Groaning brakes

[Mac077]

I just changed my rear brake pads and now under very slow breaking they groan! Any ideas what I have done wrong and what I need to do to fix? Thanks!!

[00Beast]

Did you bed them in? Did you replace the rear rotors, have them turned, or did you do nothing to them?

How to bed in brakes: http://www.zeckhausen.com/bedding_in_brakes.htm

[vogie01]

Did you make sure you put the pads in the correct way? I will admit when I was in a rush once, I put the rear brakes back together and put one of the pads in on the wrong side. Switched it around, and problem solved.

[00Beast]

These pads aren't really directional unless you get a model where they're specially designed for one side or the other. I usually just put the squealers back on the same side they came off of, but I don't think it makes a difference unless the pads are labeled, which on these they usually aren't.

[swampthing]

How did you push the piston in? Did you screw it in like you are supposed to or did you force it in somehow?

[Mac077]

Ok, here is what I have found since my first post. They moan/groan just when you lightly push the pedal down not really even engaging the brakes fully almost like when you feather the brake or ride the breaks. They are fine when the breaks are fully engaged with no sound at all. I just replaced the pads. The rotors appeared to be in good shape and I am pretty sure I put them in the right way. I did turn the piston in as directed! I did seat them but not the way the article stated. I did several runs to 30 mph and then slowed quickly without stopping completely. Did this about 10 times and the braking actually feels good.
Again, it just sounds bad when you just slightly put your foot on the pedal. Thanks!

[01bonneSC]

Did you replace the rear rotors, have them turned, or did you do nothing to them?

On a side note:

Never have rear/solid rotors turned.

[Mac077]

Any more ideas on this subject?

[Archon]

Did you lube everything up well? Try adding a light coating of brake grease anywhere the pads make contact with the caliper.

[02ssei]

Did you replace the rear rotors, have them turned, or did you do nothing to them?

On a side note:

Never have rear/solid rotors turned.

is this because the rear rotors are so thin?

where did you get your pads? i've had a bad set of pads on my car before and after jacking up the rearend and turning each wheel i found which side was making the noise. after i inspected the pads i found that one pad wasnt wearing at all, bad composition or something. i changed them out under warranty and the problem was fixed.

[Mac077]

Don't know about the rotor thickness but the pads are from Napa, not the best quality pads but their not on the front at least!
I did lube up all the channels and areas where they move and that appeared to do the trick but I am still getting a little groan once in a while when feathering out to a smooth stop!!

[Mac077]

Ok, I am completely frustrated with this situation now!! I have now replaced all rotors and pads with Napa medium grade, lubed them up well and I am still geting the groan!!! It is not a squeal but a moan or a groan. Kind of like running your finger around the rim of a crystal glass but a lower octave!! I am going to take it out and try the seating method mentioned to see what that does. Would this have anything to do with air in the lines or the master cylinder?? Any and all help is grately appreciated since we have both Bonnies down right now and are basically without a trustworthy car!! Thanks,

mac

[Archon]

There is an old TSB regarding the problem.

Bulletin No.: 00-05-23-001A

Date: September, 2001

TECHNICAL
Subject:
Rear Brake Moan/Hum Noise During Brake Apply
(Replace Rear Disc Brake Pads)

Models:
2000-2001 Buick LeSabre, Park Avenue
1998-2000 Cadillac Seville
2000 Cadillac DeVille
2001 Oldsmobile Aurora
2000-2001 Pontiac Bonneville

Attention:
This repair DOES NOT apply to rear brake grunt/groan, pulsation or squeal.

This bulletin is being revised to add a model and to update the model years. Please discard Corporate Bulletin Number 00-05-23-001 (Section 05 - Brakes).

Condition

Some customers may comment on a moan type noise coming from the rear of the vehicle when applying the brakes. This condition may be more prevalent during city stop-and-go or mountainous driving situations. In rare cases, this moan type noise can also occur during the first or second application of the brakes when the brakes are cold.

As the vehicle slows down from 48 km/h to 0 km/h (30 mph to 0 mph), the rear moan type noise may produce a low resonating "hum".

Cause

This condition may be due to pad vibration being transmitted to the caliper assembly resulting in a low frequency resonance.

Correction

Replace the existing rear disc brake pads with a new rear disc brake pad service kit.

The new rear disc brake pads will reduce the vibration being transmitted to the caliper assembly.

It lists the replacement part as 18043999, which apparently has been superseded. This is a link to one place selling them. There may be cheaper ones.
http://www.rmsautoparts.com/proddetail.php?prod=171-642

[Mac077]

Sorry Archon but I just got through replacing all 4 rotors and pads! I just took it out this morning and did the seating as described above or as close as I could come anyway so we will see what that does. This is just frustrating the heck out of me...

[Mac077]

...well I did a second bedding as described and it is still moaning and groaning like a banshee?????????????????? Has anybody else had this problem and what the hell did you do about it??? Please.......................................

[01bonneSC]

Never had the problem.

[00Beast]

Precisely when does it happen? When applying the brakes at 10 MPH? At what speed does it go away?

Have you replaced the clips and the slide pins? You can get a "hardware kit" at your local parts store, might be worth a shot.

[Mac077]

At all speeds but usually when it heats up a little bit. You can pump the brakes and it is less severe but it never goes away. If I can anticipate the stop and stop like an old lady, very lightly braking for 100 yds before the stop then I can avoid the groan, or as my Son calls it, the whale sound! They have new clips but not slide pins but I lubed them up pretty good!

[Roadtech195]

Question.... how are your wheel bearings? I had a left front bearing go out on my bonnie and it didnt make much noise till I applied the brakes or turned.

[Mac077]

Not a bearing...it is in the rear both sides! We have narrowed it down to either bleeding the lines or of that it isn't then rebuild the calipers! Beyond frustration...gearheads can you put your heads together on this one?? Thanks!