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2009 CTS AWD DI 2014 AWD CTS DI
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639 Posts
Discussion Starter #1
OK, this is a followup to a previous problem involving the brakes on my 02 DHS. At about 90K I had the front brakes replaced on the car and stupidly did not replace the rotors which seemed fine. The back brakes were left alone with about 12% life left.
Around home driving slower things seemed fine but then we went on a trip and I found the need to brake hard on an interstate traveling downhill at about 65MPH. I thought the whole front end was going to shake apart to the extent that my wife insisted we pull off an exit and find someone to check it out. I agreed since I thought with such a bad shake it might be a suspension problem. We were lucky enough to find a Caddy Dealer who said that the front end was fine. [someone had previously suggested that a knuckle might be the problem] They suggested cutting the front rotors and putting new rotors and pads on the rear which I did. The car did brake much better after the repair and we continued on our trip.
It is now a couple thousand miles later and I am expriencing enough of a shuddering problem in the front when braking that it will need to go back to my shop. [If it starts to shudder when braking at speed and I release my foot from the brake and quickly reapply I can get it to settle down} I am prepared to put new rotors on the front but here are my questions.
1. I have read that struts could cause [or contribute to] this problem and that their useful life is about 80K. I have 104K. Is there a way to gauge the need for replacement and could worn struts contribute to the problem? Could they be the sole cause for the shuddering?
2. Since the front ceramic pads have only a few thousand miles of use is it necessary to replace them if I replace the cut rotors with new ones?
I appreciate any assistance and my wife really appreciates the help.
 

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'98 STS (RIP @ 206,xxx miles)
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Based on your description, I would suspect (1)your brake pads were not bedded properly and (2)there is a possiblity your wheel lug nuts have not been torqued to the recommended value in the correct sequence.

Cold (a relative term) rotors and brake pads can sometimes produce a little bit of vibration. Warming up the pads and rotors (with moderate braking effort) will usually result in silky smooth operation.

If your rotors are distorted as a result of improper wheel lug nut torque value/sequence, you can have them cut with a non-directional finish as long as the rotors are not beyond the minimum thickness dimension.

Then you bed the brake pads to the rotor with ten hard rolling stops from about 45 MPH to generate the heat required to transfer a microscopic layer of pad material to the rotor. Expect some smoke and aroma of burning glue. Allow the brakes to cool and repeat.

The last thing I would suspect is struts / shocks. Brakes and shakes tend to be an emotional issue; related to perceived safety concerns. If you can stop the car before hitting the police vehicle, your brakes are doing the job. Just not as smoothly as they could.
 

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2009 CTS AWD DI 2014 AWD CTS DI
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639 Posts
Discussion Starter #3
Thanks. What is the torque for the lug nuts. I am guessing somewhere around 95lbs??? Assuming the torque is OK [after all I was at a Caddy Dealer] should I just go out and do the rolling stops?
 

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'98 STS (RIP @ 206,xxx miles)
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4,854 Posts
Do not assume the nuts are torqued correctly (100 lb ft) just because it was done at the dealer's shop.

You have nothing to lose by doing the rolling stops. Put some heat into those parts and see if anything changes.
 

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2015 Mazda3 S GT Hatchback 2013 Kia Optima SXL
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I had the same issues with my '02 Seville. After a few times cutting stock rotors, I changed to drilled and slotted rotors (Ebay-R1Concepts). It completely fixed the issue. It seems that stock rotors just cannot stand the added heat that ceramic pads generate. The drilled and slotted rotrs disipate the heat much faster, and do not distort. You should either switch to a semi-metallic pad, or change the rotors if you want to use the ceramics.

Don
 
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