SRAM XO Trail brakes, rear caliper is stuck on.

Slowman

Likes Dirt
My SRAM XO Trail brake, rear caliper is stuck on.The pads are also worn down to a couple of microns thick.

I am thinking perhaps the pistons are simply extending too far and won't retract properly. I tried opening the bleed port and gave the lever a squeeze to remove any excess oil. I prized the pads apart and the wheel was spinning freely. I then reapplied the brake and the pads did not retract again.

I have new pads on the way but does anyone know if this happens when the pads are too thin?
 

link1896

Mr Greenfield
SRAM has issues with pad return at the best of times. There are three springs in the system, a spring spreading the pads at the caliper, a spring returning the master piston in the lever back to home position, and the spring returning the lever blade back out.

The caliper pistons are phenolic, XO trail are the same calipers as gen1 Guides.

Most common issue will be the pistons are gummed up in the calipers. Pull caliper off the bike, remove pads, with pistons still hanging out, clean them as best you can with a toothbrush and isopropyl alcohol.


Sram have flip flopped around with advice that pistons should be dry or lubed. Half of mine I’ve rebuilt with dot stable grease, other half are dry. No clear winners.
 
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