PontiacBonnevilleClub.com

1999 Pontiac Bonneville. Purchased everything brand new for the rear brakes and even had the work done by gm garage and when I'm close to 5mph and under getting ready to stop I start hearing metal on metal. .... it's associated with the rear brakes only. ..
They've looked at it twice and cleaned the system, but .nobody can figure it out. ... I don't know what to do. ...brand new parts, springs, wheel cylinders, new rorors... everything new... the pads are equal in length for both sides.

Look for other parts rubbing. There was a point my EBrake cable was rubbing on the center hub, but it was hap. Also check to make sure they are properly adjusted, and centered.

Also check for a failing hub bearing in the rear.

if its drum, there may be some sort of backing plate mud guard - may be bent and touching the drum.

take wheel off and spin it by hand - get helper to brake and find the issue - back off the adjuster and see if it helps.

I'd check the dust shield for rubbing where it fits into the "groove" of the brake drum.

Did the problem occur before the rear brakes were serviced or did it begin immediately after the work was done?

RJolly87 wrote:Also check for a failing hub bearing in the rear.

x2

The problem was occurring before I bought all new parts. I bought all new parts and had them installed. Took car back cause same noise from 20mph to stop. They replaced brake shoes with new ones for free. .. left and problem started again. I'm taking it back Wednesday again. I even watched them do the work. I'm just totally lost.

Dumb question but how do you back off the adjuster? What direction?

The very first thing that should be done is to pinpoint which wheel the sound is coming from.
Once in a while, people are fooled by front brake noise seeming to come from the rear.

From the hole in the backing plate, the adjuster would be moved upward AFTER pushing the adjuster lever slightly away from the adjuster with a very thin screwdriver.
Of course, with the drum removed...from the hub side, the adjuster would be moved downward after pulling the adjuster lever away to allow the adjuster teeth to pass it.
Illustrations here:
https://www.justanswer.com/pontiac/1x0w ... -rear.html

I hope it's correct to assume that the points on the backing plate where the shoes pivot and slide have been cleaned and lubricated.
Did you replace the drums (you mentioned rorors?) ?
Assuming the drums were replaced or machined, then it should either be a bad wheel bearing or the parking brake cable is improperly positioned or there's a bend in the backing plate that scrapes against the drum.
The latter should be repairable with pliers.
If the drums were not replaced or machined, an out of round drum will cause issues.
If it's the drum scraping on the backing plate or the parking brake cable contacting the hub, any mechanic should easily find the problem by first isolating it to a single wheel and then looking for shiny metal.
In either instance, I'd expect the noise to be present whether the brakes are applied or not. Same for the wheel bearing, if worn.
The only other possibilities that I can think of are a parking brake cable hanging up which this should be noticeable by considerable heat emanating from one wheel.

Best to have the mechanic take a drive with you, so you can point out the noise, in case he hasn't heard it.

wpbrink wrote:Dumb question but how do you back off the adjuster? What direction?

I spin the drum - see the resistance

turn the gear one way - put back drum and spin - is it looser than before?

if yes, keep spinning in same direction.

So wheel bearing tho?

Update. So they put new pads on the rear but now the abs light is on. Could a sensor be bad in the rear wheels or I see something about an abs module located in the engine area. How do I test these points?

there should be brake pressure proportioners on both rear lines -is the one for that drum there?

small metal canister mounted inline

I will have to check. .. thanks for the tip

I wanna throw a question out there on the rear brakes and the abs light coming on. Let's say I completely disable the abs system. Is it harder on the rear brake system with it disabled? I know the importance of the abs system but I'm trying to do a process of elimination before I buy parts. One reader suggested the wheel bearing be replaced due to a rear bad sensor. I honestly don't know where to start between the abs module or the bearing. Would auto zone be able to pull the exact code?

Disabling the ABS system will cause your car to fail an annual safety inspection in some states.
You will also then have the brake warning light on ALL the time, potentially failing to alert you if a brake issue arises.
As far as brake operations go, your brakes are most often operating without ABS.
ABS only operates when it senses that one wheel is turning at a different speed than the others

Auto Zone can probably retrieve the code with their scan tool.

The dealership put new shoes on and returned the car to you with the ABS light on OR did the ABS light come on a few days later?
Take it back and tell them to fix it for free, if it's the former.
Repairs are not supposed to create new problems---and when they do, it is the repairer's responsibility to determine what the cause is and how to fix it.
If the ABS light was off before and left the shop with the ABS light on, they may have broken a wire to an ABS sensor.
The dealer can very easily read the code that is causing the ABS light to stay on.
The TECH2 will list which wheel, if any, is causing the ABS code.

I'm sure the dealer did not remove your proportioning valves.
Those are attached in-line to the brake lines just before each rear wheel
https://www.rockauto.com/en/catalog/pon ... valve,1888

It is possible that a wheel bearing is going bad---causing the noise and the ABS light to come on.
Get the code read, check the wires and connector at the wheel sensor that the code indicates, if it's a wheel sensor code.
If the wires/connector look OK, replacing that wheel bearing should solve the troubles..

There are separate lights for ABS failures and other brake failures, such as low fluid. I've seen them both in action.

J Wikoff wrote:There are separate lights for ABS failures and other brake failures, such as low fluid. I've seen them both in action.

Yes, but I believe that disabling the ABS will trigger more than just the ABS light--as it does on the 2000 +up Bonnevilles.
"Service Stability System – TRAC OFF, ABS & BRAKE lights are on" taken from http://www.pontiacbonnevilleclub.com/fo ... 25362.html
If I'm wrong, then I hope someone who knows for certain will chime in.

It only triggers the abs light on 92s, I can tell you that much. We didn't have stability control to worry about.

J Wikoff wrote:It only triggers the abs light on 92s, I can tell you that much. We didn't have stability control to worry about.

my 92 GTP had abs and traction control only.......

check to see if the wheel sensors are unplugged or damaged for abs light