Had disk pads and rotors and shoes replaced. Still have the locking right rear plus a new problem: After sitting for more than an hour the brakes grab violently till they have been used for a few stops where the brakes are used firmly. Tires lock up, juder badly and hop. I look silly! Right rear problem is old but the lock up is new.

Ideas?

Thanks,

John

 

So many possible causes

1. Contamination on shoes or drums, oil, grease, brake dust.
2. Improperly adjusted, including parking brake.
3. Improperly installed hardware.
4. Shoes that don't properly fit the drum, usually because the drums have been turned to much/many times.
5. Shoes installed backwards, leading shoe vs. trailing shoe.

 

Super,

Thanks. Everything you have suggested has one disqualiftig factor, I think: My brake grabbing problem happens after a cold soak or over night. After their initial grabbing episodes it all sorts out and the brakes perform as they used to. The right rear used to grab and lock most times under hard braking. now they both do and that doesn't sort out. BUT! The hyper sensitivity after sitting that resolves does go away.

The only thing that seems to make sense to me is that a thin film of rust forms in just minutes and that is enough to cause the brake pads to go nuts with friction when the brakes are first used. But I am the guy with the problem and the opinions of the forum carry more weight than mine.

The disks and pads are new. Did he contaminate the materials with oil or grease? Who can figure people. Would contaminated pads grab on the first use in the morning and then work fine?

I still need help even before I take a wheel off.

Thanks,

John
Please don't think I am screwing with you in any way.

 

So from your statement "disks and pads are new" and referring to the rear locking up, you have rear disc brakes.

One test you can do before to start off in your rig is to loosen the brake bleeder fitting. You don't need to take the wheel off, but it helps.

If the fluid shoots out, then you may have a line problem as the fluid stays pressurized in the line and no way to go back.

If it just dribbles out, the caliper may need to be serviced/rebuilt/replaced as it may be grabbing because of debris in the cylinder.

It's a longshot, but it's a simple test and a process of elimination.

Hope this helps!

 

Actually, I believe dirty pads would allow it to slip...not lock up.

I always use heavy doses of brake cleaner, so I wouldn't really know

 

Everything you have suggested helps and you are much appreciated by me.

I wasn't clear. I have drum brakes on the rear and they are grabbing just like the front discs.

I understand the residual pressure problem you have described and I don't have those symptoms.

The most valuable info I have is that this isn't a "known" problem with a known fix. The crap SOB that did the brake job must have allowed the pads and shoes to become contaminated with oil or grease.

Again, thanks for all your good advice and taking the time to help me.

John

 

No problem.

Then, with this in mind, you will have to pull off the wheel and drum to inspect for contamination.

That's when you'll finally answer that question.

I didn't read if all the hardware was replaced, as well. Maybe something old broke inside wedging it in there causing you grief? Gotta open that drum.

A bad wheel cylinder that will push the pads apart and not disengage?

You can do that same test to find if it's the line or the cylinder. You said you had no residual pressure, then the cylinder may be bad.

The pieces don't cost much but replacing them can kind of be difficult without the right brake tools or MacGuyver skills with a flat screwdriver and visegrips.

Supercab's #5 suggestion of pads in reverse might be something to look at, too.

If you want to check the "SOB"s work if and when you do pull off the drum, this guy on YouTube has a great video to help:

 

 

Yes, with the advent of automatic transmissions, Parking brakes got used less and less

If you have an automatic and you don't use the parking brake daily then make a point of readjusting it once a month, or when you think of it, lol
Hold out the Parking Brake release and pump the parking brake pedal a few times, if should get tighter, that's adjusting the shoes to where they should be, centered in the drum