Rear drum brakes and I have replaced the shoes, springs and brake cylinder on both rear brakes. Now, for the 3rd time, I am replacing everything on the drivers side rear brakes. When the brakes are applied the brake cylinder is pushing the brake shoes out, as expected, and the passenger side shoes retract when the pedal is released but the drivers side does not retract. Any ideas as to what could cause this on one wheel only?
There are a few things to check. First, are you checking if the shoes retract with the drum off? If are, be very carful not to apply to much pressure or the pistons will come out of the wheel cylinder. BTW, I am not suggesting you do this.
Second, did you resurface the drums? If so, a rough drum can cause brake shoes to stick.
Third, if all of the springs are not installed correctly it can keep the shoes from retracting, this could mean a backwards spring, backwards adjuster, etc.
Fourth, did you grease the adjuster and shoe contact points on the backing plate?
Thanks for the reply, we did apply brakes with the drums off, carefully. Passenger side extended then retracted somewhat when brakes were released. Drivers side extended and stayed in that position when brakes were released.
With this brake setup, there is only one way it can go together. It only has one spring.
Does it have the spring that goes from one side to the other almost in the middle of the drum, it is probably about a quarter inch thick, maybe a little thicker? It would be a tensioned type spring setup, not a coil spring.
Yes, on the tensioner spring. It is located just below the brake cylinder. That is the only spring on this set up.
I had an issue where one of my rear calipers would lock up, trashing the brake rotor and the brake shoes on that side. To make a dime novel a short story, the apparent culprit was my brake hose. We believe it was breaking down internally, and not allowing pressure to release to that wheel. It seemed to happen only during hard braking.
bhn22 Thanks you're the 2nd to voice that one. Will try replacing it.
X2 on the brake hose if everything else I mentioned checks out. The hose bracket rusts where it touches the hose, even when the visable of the bracket is rust free. Replaces both sides if you do this.
Changed the brake hose, doesn't seem to solve the problem. Any other ideas?
Parking brake cable stuck? make sure its pulled all the way back squeeze the arm with a big channel locks or try disconnecting
From there determine if its hydraulic pressure or mechanical holding it up open the bleed screw and see if they release if they do follow your lines up there is a valve inline right in front of the lr tire I don't think I have seen them stuck loosen the line nut there if its not to rusty work your way to the abs unit pumping it up and releasing the line pressure until you find were it is holding up at
If the bleed screw didn't release your brake then something is holding up in the wheel cyl, shoe setup or parking brake
The auto adjuster on the bottom. Try screwing it in a little. There should be a rubber plug right behind it. Put the drums on and check it with the brakes on. Use a regular screw driver to adjust it till it releases.
If this does not work screw the adjuster back to where it was. It might take 5-6 full turns.
Thanks for all the tips. Auto adjuster on the trouble side is all the way in and out about 3/8" on the other side. By opening the bleeder screw, it releases the brakes and the same is true with the fitting just in front of the tire. I will work my way to the front of the car.
It looks like you've determined that the brake on that one wheel is staying locked hydraulically and not mechanically, which was the first thing I would have suggested to eliminate after reading the OP. If it immediately releases after cracking the bleeder screw and the fitting "upstream" of the rubber hose you just replaced, then I think "working your way to the front" is the right path. I'd just check at the ABS hydraulic control unit itself, there should be stampings like 'LR', 'RR', etc. in the aluminum block that all the brake lines screw into to help identify which line goes to what. It's very possible that a the "dump" valve for the LR is stuck and that pressure is trapped between the LR accumulator in the HCU and the LR wheel cylinder instead of the accumulator being blocked off (as normal) by the dump valve and pressure being allowed to 'vent' back to the master cylinder reservoir when the brakes aren't applied.
If you have HCU problems it usually = big dollars and a shop that has a real technician and scan tool to correctly diagnose and bleed the system after repairs. That's not a DIY driveway job unless you have access to a scanner that can bleed GM systems and a little knowledge of the procedures involved.
If you don't find the problem in the line between the HCU and the rear (like pinched shut from bottoming out on something, or severely rusted internally, or a torn flap in the flexy stainless overbraided rubber section near the HCU acting like a check valve), try putting it back together, manually bleeding that corner, and going out to a remote area with grass, snow, gravel, or something loose and make some HARD, ABS stops from about 30 MPH. You want that pump to run and the pedal to kick. Hopefully, if the problem is in the HCU, that might shake it loose.
Gear
Yep say a few prayers and mash it down. You might get lucky.
Check the pads on the backing plate for groves.
Sometimes, on older cars, the shoes will ware a grove into the pad.
The groves keep the shoes from retracting all the way.
Possible bad wheel cylinder????
You changed it, but sometimes......
I think this car has ABS. If it's 4 wheel ABS, it maybe the ABS unit up front.
I don't think it had 4 wheel ABS because of the rear drums. But you never know.
When you open the bleeder screw, dose fluid squirt out???
Do the shoes go back in when you open the bleeder????
Looking at a picture of the system, it uses one of those "horse shoe springs" that retract the shoes.
Make sure it's not cracked, or has lost it's tension, or has been stretched to wide.
Make sure the ends are in the correct holes.
Abunaitoo, thanks for the response. No grooves, I've had 3 new wheel cylinders on it, it does squirt fluid when I open the bleeder. The horse shoe looking spring is in the correct holes and is also new. This is the 3rd time I have replaced the wheel cylinder, horse shoe looking spring, brake shoes and adjuster spring. Each time one of the wheel cylinder pistons are shoved completely out of the wheel cylinder, the horse shoe looking spring is stretched out 1 1/2" and the brake shoes pads are completely gone on the left side. Other side is still good.
Last edited by elkhuntfever; 02-04-2015 at 10:34 AM.
Does it squirt out, or just dribble????
Try and compare how is squirts on both sides.
Put the drums on, press peddle a few times, open bleeder. Do same for other side.
Should be squirting the same.
If it squirts more on the left, something is holding pressure.
Looking on-line, I see it may have ABS.
Could be the ABS unit or the proportioner.
You have two separate proportioner valve on each rear wheel.
Left one could be bad.
Attachment 129320
I hope the picture comes out.
Your system may look different, but it's basically the same.
As you can see, each wheel brake system is separate in itself from the ABS unit on.
Is the ABS dash light on????
If it's on, you might be able to have it scanned to help find the problem.
I suspect the left proportioner may be sticking.
I'd try swapping the left and right to see if the problem moves.
Don't let the fluid run out. You'll get air bubbles in the ABS. Bad, bad, bad.
If not, probably the ABS unit.
ABS problems are a pain to fix.
It can also be very expensive.
Altho it has been almost 30 years since I worked on brakes your problem screams rusted L emergency cable.
Remove the cable from the shoe and I will bet a slightly used loob gruve that the brakes will work great.
WE WON. WE BEAT THE MACHINE. WE HAVE CCW NOW.
rear drivers parking brake cable or possibly a driver side rear brake hose ! if the brake releases when you open the bleeder on the rear wheel cyl ? thats it.
I have worked my way forward from the rear toward the front. Each time I open a connection it releases the brake shoes. At the proportioner valve when I open the connection on the side toward the rear of the vehicle the brakes release but on the side toward the front of the vehicle it does not release. Not sure how the proportioner valve works, could this be the problem and what is the fix? Local auto parts stores don't carry these valves.
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