Drum brake locks up

[nbpt100]

I just repaired a rear drum brake on my friends mother's car.
All my cars have always had disks so I am not very experienced with drum brakes. I have done a few drum brake jobs but it has been a long while ago.

The problem I found was one leaking wheel cylinder. The lining and drums looked very good. At least a 1/4 of material left. I did look at the other wheels and the front disks looked good and the rear left looked good.

I replaced the leaking cylinder and cleaned everything up with brake cleaner and reassembled. I set the adjuster a few turns back from the drum slightly dragging on the shoes.

After bleeding that wheel I went for a for a test drive and on hard brakes that one rear wheel locks up. The car does need struts/shocks as it nose dives when braking. That may be a factor but I just want to make sure I am not missing anything.

Thanks.

 

[finn]

Lining is saturated with brake fluid, assuming you reassembled the brakes correctly.

Replace both rear sets of shoes. They’re cheap. Brake fluid sometimes turns the lining material to mush.

 

[TarheelMechanic]

Did you replace shoes with new in both rear drums? If not, do that now.
Is the brake hardware put on correctly?

Is the locked up drum causing a pulling condition? In some cases, the problem is not with that drum, it is the other side that is not adjusted properly

Did you touch the outer wheel area after driving and the drum was very hot?

How did you go about adjusting the drums for proper fit?

Post back

What is car/year make model?

 

[Fixin'Stuff]

While it seems like oily brakes wouldn't work at all, oily drum brakes grab hard. Their self-actuating mechanism takes over and locks the wheel. The only fix is new shoes.

 

[larry_g]

A remote possibility is that you got a wheel cylinder that is not the same size as the other one. I know that some axles used under different cars have wheel cylinders that range over a 1/4" by 1/16" steps. Make sure that both are the same ID.. I also agree that you should rebuild both sides with new parts.

lg
no neat sig line

 

[Richard Cranium]

that was my thought, was that he didn't change the brake shoes, and reused the old one.

 

[lilredex]

Before you do anything else, back up and brake hard a couple of times. That is where the self adjusting comes into play. The auto adjusters will set up both side's shoe clearance properly, if assembled correctly.

 

[LS6 Tommy]

If the lining didn't get saturated with brake fluid, is it possible the shoes were installed backwards? There's a leading and a trailing shoe. Reversing them can cause lockup.

Tommy

 

[jimindm]

Not all vehicles have the long shoe on the rear.

I usually do not just put one side on any calipers or WC. I change them as a pair. It very well could be that the one you have changed was working correct all along. The other side in stuck in the bore or not working.

You changed it because of a leak, and I get that. But maybe it went bad because it was doing all of the work. The other side is no working or slow to work, and the other side is working like new.

I would agree on the shoes. If you has a leak, it has likely saturated into the shoes.

 

[seagravedriver]

This happened to me with a 70 Mach 1 Mustang. The parts store sold me the wrong brake cylinder. It can happen at the store counter level, or at the factory. (I recently bought a ring and pinion set, a factory item, and they put the wrong parts in the correct box, at the factory, so it can happen there as well).

You need to replace the brake shoes with new ones, and you need to do both sides.

 

[Spareparts]

New shoes on both rears and also new wheel cylinders on both side, I never do only one side always both, the other wheel cylinder will be leaking soon. Does it have auto adjusting brakes, if so put the drums on snug and then back the car up and brake hard several times like 10 times and they will self adjust evenly.

 

[C_F]

I agree that it's best to replace wheel cylinders & shoes on both sides, not just one side. Also, only do one side at a time, so if you forget where a piece of hardware goes, you can look on the other side to see where it goes.

 

[Spareparts]

I am getting to old to remember where everything goes so when doing brakesalways pop the drums off just a little and flush the brakes out with brake kleen to control dust. remove the drum and clean up everything up with another dose of safety leen then take a picture with my phone. Other taking calls that is all I use my phone for. My wife is always on my *** about that. I dont do text's.

 

[nbpt100]

This is a 89 Olds Cutlass 4 door sedan. I am very confident I put it back correctly. I took pictures before I took it apart. Unless it was wrong to begin with.

I thought about an incorrect cylinder. I went though the applications carefully. The larger bore cylinders have a
7/16-20 thread on the brake line. This one, which is called out for on the 4 door sedan has an M10x1.0 thread. That gives me a bit more confidence it is correct.
I did it by the book.
As the car is being driven the problem is diminishing.

I like all of the suggestions. Thanks to all for the great thoughts and ideas.

