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Discussion Starter #1
IHA 97 malibu 2.4L. I did the brakes earlier this year. No brainer there. However, over the last few months when braking the front shimmy's. It vibrates badly when braking at high speeds. At slow speeds when I brake it feels like they are grabbing and relaesing slightly. Are the rotors bad? I had the tires rotated recently and they said the brakes were good, however the place I took my car for the tire rotating is subject to less than honest opinons.

Ideas? Thanks!

Happy Holidays!
 

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Yes, your rotors are warped. If the vibration is heaviest when you first hit the pedal at highway speeds and then goes away as you slow or increase pedal pressure, that would indicate the rears, if the vibration gets worse as you slow, then it would indicate the front. Usually that happens from techs not using a torque wrench when changing the tires. You may be able to have the rotors turned, but the price of rotors has really come down the last couple years so it might be better to just buy new thick rotors rather then to turn them and have thin used rotors. If you buy new and replace yourself be sure to use a torqe wrench when putting the tires on and clean the new rotors as they have a protective film on them to keep from rusting in the box. If you don't clean them with a parts and brake cleaner they could glaze over and not work so good.
 

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Discussion Starter #3
The vibration is heavy when braking at freeway speed but then lessens as I slow. If I really stomp on the brakes the vibration is less. The rear brakes are drum. The front, obviously, are disk. So am I looking at replacing the drums in the rear or the rotors up front? I heard the 97 Malibu needs a press to put the rotors back on. Is that correct?

Thanks for your help!
 

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It sounds like the rear drums the way you described it.
There are no press on rotors, it may be stuck on and appear to be pressed on and you may need a BFH to beat the rotor off the hub, but they are not pressed on.
 

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If the Steering Wheel shakes, Its the Front Discs. They are more likely to get warped than drums. Since they do most of the stopping. And have the greatest amount force applied to them.
 

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Discussion Starter #6 (Edited)
Front or rear? That is the question. Let me see if I can give a better recap of what is happening; when at freeway speeds, when the brake is applied, the steering wheel vibrates badly then subsided some as I slow or if the brakes are applied hard at a quick stop. When traveling at slower speeds, it feels like the brakes are grabbing and then releasing briefly as I come to a stop. Either way the steering wheel feels like it is puliing to the left and right while that is happening. There is a rubbing round coming from what sounds like the front as I stop. Not a grating sound becasue the front pads and rear shoes are realativly new.
 

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Get a pair of new front rotors. Relatively inexpensive and easy to swap. As others said, USE a torque wrench to get the lug nuts on evenly. Make sure to clean and relube the caliper mounts/slides for even operation. It's relatively rare for drums to get warped on these lightweight cars...

Locally new rotors are about the same price as having old ones turned, if there is even enough metal left to do a proper job. Labor is the same so why not have new brakes?
 

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Discussion Starter #8
OK. I'll go with the front rotors. Do I need to replace the pads as well? If the rotors were warped, would they have not worn the pads unevenly?
 

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That's a judgment call to make when you take it apart. If the pads are 50% or more material left I'd run um. If less then that replace. Be sure to grab a can of parts and brake cleaner for those new rotors.
 

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caused by cheap material in the rotor. GM will tell you its caused by people not using a torque wrench on the wheels, they dont ever want to admit there own mistakes.

no offense to anyone, but a torque stick will get the torque where it needs to be. its limited to a set spec, yeah it wont be exact like a torque wrench, but it will be close.
i can see if its like 90 ft lbs on one nut then 130 ft lbs on another, but thats pretty inconsistant. im sorry but i just dont believe in the whole "oh its caused by people using torque sticks" gig. hey if you want to use a torque wrench on everything, go for it, i like to eat during the week and not take 15 minutes to a tighten wheel on every car that comes in the door.
 

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Uh the proper thing to do is torque the wheels to specs, they recommend it for a reason. an improperly torqued fastener can either strech it beyond it's holding ability or if it's not enough cause it to loosen up. Torque sticks suck and are not even close to being acurate. I'd put a torque wrench to any wheel I've taken off and put back on, I surely wouldn't want a wheel to come flying off a car and be liable for the damages.
 

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caused by cheap material in the rotor. GM will tell you its caused by people not using a torque wrench on the wheels, they dont ever want to admit there own mistakes.

no offense to anyone, but a torque stick will get the torque where it needs to be. its limited to a set spec, yeah it wont be exact like a torque wrench, but it will be close.
i can see if its like 90 ft lbs on one nut then 130 ft lbs on another, but thats pretty inconsistant. im sorry but i just dont believe in the whole "oh its caused by people using torque sticks" gig. hey if you want to use a torque wrench on everything, go for it, i like to eat during the week and not take 15 minutes to a tighten wheel on every car that comes in the door.
Being ASE certified then you must know that the ASE no longer recognizes torque sticks as an accepted alternative to a torque wrench. There are two reasons for that. One is metal fatique from the constant flexing. The other has to do with the wide variety of impact wrenches and the degrees of turn in each stroke. If you had one that was limited to say 1 degree, then you could expect quite uniform tightness, but if you have one that is like 15 degrees, there is likely a wide range of torque. Not exactly on the numbers, but you should get the idea.
 

