder than normal, it turned

out to be the old rear brake hose.  Looked perfectly good on the outside, but the inside was collapsing and

not letting the fluid return to the M C.  

 

Original poster said he had replaced his hoses.......so I would presume that included the rear one.  

There is a vent on top of the rear axle housing that does get gunked up over time and can be cleaned

up.  I would release my hung-up brakes by opening the bleeder briefly and letting out a little fluid and

reducing the pressure.  So I carried a wrench with me at all times then.  Replaced rear hose.....end of

that problem.   

 

Several good ideas have been presented.........good luck with your fix.

Edited August 5, 2014 by BobT-47P15

[Don Coatney]

It is possible the vent hole inside the master cylinder could be plugged up. The vent hole is the one pictured below with the prick punch inserted.

 

 

 

[Dan Hiebert]

That happened to one of the front brakes on my car several years ago.  Turned out to be that one of the return springs had broken.