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2009 Silver G8 GT Sport
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100 Posts
Discussion Starter #1 (Edited)
Ive owned my 2009 GT for about two months now. I flew to Fort Worth, TX and drove it home (North Mississippi). On the drive home, I noticed the front left brakes were grinding. It only happened as the car was just rolling to a stop. I also noticed that it doesnt do it until the brakes reach temperature. The day after I bought it, I grabbed my bore scope and did a quick brake check to see what the pad wear was. There was plenty of meat left on the pads, so I didnt worry too much. The family and I drove the G8 to Ohio for the 4th of July to spend the holiday with family. A few times during the trip, the left front was grinding so loud, the it sounded like metal on metal. I actially assisted with the emergancy brakes a few times when it was really bad. I pulled the wheel off when I got home. To my surprise, the pads looked great with over 75% pad life left. The rotors are also in great shape. I cleaned everything up and put it back together and have continued driving it.

It is really getting on my nerves and I wan't to fix it. I have customers riding with me from time to time and I really dont want any strange looks from them.

I just finished tearing it all down again to do a closer inspection. I cannot find a single problem with the brakes.

Is this a common problem? I couldnt find anything when searching. The previous owner used ACDelco pads and rotors on the front when he did the brakes. I'm tempted to replace the pads, but dont want to just throw parts at the problem.
 

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790 Posts
Pads installed wrong? Outside to inside swapped or outsides both on one rotor and insides on another? The pins could need lubing too.
 

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2009 Silver G8 GT Sport
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100 Posts
Discussion Starter #4
Pins are lubed nicely and move freely. Pads are installed correctly also.
 

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Premium Member
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1,849 Posts
Sticky brake caliper? Both front brake calipers got sticky on my G8 and were replaced under the 3/36 warranty, a long long time ago. The noise could've been described as "grinding" I guess.
 

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2009 Silver G8 GT Sport
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100 Posts
Discussion Starter #6
I was able to compress each piston about 1/16 of an inch by hand, so it didn't seem "sticky". I'm going to go ahead and replace the pad wth a premium ceramic. Rockauto has them cheap enough. I'll report back after the swap is done.
 

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I thought I had bad brakes in another car, sounded just like that. I replaced both pads and rotors and it still sounded like they were grinding. Then I replaced my tires and the grinding sound/vibration went away completely. Turns out the front tires were so badly cupped and hard (harsh wx, rubber compound that just got hard instead of wearing away, and autox alignment) that it was the tires making all the noise.

So... get the tires rotated and see if it sounds the same.
 

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2009 Silver G8 GT Sport
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100 Posts
Discussion Starter #8
I saw a post you made in another thread when I was searching previously. I rotated them when I changed the oil two weeks ago. No change at all....

I also checked all ball joints and control arm bushings. Everything looks great. Nice and tight.
 

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Have Bar Will Travel
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716 Posts
Ive owned my 2009 GT for about two months now. I flew to Fort Worth, TX and drove it home (North Mississippi). On the drive home, I noticed the front left brakes were grinding. It only happened as the car was just rolling to a stop. I also noticed that it doesnt do it until the brakes reach temperature. The day after I bought it, I grabbed my bore scope and did a quick brake check to see what the pad wear was. There was plenty of meat left on the pads, so I didnt worry too much. The family and I drove the G8 to Ohio for the 4th of July to spend the holiday with family. A few times during the trip, the left front was grinding so loud, the it sounded like metal on metal. I actially assisted with the emergancy brakes a few times when it was really bad. I pulled the wheel off when I got home. To my surprise, the pads looked great with over 75% pad life left. The rotors are also in great shape. I cleaned everything up and put it back together and have continued driving it.

It is really getting on my nerves and I wan't to fix it. I have customers riding with me from time to time and I really dont want any strange looks from them.

I just finished tearing it all down again to do a closer inspection. I cannot find a single problem with the brakes.

Is this a common problem? I couldnt find anything when searching. The previous owner used ACDelco pads and rotors on the front when he did the brakes. I'm tempted to replace the pads, but dont want to just throw parts at the problem.
I saw a post you made in another thread when I was searching previously. I rotated them when I changed the oil two weeks ago. No change at all....

I also checked all ball joints and control arm bushings. Everything looks great. Nice and tight.
so first off welcome to the G8 - you will love it.

secondly - I'm just up the road from you so if it just gets too bad send me a note and we can meet up and I might can help you out.

thirdly - very very often people put in the pads jaming them in and screw up the sheet metal spring/shims that go inside the caliper bracket to hold the pads parallel and provided a smooth track to slide on.

thus the spring/shims get bent up - and can stick out and scrape the rotors - they are often soft so they don't really scratch the rotor - but they make a horrible noise.

another option oft over looked is if the car still has the factory dust shield - it can be bent etc and rub on the rotors. these ring like mad and will cause a good bit of heat there. heat that get's the pads warm and can make them smell . . . . .


so I'd actually start there - check the pad guides (that's the word I was thinking of) and then I'd check the dust shield. I've taken the shields off on my car and been without for years.
 

