Odd Brake Problems

[wiccanferret]

This is a list of everything brake related that has been changed on this car:

Rotors
Pads
Springs
ABS Valve

This is what the car does: Rear wheels will sometimes clamp hard for no apparent reason. Sometimes they also forget to let go. Occassionally, on semi-hard braking, the back wheels will actually lock completely up for no apparent reason. All of this almost ALWAYS happens when the brake system is wet. Three different mechanics have tried to figure out the problem, but to no avail. HELP!

[graden]

this might sound wierd... but when is the last time you E break was ajusted? it might be getting caught up in somthin inder the car

[wiccanferret]

Erm...wow...I hadn't thought of that. I'll go to my mechanic's shop 2maro and ask. Any other ideas tho? I would THINK that one of these guys would've thought to look for something like that...tho ya never know.

[Jason Lesbirel]

I'll tell you, I've experienced the same things, and even once the eBrake is adjusted, the rear brake grabbiness never completely goes away. I think it may be a "quirk" of the car - it's never put me in a dangerous situation though.

Get your tech to clean the rear drums and all the springs and such out with brake cleaner - a dust buildup might be gumming up the works. I noticed a big difference once I had my rears cleaned and adjusted.

[99GrandAMSE]

... take a look at your wheel cylinders as they could be leaking VERY SLIGHTLY causing a small amount of fluid to get on the shoes :(

[4kQuad]

In your first post every thing refered to the front brakes. I'll bet if you look at the back shoes, they are smoth or like 99grandamse suggested there may be moisture on the inside of your drums.

Sounds like its time to change the shoes and make sure the drums are clean.

:penny:

[wiccanferret]

This is true. Okay...what could cause it to only act up when wet, though?

The cleaning thing has been done, and he said everything looked good back there. I noticed a big difference after they were cleaned as well...he even replaced the springs back there for me. It helped a lot...but they still lock occasionally, and it doesn't strike me as a real bright idea to drive around knowing that the brakes could freak out at any given time.

[mikem220153]

I had this very same problem on 2 different N body cars. The first one was a 94 Buick Skylark and the again on my 97 GA. Both times it was caused by defective rear brake shoes. I replaced the drums and shoes with ones from NAPA and it cured the problem both times. The problem was more brake shoes than drums. It's just that I replace drums and rotors on every brake job.

[wiccanferret]

Okay..when it goes in for the body bushings some time this week, I'll get that done. I'll post back and let you guys know. Thank you for your help. :):shoot2: :ghost:

[p8ntman442]

this also happens on my little brothers 95 achieva. dont know what it is though, havent looked at them yet.

[master]

There are two other possibilities that were left out:

1) the rear wheel cylinders are stuck or seizing up so they will need replacing.

2) the brake proportioning valve is faulty so is sending too much power to the rear brakes. This is most noticable in cold weather or when just starting out in the morning. Will need replacing.

Either way, the wheels will lock up in the wet because of hydroplaning effect. There's enough grip in the dry to keep the rears from locking.

[Brad97GS]

Originally posted by 99grandamse
... take a look at your wheel cylinders as they could be leaking VERY SLIGHTLY causing a small amount of fluid to get on the shoes :(

This is EXACTLY what happened to one wheel on my old GA. It was scary in that instance...since only one rear wheel would lock up. It'd try to make the car's rear end do strange things, so I'd have to brake as lightly as possible. Which meant I stayed FAR away from the car in front of me...

The new wheel cylinder fixed it though, and my brakes were good for the next 2.5 years without any more work. I sold the car, so who knows how long the brakes would've lasted...

[wiccanferret]

Wheel cylinder sounds good. The valve has been replaced very recently. It did nothing to help.

[4kQuad]

If it is a rear wheel cylinder is leaking, watch the brake fluid levels, it woun't take long before you get low.

[wiccanferret]

Okay, but i've never seen it leak any brake fluid.

[4kQuad]

The leak may be slow enough that the dry thristy brake pads are drinking it up. Causing them to get a shine on the shoes where they touch the drum. Causing the brakes to grab and brake loose.

Have you rode a bicyle with hand brakes. They work pretty well, then add a rainy day. You know how the bike kind of jumps a little as the pads slip and grab. The car is doing the same thing, wether it's caused bad bad shoes or cylinders.

Then there could be air in the line. Have you had to add any fluid lately.

More ideas...........for you to kick around.

[wiccanferret]

Wheel cylinders are starting to sound better and better. And, no, the car has been doing this off and on for about 100k miles. It has never needed brake fluid except when the pads were changed.

[stamarev]

Has anybody found a cure? I have the same weird thing with my right rear wheel...

[HeyDace]

Try backing off the adjustment in the rear. These n bodies don't like a tight adjustment.