Brake Rub

Rockbottom

Active Member
Finished a ride this past weekend and noticed there was excessive brake rub on the rotor with the front tire. So at home I go through the usual check list to see what the problem is: make sure the wheel is properly trued, check that the rotor is not bent, Re-align the brake caliper, loosen the caliper bolts, squeeze the brake while re-tightening bolts. Nothing really works. I notice now that there is virtually no space between the brake pads and rotor. So I take the pads out and try to reset the pistons, but after a few squeezes on the brake with everything back together, the same issue persists. Anything else you recommend at this point?

Brakes are Magura MT7 (dual pistons)
 

pooriggy

Well-Known Member
Team MTBNJ Halter's
It sounds like the brake pistons are not retracting.
On my Shimano xt brakes, periodically I have to clean around pistons with rubbing alcohol. I remove wheel and squeeze brake lever to pull pistons out, clean them, then lightly lube piston sides with mineral oil on q-tip and push piston back in. This is recommended by Shimano.

I would see if you can find any info Magura recommends for cleaning pistons.
 

Magic

Formerly 1sh0t1b33r
Team MTBNJ Halter's
Did you recently get new pads or bleed/top off the brake fluid? Some after market pads may be thicker than OE pads, which I find with the Jagwire pads I started using. Additionally, if you bled the brakes or topped off the fluid with a quick bleed, you may have filled the extra space there used to be with extra fluid and the piston may not be retracting far enough.

Also, what Iggy said otherwise. I had to do the above on cross bike SRAM brakes. One piston was getting stuck. Never had issues with any of my XT brakes.
 
Last edited:

Rockbottom

Active Member
Think you may be right about the pistons getting stuck. When I removed the pads it seems the pistons on the right side were extended out slightly more than the left ones.

I’ll have to research the best way to remove and clean pistons for magura. I’m a bit nervous on removing and cleaning them myself.
 

pooriggy

Well-Known Member
Team MTBNJ Halter's
Think you may be right about the pistons getting stuck. When I removed the pads it seems the pistons on the right side were extended out slightly more than the left ones.

I’ll have to research the best way to remove and clean pistons for magura. I’m a bit nervous on removing and cleaning them myself.
Do not remove piston, this will put air in your brake lines.
Your piston is sticking, to free it up, clean it, push back in with tire lever and see is that works, it may take several attempts.
The piston could be bad as well, in which case Magura might replace.
 
Top Bottom