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2009 Silver G8 GT Sport
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100 Posts
Discussion Starter #10
so first off welcome to the G8 - you will love it.

secondly - I'm just up the road from you so if it just gets too bad send me a note and we can meet up and I might can help you out.
I love it so far. CAI, X-pipe, my own copy of the Solo axle backs, and a superchips tune. A beast of a family car. I averaged 31 mpg on the way over to Little Rock last weekend.

Thanks fo the offer. I'm sure we will meet up at some point. I have a preatty well stocked shop. Its a total mess right now since I'm redoing my electrical. I'm adding 220v (ive had 220, but now it will be permitted...lol), more lighting, more outlets). After I finish the rewire, I'll finally be abe to sheetrock and run my Air conditioning. Started on the rewire early this summer... didnt make it very far.... just far emough to make a big mess before it got hot enough to make me stop and wait till fall/winter to finish...lol. The older and fatter I get, the less I can take the Memphis heat.

thirdly - very very often people put in the pads jaming them in and screw up the sheet metal spring/shims that go inside the caliper bracket to hold the pads parallel and provided a smooth track to slide on.

thus the spring/shims get bent up - and can stick out and scrape the rotors - they are often soft so they don't really scratch the rotor - but they make a horrible noise.
Thats the first thing I checked when I tore the brakes down the first time to check them out. Everything was perfect. Hoping the new pads will remedy it. My wifes Acura TL did the same thing for almost a year. It just stopped one day. Never fugured out what was causing it. Almost like there was a small rock stamped into the pad material that finally wore away or something. :shrug:
 

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Premium Member
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4,475 Posts
If your going to attack this in small steps, why not reverse the pads from side to side. If its the pads causing the problem, then that grinding sound ought to change sides. Only a little of your time involved.
 

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2009 Silver G8 GT Sport
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100 Posts
Discussion Starter #12
If your going to attack this in small steps, why not reverse the pads from side to side. If its the pads causing the problem, then that grinding sound ought to change sides. Only a little of your time involved.
If I pull the damn wheel off again, new pads are going in....Period.
 

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2009 Silver G8 GT Sport
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100 Posts
Discussion Starter #14

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OGOC MEMBER
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320 Posts
If the pads are in correctly, sliders clean installed properly and lubed, and dust shield out of its own way. The only other thing I could think of is the other owner either installed cheap chinesium low carbon junk rotors, or installed some serious hard race pads.
I see you opted to put a new set of pads on, hopefully this works out for ya.
 

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I'm going to say pads are in wrong...When you pulled the pads off to check them did you pull off both sides at the same time or just one side at a time ???

One pad per side has a slight bevel to it. You can get away with installing both bevels on one caliper but you CANNOT get away with installing two straight cut pads on one caliper as that is the side that will lock up, especially when the pads heat up...one beveled pad per side has to go into each caliper in a way that matches the calipers beveled side...(hope I didn't lose you there on that last sentence...LOL !!!)

Take a look closely at the curved edge of the pads' backing plate and you will notice what I'm talking about.

EDIT: ADDED THIS PIC...notice the left side of each pad, the pad on the left has the bevel and it's very slight...



Hope this helps you...
 

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OGOC MEMBER
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Got 8? Even if the OP had his pads in the correct way. This post will be very helpful to others with pics showing the difference in pads.
I'm sure this will help other guys attempting to install pads and rotors in the future.
Certainly not like the 60's 70's and 80's cars .... GM pads could only go in one way.
Cheers
Eric
 

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Got 8? Even if the OP had his pads in the correct way. This post will be very helpful to others with pics showing the difference in pads.
I'm sure this will help other guys attempting to install pads and rotors in the future.
Certainly not like the 60's 70's and 80's cars .... GM pads could only go in one way.
Cheers
Eric

Thanks CG !!! I had to learn this lesson the hard way even after hearing about the inner/outer pad so I just wanted to CLEARLY pass on the info...:)
 

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2009 Silver G8 GT Sport
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100 Posts
Discussion Starter #19
I didnt know about the bevel, but there are an inner and outer pad on each side. I have the pad with the wear tab on the inside of the rotor (this is the way I was taught, and the way the pads were already). I tried swapping them to the outside of the rotor just for ****s and giggles, but they wouldnt fit due to the wear tab hitting the mount bracket. Also, with the way the rivits are put on the back of the pads, (different for inner and outer) they will only fit in the caliper one way. You would never get the caliper on if they were backwards.

EDIT= I like the Autozone Cmax pads. I just hate the price. Are there any other aftermarket brake companies that use that design. I usually orderr on Rockauto, but if a customer ( I do TONS of side work at the house) shows up last minute and I dont have time to order, I'll run to vatozone and get the Cmax. I prefer them over the Wagner that Napa sells.
 

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I'd Rather Be Shifting
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564 Posts
Another vote to ensure the dust shield and pad clips are seated correctly. Even if it appears to be far enough away during a visual inspection, the metal will expand when heated allowing things to start touching/scraping. I went through this same experience with my TrailBlazer several years ago. It drove be CRAZY, but I finally pinpointed it to the pad clips (what the pads slide fore/aft on in the caliper). I trimmed them back with some side cutters and all was well.

FWIW, I am very pleased with my Hawk HPS pads on the front. I added those with new ACDelco rotors (running ACDelco rotors/pads in the rear). Just something to keep in mind when shopping pads.
 
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