how to stop rotor from rubbing brake pad?

[bitt3n]

I have a brand new Shimano rotor that rubs the pad ever so slightly at one point every revolution. That's the absolute best I can get it positioning the rotor between the calipers by eye. If I do the trick where you squeeze on the brake and then tighten the quick release to center the rotor in the pads, it rubs a lot more. The pads are really close together with maybe 0.1mm on either side, so it's not like the rotor's really out of true to any great degree.

I read somewhere that to set the pad spacing you remove the pads, press the calipers back into the pistons with a plastic tire lever, put the pads back, then squeeze the brake with a plastic spacer between the pads. This has not solved the problem.

Is there some way to get the pads eased off slightly? The pad is just grazing the rotor, creating a rasping sound.

[echelon_john]

True the rotor. If you don't have a proper tool, use a crescent wrench cleaned REALLY well with alcohol prior to using. Be gentle; you don't need a lot of force.

[giordana93]

http://www.parktool.com/product/rotor-truing-fork-dt-2


[/URL]

[foo_fighter]

Rotor Zing is sometimes hard to avoid. Are these hydraulic brakes? If the wheels still spin well but only have an audible zing then it's probably not slowing you down much. You can try putting business cards on each side of the rotor and then clamping and cinching the bolts.

[bitpuddle]

Originally Posted by bitt3n

I have a brand new Shimano rotor that rubs the pad ever so slightly at one point every revolution. That's the absolute best I can get it positioning the rotor between the calipers by eye. If I do the trick where you squeeze on the brake and then tighten the quick release to center the rotor in the pads, it rubs a lot more.

First, I’d suggest you center the calipers, rather than try to put the wheel in slightly off-center. Get the wheel straight in the dropouts, loosen the caliper bolts, actuate the brake, tighten the caliper bolts. Then deal with the caliper trueness. It isn’t unusual for them to be slightly off, even brand new.

You might want to take the bike to a good mechanic and watch the process once.

[JWDR]

Originally Posted by bitpuddle

First, I’d suggest you center the calipers, rather than try to put the wheel in slightly off-center. Get the wheel straight in the dropouts, loosen the caliper bolts, actuate the brake, tighten the caliper bolts. Then deal with the caliper trueness. It isn’t unusual for them to be slightly off, even brand new.

You might want to take the bike to a good mechanic and watch the process once.

I didn't take his post as saying he moves the wheel around or it's not fully in the drop outs to center the rotor but rather moves the brake caliper around until the rotor looks centered. This technique seems to work better, for me, for my two sets of cable actuated brakes.

[bitt3n]

Originally Posted by foo_fighter

Rotor Zing is sometimes hard to avoid. Are these hydraulic brakes? If the wheels still spin well but only have an audible zing then it's probably not slowing you down much. You can try putting business cards on each side of the rotor and then clamping and cinching the bolts.

Yes they are hydraulic. They spin but even when adjusted to minimize the noise make a light scraping noise.

That business card trick actually solved the problem (at least for now). They don't rub at all anymore.

Originally Posted by JWDR

I didn't take his post as saying he moves the wheel around or it's not fully in the drop outs to center the rotor but rather moves the brake caliper around until the rotor looks centered. This technique seems to work better, for me, for my two sets of cable actuated brakes.

I've done both. Pressing down on the brake and then tightening the bolts of the caliper leaves it scraping a lot. Pushing the wheel ever so slightly in one direction before clamping down the quick release makes it scrape less but still a bit. The business cards seem to have set the calipers back far enough to stop the rub though.

Originally Posted by bitpuddle

First, I’d suggest you center the calipers, rather than try to put the wheel in slightly off-center. Get the wheel straight in the dropouts, loosen the caliper bolts, actuate the brake, tighten the caliper bolts. Then deal with the caliper trueness. It isn’t unusual for them to be slightly off, even brand new.

You might want to take the bike to a good mechanic and watch the process once.

I guess I'll ride it for a while and if the problem comes back I'll true the rotor, because it's ever so slightly out of true.

This guy seems to explain the truing process pretty well.