98 brake problems HELP?
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98 brake problems HELP?
I have recently developed a shimmy in the brakes. I have decided it in the rear becuase when im driving and i pull the e brake it doesn't shimmy. Hince its in the front. I have taken it to 3 differn't dealerrs and they all say the same thing. THey look fine. But the shimmy still exsites. I have looked at them myself and the only thing i found was that they are a little over heated but not by much. the roter where turned to the minimuns the last time they were replaced which was only 5000 miles ago. I can figure anything else out. Any help would be great. The pads are new.
Last edited by twintips_16; Jul 7, 2006 at 11:22 AM.
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From: The LBC (Long Beach, CA)
If you have rear discs, the e-brake operates a drum within the rear disc...not the disc itself.
But these types of problems are typically limited to the front brakes anyways.
It could be a number of things.
Here are two possibilities, perhaps others will chime in also:
1) If you have checked for excessive runout (warpage) and found none, the you could have an uneven transfer layer of pad material.
Very lightly sanding the rotor surface to remove the old transfer layer, then bedding the pads again to establish a new transfer layer, may help.
2) you mentioned that your rotors were turned to their minimums. This is why I rarely if ever turn my rotors: turning them removes mass, which makes them less able to absorb heat and more prone to warping. So despite the fact that you had them turned, they could very well be warped again.
On my Expy, I turned the factory rotors once. I think it was around 40K miles, can't recall it was a long time ago. At any rate, had the shudder, measured a bit of excessive runout, so I turned them. Pretty much to the minumum recommended thickness, since they had a few miles on them.
The shimmy came back within a week. The rotors were warped again!
Ever since, I've run aftermarket rotors to good effect. Never got any warpage, but I had to replace a few rotors due to other problems (stuck caliper, etc.). But I don't turn rotors unless they need them...but I had a set of AP and StopTech rotors and both MFRs specifically recommended to NOT turn these rotors.
But these types of problems are typically limited to the front brakes anyways.
It could be a number of things.
Here are two possibilities, perhaps others will chime in also:
1) If you have checked for excessive runout (warpage) and found none, the you could have an uneven transfer layer of pad material.
Very lightly sanding the rotor surface to remove the old transfer layer, then bedding the pads again to establish a new transfer layer, may help.
2) you mentioned that your rotors were turned to their minimums. This is why I rarely if ever turn my rotors: turning them removes mass, which makes them less able to absorb heat and more prone to warping. So despite the fact that you had them turned, they could very well be warped again.
On my Expy, I turned the factory rotors once. I think it was around 40K miles, can't recall it was a long time ago. At any rate, had the shudder, measured a bit of excessive runout, so I turned them. Pretty much to the minumum recommended thickness, since they had a few miles on them.
The shimmy came back within a week. The rotors were warped again!
Ever since, I've run aftermarket rotors to good effect. Never got any warpage, but I had to replace a few rotors due to other problems (stuck caliper, etc.). But I don't turn rotors unless they need them...but I had a set of AP and StopTech rotors and both MFRs specifically recommended to NOT turn these rotors.
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Joined: Jan 2004
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From: San Diego, CA
Your shimmy sounds like a warped front rotor, if it's the brakes. You haven't mentioned any mods. It could be a bad alignment or wheel balance.
To determine if it's in the brakes test the shimmy while you're braking. If it gets worse it's the brakes. If not it could be a worn steering joint, bad wheel balance or alignment.
If the shimmy gets worse than it's the brakes. To determine if it's the front or rear feel where it's coming from. If you feel it most in the steering wheel then it's the front. If you feel it in the seat of your pants it's the rear.
If it gets worse when you brake then you have a warped rotor. If not, you're on your own for the rest. Good Luck!
Hope this helps.
To determine if it's in the brakes test the shimmy while you're braking. If it gets worse it's the brakes. If not it could be a worn steering joint, bad wheel balance or alignment.
If the shimmy gets worse than it's the brakes. To determine if it's the front or rear feel where it's coming from. If you feel it most in the steering wheel then it's the front. If you feel it in the seat of your pants it's the rear.
If it gets worse when you brake then you have a warped rotor. If not, you're on your own for the rest. Good Luck!
Hope this helps.