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Online Wrench
Online Wrench, ASE Certified Technician
Category: Car
Satisfied Customers: 402
Experience:  ASE Certified, Asian and Domestic Specialist
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I have a 1999Buick Ultra. It has approx. 120000 miles.

Resolved Question:

I have a 1999Buick Ultra. It has approx. 120000 miles. The front brakes were replaced the first time at approx. 40000 miles. Since that time yhe brakes have been replaced three times the rotors have been replaced and the rotors have been turned several times. about every 10000 miles the front end starts shimmying when the brakes are applied. The dealer keeps telling me the rotors are warped and after turning them it is O.K. for another 8-10000 miles. Is there a way to fix this? could it be in the ABS system?   Thank You.   Bob Duncan
Submitted: 8 years ago.
Category: Car
Expert:  Online Wrench replied 8 years ago.
Hello and Welcome to! There are a few reasons why the rotors are prematurely warping. The first reason is over toqueing the lug nuts. Make sure that whoever is installing the lug nuts is using a torque stick or torque wrench to tighten the nuts. Also, make sure that the rotor mounting surface are free of heavy rust build up and corosion. You will also need to make sure that the brakes are not dragging. This will cause excessive heat and warpage. Lastly, make sure that a quality brake rotor was installed. Cheap rotors willl often warp faster than a good brand. If you have any questions please feel free to ask. I will be glad tohelp in any way that I can. If this information was helpful, please click ACCEPT! Thank You.
Customer: replied 8 years ago.


Sorry, but this answer does not help. This work is being done by a GM dealer, using standard practices and the rotors were replaced with GM parts.

All of your suggestions are good, however they do not solve the problem. Any other ideas?

Expert:  Online Wrench replied 8 years ago.
Ok. Well if these were all performed correctly, then you need to have the rotors turned with an on-car lathe. An on car lathe turns the rotor true to how it is mounted on the car not true to how it sets on a bench lathe. This is the only way to get the rotors completely true. I have fixed problems like yours many times by turning with an on-car lathe. I would highly recommend you do this. Also, I still do not think it is a bad idea to check with them to make sure they were doing these correctly. I understand they are a Gm dealer, but I've seen some pretty dumb "gm dealer techs". Just a thought. Let me know how it goes. I will be glad to provide further assistance if needed. Thank You.
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