What are the typical causes of brake squeel?

[Cobra4B]

I got tired of my rear pads squeeling so I replaced them w/ the Delco Ceramics I've had sitting on the workbench for a couple months and bled the brakes. While I had the car up I repalced the 75w90 Mobil 1 gear oil in the diff w/ 75w110 Severe Duty Amsoil. I wanted to see if it would change the slight diff whine I get w/ the 3.90s.... it seems that it may have made it a tinge quieter, but nothing major. It's stil most prominent just over 60 mph when you back off the throttle to maintain a steady speed.

As for the brakes the pads were about 1/2 worn and nowhere close to the wear tabs. The rotors were/are fine with no unusual wear. They're the original rotors and now have 49,9XX miles on them (They still have the star washer bit that keeps the rotors tight to the hub from the factory). The only thing I found amiss was that the rear caliper slide pins were pretty much dry. I re-greased all the slide pins and applied grease to all the points on the pads and fresh pad springs as specified by the instructions on the Delco box.

Took her out about 30 min ago for the shakedown and all is perfect... nice and quiet now. So being that the pads were not worn, what could have been causing the squeeling? They would squeel at normal brake pedal pressure. When using very light pressure they wouldn't squeel and when hitting the brakes really hard they wouldn't squeel. Basically you could hit the brakes lightly and ramp up the pressure until they'd squeel loudly and then if you kept going and really pressed hard they'd stop.

Any Ideas?

-Brian

PS - the pads were the original factory coupe/vert pads from 2003.

[WKMCD]

Brian,

The biggest incidents of brake squeel I've had over the years has been after driving in the rain. Dirty water gets up into the brakes and leaves dust when it evaporates. Leaning on the brakes a little seems to burn the dust off and the squeel goes away. Another source is the pad vibrating in the caliper. There is an RTV for brake pads that goes on the back of the pads that dampen the vibration. I never do pads without it and haven't had any squeel on the vert. I don't drive it in the rain.

[Cobra4B]

Yeah the Delco box comes with silicone grease to smear on the back of the pads and on specific spots on the caliper spring/clip things. I had my own caliper lube/grease (big bottle of it) so I actually followed the instuctions for the first time ever. In all my years of tracking the Z06 and doing brake jobs I never put any grease/lube on brake pads.

So far so good.... 100% silent on my commute in this AM and the diff noise is actually reduced a good bit.

[WKMCD]

Originally Posted by Cobra4B

Yeah the Delco box comes with silicone grease to smear on the back of the pads and on specific spots on the caliper spring/clip things. I had my own caliper lube/grease (big bottle of it) so I actually followed the instuctions for the first time ever. In all my years of tracking the Z06 and doing brake jobs I never put any grease/lube on brake pads.

So far so good.... 100% silent on my commute in this AM and the diff noise is actually reduced a good bit.

Good to hear! (pun intended)

[Cobra4B]

Ok so a buddy on another forum said the squeel isn't the pad rubbing on the rotor in situations like this... it's the pad vibrating in the caliper which is why it only happens at certain pedal pressures.

I could probably install the old pads w/ the new springs and fresh grease and they'd be fine.

[allthrottleandsomebottle]

Sometimes the pads and or rotors pickup crap and imbed themselves.........I have found that doing a new pad bedding in process cured my issues in the past

[Sneaks]

Use the blue latex/rubber substance on the back of the pads. Commonly known as "brake quiet". Squealing is caused by the pad vibrating inside the caliper. Rubbing on the rotor at the right speed, makes the pad vibrate at just the right frequency to make it squeal. The "brake quiet" dampens the frequency, and stops the squeal.
Without it,some pads will squeal like Ned Beatty in Deliverence.

[thegreenman]

My brakes have been squealing since changing my pads, lately really bad. I haven't been able to brake in the pads correctly and figured that was the problem. I read this thread and thought I would check my lub. Turns out, I forgot to lub the front brake parts. I lubricated both front and back and most of the squeak is gone. Now all I need to do is break in the pads and I should be good.

Thanks for starting a good thread Brain.