Brake judder
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Brake judder
I am trying to isolate a brake problem. The car is juddering when applying the brakes with any kind of force. I have a feeling the problem maybe in the wheels rather than the brakes - it seems to be predominantly in the left front but it's hard to tell. Anyone experienced similar problems or have any clues as to what the problem is? I have a ’91 Subaru legacy.
Thanks,
Ben.
Thanks,
Ben.
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Possible it could be the wheel (unbalanced), the tire (a damaged belt), the suspension bushings (worn out), or a loose suspension component.
If it is brakes (and it probably is):
DTV, the rotor needs to be turned because the surface run-out is excessive. DTV comes from pad material embedded on the rotor, uneven rotor wear, or a damaged pad.
If you have a micrometer measue the run-out of the rotor, you will need to find out the max run-out allowed. Or at minimum check the rotor thickness at mulitiple points around the rotor.
THE ROTOR IS NOT WARPED! IF YOU MECHANIC INSISTS IT IS, HUMOR HIM! BUT IT'S NOT WARPED
_____________________
My Technical Website on Brake Systems
If it is brakes (and it probably is):
DTV, the rotor needs to be turned because the surface run-out is excessive. DTV comes from pad material embedded on the rotor, uneven rotor wear, or a damaged pad.
If you have a micrometer measue the run-out of the rotor, you will need to find out the max run-out allowed. Or at minimum check the rotor thickness at mulitiple points around the rotor.
THE ROTOR IS NOT WARPED! IF YOU MECHANIC INSISTS IT IS, HUMOR HIM! BUT IT'S NOT WARPED
_____________________
My Technical Website on Brake Systems
Registered User
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Joined: Nov 2002
Posts: 1,644
From: Lawrence, Kansas
Car Info: 19' Impreza Sport Manual / 99 Miata / 13' OB
To see if it's a wheel, rotate your tires. The Judder will come from the back now if it was the front. If you can find a person to swap wheels with that's even better. My neighbor had this problem with his Outback. I put my spare wheels on just to see and it was still there. He took it quite a few places till he finally went to a Subaru dealer. It turned out to be excessive rotor run-out as stated above. One thing though. Subaru wants the rotors to be truned while on the car. Have a look here:
http://www.scoobymods.com/forums/sho...ighlight=brake
After they had this done the car was fine.
http://www.scoobymods.com/forums/sho...ighlight=brake
After they had this done the car was fine.
Registered User
iTrader: (2)
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Posts: 1,644
From: Lawrence, Kansas
Car Info: 19' Impreza Sport Manual / 99 Miata / 13' OB
>Except cars with inboard rotors, sorry old Alfas and old Jags!
And old Audi's, our 100LS had these, talk about brake fade...
And old Audi's, our 100LS had these, talk about brake fade...
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simple things first. check your tire pressure. one low tire will cause brake judder. had a slow leak in the passenger front that caused awful amount of juddering. felt like the rotor was warped badly. something to do with the fact that the low tire revolves at a slightly higher rpm.
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Joined: Nov 2002
Posts: 1,644
From: Lawrence, Kansas
Car Info: 19' Impreza Sport Manual / 99 Miata / 13' OB
Originally posted by weeble
simple things first. check your tire pressure. one low tire will cause brake judder. had a slow leak in the passenger front that caused awful amount of juddering. felt like the rotor was warped badly. something to do with the fact that the low tire revolves at a slightly higher rpm.
simple things first. check your tire pressure. one low tire will cause brake judder. had a slow leak in the passenger front that caused awful amount of juddering. felt like the rotor was warped badly. something to do with the fact that the low tire revolves at a slightly higher rpm.
Registered User
Joined: Dec 2002
Posts: 79
From: new milford, ct
Car Info: 02 silver impreza wrx
just so all you guys know, a rotor CAN warp. rotor warping is caused by high heat within the breaks that cant escape, or heavy breaking.
the heat caused by heavy breaking, or the rotor being undersized, can cause a rotor to warp, meaning, it deforms because it cant cool down fast enough, then when the brakes are released, the rotor cools down at high speed, and some metals cool quicker that others (there are more than one metal in a rotor), so as the rotor cools, one metal cools faster which means it shrinks. this pulls the other metal (the one that cools slower), and therefore WARPS the rotor.
i am a mechanic myself and bump into this problem every day. if your mechanic says the rotor is warped, he can be right, but first make sure that, if they want to replace the rotor, they have measured the rotor, and found it to be below spec.
rotors arent that expensive, and pretty easy to replace yourself with basic hand tools. but i do advise, if you are changing the rotors, do them in pairs, and put a fresh set of pads on too to make sure your rotors dont prematurely warp again.
the heat caused by heavy breaking, or the rotor being undersized, can cause a rotor to warp, meaning, it deforms because it cant cool down fast enough, then when the brakes are released, the rotor cools down at high speed, and some metals cool quicker that others (there are more than one metal in a rotor), so as the rotor cools, one metal cools faster which means it shrinks. this pulls the other metal (the one that cools slower), and therefore WARPS the rotor.
i am a mechanic myself and bump into this problem every day. if your mechanic says the rotor is warped, he can be right, but first make sure that, if they want to replace the rotor, they have measured the rotor, and found it to be below spec.
rotors arent that expensive, and pretty easy to replace yourself with basic hand tools. but i do advise, if you are changing the rotors, do them in pairs, and put a fresh set of pads on too to make sure your rotors dont prematurely warp again.
Registered User
Joined: Nov 2002
Posts: 110
From: Natick, Massachusetts
Car Info: 1999 Subaru Legacy GT Limited - Quick Silver Metallic
Originally posted by Peaty
Rotors can also warp if you torque down the lugs too tight too.
Rotors can also warp if you torque down the lugs too tight too.
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