GT disk brake question

Craig380 · Post by **Craig380** » Sun May 31, 2009 9:28 am

I've just rebuilt the caliper on my 380, as the old rubbers etc were perished. It's working & stopping the bike fine.

With the front wheel in the air, the wheel spins freely. If I position the tyre valve at 10 or 2 o'clock, gravity will turn the wheel without any help from me.

My question is, when the wheel is spinning in the air, I can hear the pads rubbing very very slightly on the disk at one point. But it doesn't seem to slow the wheel down -- it doesn't stop spinning at the same point.

Even after a long fast ride, I can still grip the disk with a bare hand, it's warm but not hot. The brake lever does not pulse and the forks don't dip repeatedly, so the disk isn't badly warped.

Is the above pretty normal? Thanks for your advice ...

Post by **Suzsmokeyallan** » Sun May 31, 2009 9:40 am

Its possible the disk may have some minor surface irregularities from its age etc, but cutting or refacing S/S discs requires special equipment and the cost isnt exactly cheap.
As long as theres no pulsing or serious signs of a warpage/grooving to create an issue, it should be fine.

Coyote · Post by **Coyote** » Sun May 31, 2009 10:16 am

I agree. After properly bleeding the brakes, the pads are right at the disk surface. When you apply and release the brake, the caliper piston has no spring return so it doesn't move away. It just relaxes. It's perfectly normal the hear some 'scuffing' of the pads when spinning the wheel.
Only the world is perfectly flat.

Craig380 · Post by **Craig380** » Mon Jun 01, 2009 2:46 am

thanks for the input, chaps

Craig380 · Post by **Craig380** » Tue Sep 08, 2009 2:17 am

An update on this -- a caliper strip showed the groove that the piston seal fits into was full of crud.

A clean & rebuild with new seals and no rubbing problem

rngdng · Post by **rngdng** » Tue Sep 08, 2009 4:35 am

Craig380 wrote:An update on this -- a caliper strip showed the groove that the piston seal fits into was full of crud.

A clean & rebuild with new seals and no rubbing problem

Every one I've done was like that. Glad you got it fixed.

Lane