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Discussion Starter · #1 ·
Got my 2008 G8GT used at 42xxx miles, "new" brakes all around, new tires...the dealer
“fixed everything” before I picked it up. Now has 54xxx. After I took delivery I brought it to a local shop I trust for a once-over, says things look good.

I put about 3,000 miles on it, I noticed drivers front brake squeal and a clicking at low speeds before a stop. After several “diagnosis” trips to the dealer they finally replaced pads, lubed caliper parts, found rotor was warped – new rotor.

About 3,000 miles more, the squeal was back, random as to when it squeals. But a grinding noise now too, slight pulsation, dark grey discoloration band around the rotor…new dealership found that the rotor runout was way over max. New rotor. New Caliper too.

Now about 5,000 miles more, the rotor is pulsing, again, at varying speeds. Random squeal, no grinding. But I’m out of Extended Warranty so I’m gonna be working on this myself now.

I really don’t know what else to replace. Not sure if I should pony up the dough and get aftermarket rotors? Or is this a caliper issue?

Never had any problems with the rear, just the drivers front.

*sigh
 

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I had the same issues around 15-20K miles with my stock rotors and quite a few other GT owners have also. Some change to the same size aftermarket rotors. I upgraded to take off Camaro SS rotors and calipers a couple years ago and have not had any warping since. I would suggest staying away from the stock factory GT rotors when you change them out on your dime this time.
 

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Discussion Starter · #3 ·
I had the same issues around 15-20K miles with my stock rotors and quite a few other GT owners have also. Some change to the same size aftermarket rotors. I upgraded to take off Camaro SS rotors and calipers a couple years ago and have not had any warping since. I would suggest staying away from the stock factory GT rotors when you change them out on your dime this time.
Hmm. Never looked into the Camaro SS swap... is it a direct replacement?
 

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HeapBlaster
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i'm going to say its not warped rotors but operator error... usually its deposits built up from the brake pad baking onto the rotor after a full stop... in order to warp a rotor you've got to do some pretty ridiculous stuff... put something like a Hawk HPS on the car and you'll likely not have an issue... the grey band you're seeing is pad material... when you bed in your brakes properlly you'll have that at the end of your bedding procedure, its pad material being deposited into the pourus rotor.
 

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Rotors don't warp. It is pad deposits that cause the chattering. You should check runout on the rotor to make sure it is square on the hub face.

New rotors, quality pads and a proper bedding procedure should fix your issues.
 

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You don't need to spend DBA money on rotors. Plenty of good aftermarket options out there.
 

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Something isn't right, the stock rotors aren't that bad.
Make sure everything is in correct order (working right and installed right) calipers, pads, etc. Try new pads to go with the new rotors and bed them correctly, I've found pads and rotors kind of "marry" to each other, swapping one and not the other can lead to premature wear but this is odd.
A competent tech at a dealership should be able to resolve the issue.
You're doing things like spraying hot rotors with cold water?
 

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One huge important factor is braking technique. Don't scoff but being in the Auto Service industry and I see a lot of the strange and unusual when it comes to brakes one thing tends to be a huge factor, being light on the brakes. If you light foot it this can lead to problems fast of squealing, brake dust build up, etc... You have to get ''firm'' with the brakes every so often once you've set them in after the first five hundred miles. If you're not you're setting yourself up for problems quickly down the road no pun intended.
 

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Rotors don't warp. It is pad deposits that cause the chattering. You should check runout on the rotor to make sure it is square on the hub face.

New rotors, quality pads and a proper bedding procedure should fix your issues.
Really? My brake lathe begs to differ. It turns 50-60 rotors per week. And it removes metal, not pad material.
 

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Car RamRod
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Really? My brake lathe begs to differ. It turns 50-60 rotors per week. And it removes metal, not pad material.
right. I've heard that old "it's built up pad material" BS before. ANYONE who has actually turned a rotor back to true condition will affirm that they do indeed warp. And once heated to a point that they warp (see also "Wife driving"), even when turned they will likely warp again quickly. As Feng stated, go with a high quality cryo treated rotor, preferrable USA made blanks. they have better heat dissapating capabilities. This is not the only solution, just the one that fits most folks.
 

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The cause of it is the Crap stock pads. Turn the rotors if the are still in spec and replace with quality pads and your warping and vibration won't come back. You also have to replace the clips and seals on the caliper pins. Then they will be like new.
 