 

[KenC]

This is a 89 Olds Cutlass 4 door sedan. I am very confident I put it back correctly. I took pictures before I took it apart. Unless it was wrong to begin with.

I thought about an incorrect cylinder. I went though the applications carefully. The larger bore cylinders have a
7/16-20 thread on the brake line. This one, which is called out for on the 4 door sedan has an M10x1.0 thread. That gives me a bit more confidence it is correct.
I did it by the book.
As the car is being driven the problem is diminishing.

I like all of the suggestions. Thanks to all for the great thoughts and ideas.

That indicates that the contaminated shoe is gradually clearing the fluid. Evaporating from brake heat and/or wiping surface junk off. It may or may not completely resolve itself, and there is a risk of total lockup when panic braking.

IMO, the shoes need to be changed.

 

[Fixin'Stuff]

My experience has been that oiled brake linings tend to grab even harder when there is water on the road.

 

[Rlfd213]

Did you try backing the drum off a couple more turn and see if it stops locking up?

 

[Schurkey]

Before you do anything else, back up and brake hard a couple of times. That is where the self adjusting comes into play. The auto adjusters will set up both side's shoe clearance properly, if assembled correctly.

Not all self-adjusting brakes use this method to adjust.

If the lining didn't get saturated with brake fluid, is it possible the shoes were installed backwards? There's a leading and a trailing shoe. Reversing them can cause lockup.

Not all drum brakes use primary/secondary shoes.

Does it have auto adjusting brakes, if so put the drums on snug and then back the car up and brake hard several times like 10 times and they will self adjust evenly.

Again, not all self-adjusting drum brakes will self adjust when backing up. The "Self-Energizing" brakes of the '50s, '60s, '70s and even later, have been supplemented by other designs.

One of them requires park-brake use to adjust the service brakes. If you don't use the park brake, the service brakes go out-of-adjustment, wear unevenly, AND LOCK UP.

If the adjuster is at the bottom of the shoes, connecting them, and there's an anchor-pin at the top of the shoes--you've got the old reliable Self-Energizing system. If the adjuster is just below the wheel cylinder, towards the top of the shoes, and an anchor-block at the bottom, you've got the "newer" system that requires the park brake to actuate the adjuster. If the park brake does not apply and release properly, the brakes don't adjust. If you don't USE the park brake, the brakes don't adjust. It's a horse-**** system that should never have been invented. Applying the park brake raises (arms) the lever that will turn the adjuster wheel. Using the service brake allows the lever to travel downward, which is what actually turns the wheel. The brakes adjust (if needed) the first time you use the service brakes AFTER releasing the park brake. Many FWD GM vehicles and 1/2 ton trucks use this "twin leading shoe" design. I don't trust it...but nobody asked my permission before installing it on a billion cars and trucks.

Contaminated shoes need to be replaced. The adjuster mechanism needs to be functional, and the park brake needs to be "exercised" frequently.

 

[like2wheel]

That indicates that the contaminated shoe is gradually clearing the fluid. Evaporating from brake heat and/or wiping surface junk off. It may or may not completely resolve itself, and there is a risk of total lockup when panic braking.

IMO, the shoes need to be changed.

This.
Stop screwing around & fix it correctly, before there's a brake stab on a curve & someone gets hurt.

 

[sberry]

Dont panic, millions of cars on the road every day with bad neglected brakes.

 

[meboatermike]

Boy you sure have that right sberry

 

[Bad Eye Bill]

It's been my experience that those GM drum brakes of that vintage in just about all models were very finicky and temperamental in adjustment and operation.

 

[Schurkey]

It's been my experience that those GM drum brakes of that vintage in just about all models were very finicky and temperamental in adjustment and operation.

GM got sued over this style of rear brake on the Damned Citations (GM X-body) because they locked-up. Duh.

Since using the park brake is a dying art, and has been since before this style of brake was popular, needing the park brake to keep the shoes adjusted was beyond silly, it was actually negligent.

 

[ken w.]

If the parking brake hasn't been used and you pull it , it may not release. It could be seized. If the car is a 89 , its almost 30 years old. Your lucky anything back there works. I would also turn the drums. Something that old and in the Northeast , you just replace all that stuff.

 

[Rlfd213]

Ken W. Is correct. My wonderful wife used the parking brake on our 03 caravan once for some dumb reason and that caused a ripple affect. It released enough that the wheel spun but on longer drives the wheel got hot enough to lock up. I didn’t know about it till I said **** it and disconnected the parking brake. When I told her I disconnected it she mentioned she used it about a year ago and that was when we started having issues.