Noticed at the beginning of my ride today that there was some fuid visible around the innards of my XTR trail back brake lever. Didn’t think too much of it as the bike hasn’t been cleaned for a few rides.
Anyhow, it started pulling back to the bars during the ride on an initial grab of the lever, but would harden up nicely on longer descents when on the brakes for a period of time. Until the lever jammed at fully pulled and stayed there. It released after a bit of faffing, but then kept jamming.
Once home, I’ve stripped it down, cleaned it (it was filthy inside) and reassembled, to no great success. The master piston is jamming at full lever travel, and it doesn’t seem to want to take fuid from the resevoir meaning the pads aren’t resetting. I’ve bled it back and forth a few times – I can push fluid from the caliper up, but I can’t from the lever down.
Any ideas? The seals on the master piston looked OK, although the lever end of the piston looked pretty scuffed up. I’m going to guess it is a seal though, but I don’t understand why it’s started sticking – it’s almost like one of the seals has swelled up.
Anyone know if the master piston is identical to a Deore one? Tempted to try buying a deore lever for £19 and swapping the innards over, athough there’s a risk that there might be some lever body scoring internally.
Thanks!