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Discussion Starter · #13 ·
Thanks for all the info guys. It looks like I'll be replacing the fronts at least. I called the dealership and they said they wont even look at it since I'm out 2k over the certified used warranty (well, unless I pay).

I just find it strange that it's only one side, drivers side, that has recurring issues.
 

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First off do not work on it.... Since you have been there already twice with the same issue, go up to them and say hey i have had this same problem multiple times in a row and every time im coming back to get it fixed and its still not working properly. Since they would see in there records that it is a recurring problem they should cover it. Thats what i was told by a deal up north, I could be wrong but its better to go to them when its a recurring problem. If you deal with it than any point after that the fault lays in your hands.
 

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Just a couple informative reads for you. I just replaced all my pads with Hawk HPS, and had DBA rotors from a previous owner. I had the "warped rotor" syndrome also, heavy pulsing while braking. I specifically know when it happened, it was a 110 degree day in downtown Atlanta crusing along the interstate at 80mph when traffic just stopped. I mashed the brakes and got stopped in plenty of time, but just sat there then without moving for 5 or 10 minutes. Brakes pulsed ever since.

I read all these sites about other pad build-up, and decided I'd take my chances with just new pads before I bought new rotors for $100+ each. I scuffed the rotors with 80 grit sandpaper, installed new pads... and vibration gone. Not to mention these pads bite like twice as hard as the old ones. Better brake feel, better stopping power, no vibration... all for like $150.

I don't know for sure rotors don't warp, I just know this worked for me. I would assume also that if you're having them turned down, you could just as easily be cutting off the excess pad material as the rotor itself, they probably both appear as metal shavings coming off the lathe? I'd probably still recommend if you're running stock rotors to upgrade them, especially the front.

http://backfires.caranddriver.com/posts/837-brake-rotors-don-t-warp

http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths
 

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Thanks for all the info guys. It looks like I'll be replacing the fronts at least. I called the dealership and they said they wont even look at it since I'm out 2k over the certified used warranty (well, unless I pay).

I just find it strange that it's only one side, drivers side, that has recurring issues.
Wow!

Extremely sorry to hear about this situation. We would appreciate any updates you can provide on this if it gets fixed or gets worse.

Regards,

William R.
GM Customer Care
 

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Discussion Starter · #17 ·
Wow!

Extremely sorry to hear about this situation. We would appreciate any updates you can provide on this if it gets fixed or gets worse.

Regards,

William R.
GM Customer Care
Thanks William. I did mention that the brakes were looked at in the fall, and it seemed the service guy on the phone knew me and the car, but he was pretty insistent about not doing any work "for free" because I was no longer under warranty.

Perhaps I overloaded him? because I also mentioned that my hood latch cable broke, and the gas cap is causing a cel randomly.... I mean, I do feel bad because it was already in the shop twice for brake repairs... And now it's the same thing. They probably think I'm nuts :-(
 

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Thanks William. I did mention that the brakes were looked at in the fall, and it seemed the service guy on the phone knew me and the car, but he was pretty insistent about not doing any work "for free" because I was no longer under warranty.

Perhaps I overloaded him? because I also mentioned that my hood latch cable broke, and the gas cap is causing a cel randomly.... I mean, I do feel bad because it was already in the shop twice for brake repairs... And now it's the same thing. They probably think I'm nuts :-(
Don't feel bad,

It is our first priority to ensure your vehicle is operating as designed. We appreciate your communication with the dealers in regards to what you're experiencing with your vehicle. Dealers are dependent on the warranty parameters for coverage but generally we look at each concern on a case-by-case basis. Please do keep us posted on the status of your concerns.

Kind regards,

William R.
GM Customer Care
 

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Thanks for all the info guys. It looks like I'll be replacing the fronts at least. I called the dealership and they said they wont even look at it since I'm out 2k over the certified used warranty (well, unless I pay).

I just find it strange that it's only one side, drivers side, that has recurring issues.
That raises a red flag for me. Tells me that it is building heat for some reason. Could be a bad hose, caliper sticking, improperly lube slide pins.



Quick little side note. My dad's '11 2500HD was getting a hellacious brake pulsation after pulling a trailer and driving for a while. Let it cool, and the vibration was gone for a while. Called TAC (GM technical assistance) and they never heard of such a thing. After some digging, we found that '12-13 trucks have an additional spring on the pedal assembly. His truck didn't have enough force to return the pedal fully and after a while of driving was creating brake hat and a pulsation. After installing the spring, new rotors, and pads, all is good.
 

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