Disc Pad Rub; Tallboy, Elixir 5 and King Hub
I have a SC Tallboy with Elixir 5 brakes and Stan's wheels (ZTR hubs and Flow rims). Everything worked fine. Then I toasted the rear hub. I replaced the hub with a King hub; new spokes and reused the rim.
Now I notice the rear disc pads rub on the rotor. It's fairly subtle; I can't hear any noise. But when I spin the wheel so it turns once with the brakes setup, it spins many, many times with the pads removed.
I've tried setting up the caliper per Avid's manual (loosen the caliper bolts, squeeze the lever then tighten the bolts). Didn't help. I opened up the caliper, cleaned everything and bled the brakes. This didn't help.
One thing I did notice is that with the caliper bolts loose, the wheel spins fine. As I tighten down the caliper bolts, the wheel slows down.
While this is probably helping me get a better workout, I need all the help I can get keeping up with friends. Any idea what I'm missing or doing wrong? What should I try next?
Well, what's likely happening is that when you're tightening down the hardware, it's creeping back into the previous position you had with your other hubs, probably due to the paint and impressions the hardware has made from your last setup. Hub spacings for disc mounts are never 100% the same. The "real" fix would be to face those surfaces with special tools that your LBS might have but in the mean time you can very carefully press the caliper the other way while you're slowly and gradually tightening down both bolts. It's definitely a finesse thing and a white sheet of paper and a cold beer will help.
This would not likely help. The TB uses IS Rear mounts, and thus unless the OP changed/moved or removed the caliper bracket, facing the tabs will likely be of little benefit, especially if OP has a carbon frame.
Originally Posted by joeyjoedotorg
What OP has identified is the inadequacy of the "Avid Method" for setting up brakes. To start, you need to make sure that the pistons are completely free-moving, and that neither of them stick even the slightest bit. From there, you need to make sure that they both move evenly and simultaneously. Then, take the "CPS Stack" of washers and throw them away, and replace them with fixed, flat washers of the same height.
To properly set up a brake caliper, follow the Hope method. It works for ANY hydraulic disc brake. There are several vid's posted on the Hope website as well as on YouTube.
The other piece to this puzzle is the tension on the rear QR. If its not IDENTICAL each and every time you open/close the QR, your brake calipers will be misaligned. The solution to this issue is (since you now have a CK hub) swap to a 10x135mm Thru Bolt. Hadley sells a nice one and it works great with CK hubs and SC frames (I have one on my Blur).
Alcohol may lead nowhere, but it sure is the scenic route!
Thanks for the advice guys.
So armed with this new knowledge, I headed down to my bike shop basement last night. When I first got the King hub I put new pads in the calipers. I couldn't get the rotor to fit. Very frustrating. That's when I learned how to rebuild the caliper. I know the caliper was clean and free moving.
I decided to take all the advice above. Not having any flat washers available, I reused the CPS Stack but greased every contact point where the washers touched. I started with Avid's method of holding the brake and tightening the bolts. From there, I set it up visually by loosening one bolt, moving the caliper till it look centered, then tightening the bolt. I repeated with the other bolt.
And that's what it needed. Now the wheel spins freely. Thanks again for the help. I'm looking forward to trying it out on the trail today (other than the fact it's 24 degrees right now).