Disc brakes rubbing

[Still Rolling]

I have a set of XTR disc brakes that were new last July. Overall great, but on the last two rides the rear brake has started rubbing on the rotor. I have taken the pads out and depressed the two pistons to relieve the pressure. But after a few stops the rubbing returns. Any advice from those less technically challenged than I am.

[Quo Fan]

I sth rubbing constant, or is it only in a few spots. It could be that your rotors are warped, which happens to rotors when they get hot. If the rotor is warped, use an adjustable wrench and "tweak" the rotor back to true.

I don't have mych experience with XTR disc brakes, I use Hayes myself, but if you can re-center the caliper to the rotor, that may be your problem also.

[Ben-O]

Could your wheel be either bent or loose? Recently, my pads were rubbing due to a wobbly wheel.

At least with Avid and Hayes, there's a way to recenter the caliper, as I've just recently learned. There are screws that allow the caliper to move around. Loosen these, and with the brakes clamped down, tighten them up.

[Ben-O]

And one more thing, if the brake pads are just too close, they'll start rubbing. To space them out, there are these little plastic wedges you can push between the pads. Just ask your LBS.

[Still Rolling]

Here's an update:

Aided by Quo Fan's suggestion, I inspected my brakes closely and checked out Shimano's installation instructions. They have spacers to fine tune the postioning of the caliper relative to the frame (and relative to the rotor). A couple of extra spacers did the trick. Thanks.

[stich]

Problem is unless you buy the XTR brakes OEM then those spacers don't come with the brakes on the bike you bought from the LBS.

LBS mechanics suck in these parts too.

No attention to details what so ever, all of them.

Stich

[BadDNA]

I was having the same issue with my front rotor. I took it to my LBS and they replaced the shims for free. Took them about 5 minutes and they were glad to do it for me.

[Baconman]

Still Rolling - you cured the symptom but not the disease. I have 2 bikes with XTR discs and have had the same problem. What happens is one of the two opposing pistons in the caliper gets gunk on it and will stick when it's retracting. The reshim you did has aligned the caliper with its new center but what you really want is for the pistons to both retract evenly. To do this remove the wheel and brake pads. Then squeeze the brake lever while restraining the left pad. The right piston should move to the end of its travel. Clean the exposed piston. Repeat for the other side. I've found that squeezing the pads together and blowing compressed air behind the pads helps keep it clean back there.

[truckboy]

Bacon Man!

I like the name. Had to comment. I'll be watching for an interesting avatar.

[Ben-O]

Bacon Man!

I like the name. Had to comment. I'll be watching for an interesting avatar.


Mmmmmm.....Bacon...

http://www.homersays.org/simpsons/Homersays_00099.gif

[truckboy]

Yes, Lisa.... A magical animal.

[catbbq]

Bacon, pork chops, and ham? Wow.

but no ribs...

[NembaHobbit]

Badconman, I had the same problem with my XT's last year. Something to keep an eye on. Since I don't have a compressor, I clean the exposed pistons with a few q-tips.

Also Shimano hydraulics are supposed to be Self-centering. Others use the loosen & squeeze method mentioned above. If one side is dragging, try to wedge a business card between the tighter pad and the rotor. Hold it against the rotor, just behind the caliper and turn the wheel forward a bit. The card should get sucked in between. Squeeze and hold the lever firmly several times with the card in place and then remove. The pads should be more centered, repeat as needed. A blade-style spark plug feeler gauge is even better if you have one.

[NembaHobbit]

For those of us who are tool fanatics and perfectionists:

http://www.UtahMountainBiking.com/fix/diskrotortrue.htm

I stumbled across this cool site while researching an upcoming trip to Park City. Enjoy :-)

If you have a bunch of equally fanatical friends, maybe share the cost of the tools and have a big rotor truing party ;-)


Anne