rear brakes sounds like there grinding

ronjon_4 · #1 06-16-2008, 02:54 PM

Well i just replaced the rear brake pads but when I turn the rear wheels it sounds like the pads are constantly touching causing a scraping noise. The noise goes on and off at a regular interval and speeds up when the car speeds up. Thought it might be the rotors so I had them turned and still is happening. Is there an adjustment for the rear pads or something I am missing?

******

94 Grand Prix SE

Hungrycat7 · #2 06-16-2008, 03:42 PM

One of the pins could be stuck. When you changed the pads did you pull the slide pins, clean them, and re grease them?

ronjon_4 · #3 06-16-2008, 05:18 PM

that I did not do. do they require a special tool to get them out?

00GTP4ME · #4 06-19-2008, 04:38 PM

You should be able to get them out with a socket wrench (12-15mm, somewhere around there) and depending on how long it's been since they've been taken out- some elbow grease.

ronjon_4 · #5 06-25-2008, 09:18 AM

well got them out and they looked good but one on each side seemed to be lacking some grease. Lubed them up and put it back together but still seems to be making the noise. Sounds quieter but the pads still seem to be rubbing on both sides of the caliper. Is there a parking brake adjustment that may be causing this or is it just the type of pad and needs to wear in?

00GTP4ME · #6 06-25-2008, 09:53 AM

I've noticed that whenever I put brand new pads on, it takes a few miles to wear them in to the point to where they don't touch the rotors at all. I asked the guy at my tire/brake shop and he said that's usually normal for putting new brakes on. If you've gone a week or two and it still does it, then I'd dig in deeper.
Have you noticed your brakes getting unusually hot? That would be a good indicator if something is wrong.

shenning · #7 06-25-2008, 10:24 AM

Just a thought - is the pad wear indicator installed correctly? The indicator is part of the clip that holds the pads on. I'm not sure that this would cause any problem when the pads are new, but I found this problem on my '99 GT GP when I changed the rear brakes. Had a nasty grinding when I hit the brakes. I noticed the clip was not on the pad correctly when I changed the pads

inafogg · #8 06-25-2008, 02:38 PM

just a thought..is the backing plate rubbing on the rotor??sometimes they get bent when doing this type of job

gaiusmarius · #9 06-25-2008, 06:32 PM

Sounds like it might be a warped rotor, resultant from a seized piston.

mike3381 · #10 06-25-2008, 06:37 PM

Hello, you should check the piston inside the calipers to make sure thy retract correctly. I had a bad piston and ending up putting new rotors and loaded calipers on. mike

gaiusmarius · #11 06-25-2008, 06:51 PM

If it's the piston, the wheel berings might be toast too.

I could cook a steak once with one of those but i caught it 10 minutes after changing in a new rotor, so i got lucky and swapped out the piston.

doctorhrdware · #12 06-25-2008, 11:14 PM

Also it could be that the backplate is rusted and is causing the scraping noise. The rear brakes on my wife truck the back plates are totally rusted out. I wonder if the junk yards would have them or am I going to have to order them. It a Silverado 1500.

ronjon_4 · #13 06-29-2008, 05:23 PM

thanks for all the ideas fellas. Everything looks as far as there not being any rust on any of the parts and the pad wear indicator looks like its holding where it should be. The rotors were just turned and the guy said there wasn't much warping at all. I do not drive this car but a few miles a week so maybe they do just need to be worn in because it sounds the same on both rear tires when I spin them freely. I had to push the piston in when I put the new pads on and the seem to grab just fine. Is there another way to test the piston? I watched carefully as i turned the rotor and as far as I can see its just the pads touching the rotor that is causing the noise. One of the slide pins boots has a small tear in it and both those pins on either side didn't have a lot of grease on them so I greased them up and I think it took away a little of the noise. This wouldnt' be caused by air in the lines would it. I didn't bleed the system when I put the new pads on. As I pushed the piston in I allowed that fluid to be pushed out but after words didn't bleed it from wheel to wheel. Not sure if I can even do that since its 4 wheel ABS.

Again thanks for all your input and any and all ideas are welcome.

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