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Uh the proper thing to do is torque the wheels to specs, they recommend it for a reason. an improperly torqued fastener can either strech it beyond it's holding ability or if it's not enough cause it to loosen up. Torque sticks suck and are not even close to being acurate. I'd put a torque wrench to any wheel I've taken off and put back on, I surely wouldn't want a wheel to come flying off a car and be liable for the damages.
Had it happen. Coasting from 90 for an upcoming stop sign. About 65 when the rear wheel passed me. Thank God no cross traffic at the intersection. What a ride!
 

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My Maxx is doing the high speed shimmy too. I will try replacing the front rotors. Thanks for the info fellas
Is that only when you step on the brakes ??
If not, it probably is an entirely DIFFERENT problem.

It could be the rears too.......or only one rotor.

It would be better to first find out where the problem really IS before changing out parts.

If it is the rotors, they often can be "turned" cheaper than replacement.
 

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First thing, there is no such thing as warped rotors. Pulsing/shimmy can be caused by a lot of things. Uneven brake pad deposits on the rotor, rust spots on the rotor (check the back side of the rotor), lateral thickness variation, excessive wheel bearing run out or excessive run out on new or used rotors. Throwing parts at a problem is a good way to spend ten times what it would cost to inspect and analyze the brakes to find out what is causing the shimmy. Uneven brake pad deposits may be taken care of by going out and doing about 20 hard stops from 25 mph to 5 mph without locking up the wheels.

Bill
 

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First thing, there is no such thing as warped rotors. Pulsing/shimmy can be caused by a lot of things. Uneven brake pad deposits on the rotor, rust spots on the rotor (check the back side of the rotor), lateral thickness variation, excessive wheel bearing run out or excessive run out on new or used rotors. Throwing parts at a problem is a good way to spend ten times what it would cost to inspect and analyze the brakes to find out what is causing the shimmy. Uneven brake pad deposits may be taken care of by going out and doing about 20 hard stops from 25 mph to 5 mph without locking up the wheels.

Bill
It's ignorant to say rotors never or can't warp. I see it all the time. I would call lateral thickness variation warping. And the cure is to replace or turn the rotors.
Excess wheel bearing run out will cause a low brake pedal, not a shimmy, and I've never seen any kind of pad deposits on a rotor. Just saying...
 

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Sounds like someone is a paid mechanic....lol I replaced the rotors yesterday, no more shimmy. I purchased the high end rotors and they where obviously higher quality than GM put on stock. While I was at it, I had the old ones checked out by a friend of mine...they where warped, severely. So yes they can warp, no "Special mechanic inspection for $$$$" needed.
 

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they where warped, severely. So yes they can warp, no "Special mechanic inspection for $$$$" needed.
The rears can warp too.
There is nothing special about jacking up the car, spinning the wheels and applying the brake lightly to see which one is actually causing the problem.
If you did not do that, then you just got lucky.
 

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First thing, there is no such thing as warped rotors. Pulsing/shimmy can be caused by a lot of things. Uneven brake pad deposits on the rotor, rust spots on the rotor (check the back side of the rotor), lateral thickness variation, excessive wheel bearing run out or excessive run out on new or used rotors. Throwing parts at a problem is a good way to spend ten times what it would cost to inspect and analyze the brakes to find out what is causing the shimmy. Uneven brake pad deposits may be taken care of by going out and doing about 20 hard stops from 25 mph to 5 mph without locking up the wheels.

Bill
It's ignorant to say rotors never or can't warp. I see it all the time. I would call lateral thickness variation warping. And the cure is to replace or turn the rotors.
Excess wheel bearing run out will cause a low brake pedal, not a shimmy, and I've never seen any kind of pad deposits on a rotor. Just saying...
Sounds like someone is a paid mechanic....lol I replaced the rotors yesterday, no more shimmy. I purchased the high end rotors and they where obviously higher quality than GM put on stock. While I was at it, I had the old ones checked out by a friend of mine...they where warped, severely. So yes they can warp, no "Special mechanic inspection for $$$$" needed.
The rears can warp too.
There is nothing special about jacking up the car, spinning the wheels and applying the brake lightly to see which one is actually causing the problem.
If you did not do that, then you just got lucky.
Guys, let's all be civil, especially you, Rukee.

Brake discs DON'T warp!

That link above is to a site that has more knowledge than anyone on this forum (to the best of my knowledge) about brakes. And Bill was absolutely correct when he said that rotors don't warp. (Disclaimer: Read the article. At the top it says they can, but only if installed incorrectly, not due to braking.)

If you have a real desire to learn and understand how things actually work it will make sense and you'll be miles ahead of all the others who say the oft-repeated phrase, "the rotors are warped".

If you want to comment, take the time to educate yourself, and take the time to show some respect to others who share truth with you. Bill did just that and his reward was a comment inferring he was ignorant.

If you click on my screen name and find other posts I've made you'll see that I'm not always right. The difference between me and some others is that I can admit when the information shared with me is a better understanding than I had coming in, and I leave with a better understanding. How can any of that be bad?

If you choose to stay in the stone age, go ahead, but please don't start spouting opinions that you haven't researched or for which you have only partial knowledge.
 
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