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Old 03-13-10, 05:21 PM   #1
PMK
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Brake Disc Resurfacing

Our rear brake disc has been becoming more and more burnished smooth over time from use. While it still stops ok, it's just not as crisp as when new.

The braking surface on the disc has been burnished to be almost polished.

I did some work on the the rear brake last week, including giving the pads a good scrub and wash with Brakleen. This definitely perked up the pads, removing all the fine dist and residues. The disc too was wiped down using Brakleen.

While the brake was better today it was nothing spectacular.

So I was curious if anyone has a good method for adding some texture back into the disc. My initial thoughts are to run a DA sander across it a few times.

Any ideas or thoughts.

PK
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Old 03-13-10, 09:29 PM   #2
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If you've just cleaned the rotor and pads it will take a little time for the rotors to get back their bite, similar to the original bedding-in process.

Scuffing them up to remove the sheen -- by hand in a chris-cross / hash pattern or with some type of sander, dual action or otherwise -- will simply make it take longer to re-season the rotors, as mentioned above AND will chew up a little more of your brake pads in the re-bedding in process.

About the only time I'd do anything to my rotors would be if they became warped, nicked or deeply worn in the middle / concave after extensive use (easily checked with a steel straight edge). Of course at that point the fix is getting new ones.

There are some other things you can do if you find you're rotors and calipers are squealing or making other undesirable noises, but that doesn't seem to be your issue.
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Old 03-14-10, 12:55 PM   #3
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If I understand your concept correctly, you believe the pad/brake linings will remove the polished effect that has occurred to the disc.

PK
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Old 03-14-10, 01:28 PM   #4
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Quote:
Originally Posted by PMK View Post
If I understand your concept correctly, you believe the pad/brake linings will remove the polished effect that has occurred to the disc.
The burnishing / polishing on the rotor isn't typically anything to worry about. In fact, burnishing is part of the bedding-in process that occurs on all new rotors or larger automotive type rotors that can be machined to remove surface irregularities. However, until all of the pores in the rotor refill with brake pad material -- also part of the bedding in process -- the rotors and pads won't exhibit their full stopping power. If you sand or otherwise scuff up the rotor it will just take that much longer for the rotors to be re-burnished and bed-in.

Again, if the rotors braking surface has actually been worn down from use to the point where the cut-outs or drillings are doing a cheese grater thing to your pads or the centers have become concave, then it's probably time for a new rotor and pads. There are some things you can do to re-chamfer drilled cooling holes to extend rotor life, but that's about the extent of reworking rotors. On the bright side, if you shop around you'll find rotors aren't all that expensive to replace if you think it will improve your braking.
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Old 03-14-10, 02:29 PM   #5
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No the wear to the disc is not excessive in regards to thickness minimums.

The disc braking surface itself became highly polished from use. My guess is that road dust contaminated the pads and the rides when we got caught in the rain then contributed to the polished condition.

With everything currently clean, I'll see if a couple rides will reestablish a crisp brake.

PK

Last edited by PMK; 03-15-10 at 03:05 PM.
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Old 03-14-10, 09:35 PM   #6
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No chamfer on my holes and try sintered pads
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