Cleaning Up a Brake Rotor
08-07-2007, 05:41 PM
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Cleaning Up a Brake Rotor
Is there a minimum amount of thickness you must take off when machining a rotor?
I ran into this question when I took an almost-new used rotor (which assume for the moment is perfectly true and straight) and asked the shop to "clean it up" the surface to help bed-in new pads. I thought they could just do a light cross-hatch on the surface and was surprised when they refused to touch it at all because it would "go below spec". The guy seemed to be was saying he would have to take a full mm off each side, and subtracting two mms from the almost-new current dimension would put it close to or just below spec.
Figured someone here would know the real ins and outs of this. Maybe two mms is a "rule of thumb" they are given? Maybe the operators at that shop have a heavy touch and aren't attentive or skilled enough to take off the minimum necessary amount of metal? Would a different/better place would be able to just "clean them up" and stay well above spec.
Comments?
I ran into this question when I took an almost-new used rotor (which assume for the moment is perfectly true and straight) and asked the shop to "clean it up" the surface to help bed-in new pads. I thought they could just do a light cross-hatch on the surface and was surprised when they refused to touch it at all because it would "go below spec". The guy seemed to be was saying he would have to take a full mm off each side, and subtracting two mms from the almost-new current dimension would put it close to or just below spec.
Figured someone here would know the real ins and outs of this. Maybe two mms is a "rule of thumb" they are given? Maybe the operators at that shop have a heavy touch and aren't attentive or skilled enough to take off the minimum necessary amount of metal? Would a different/better place would be able to just "clean them up" and stay well above spec.
Comments?
08-07-2007, 06:11 PM
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Drifting
Most machine shops don't want to touch brake rotors anymore. They don't want to be responsible if it goes below spec. How much you take off varies on each and every rotor. There is no golden rule other then you need to machine it until you have a machined surface.
08-07-2007, 06:49 PM
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They do not want to start turning one get one side nice then have the other not cleanup within the spec because they wasted their time since few people will want to pay for a useless rotor and they really do not want the liability of an indersized rotor so they do not want to give it back to you ...You can take a disc sander with medium grit and lightly crosshatch the surface then take a bit of time to bed in the pads they will conform to the disc surface after several hard stops. Not ideal but doable.