shimano brakes not returning

Have some XT M8020 brakes, the rear lever isn’t returning.

the diagnostics so far have included:

full bleed, but that didn’t help.

extend one piston at a time, clean and apply a light coat of mineral oil, retract and repeat with the other piston, several times.

squeeze lever and manually retract pistons and repeat to see if it loosened up the stuck bit.

none of which have helped.

leads me to conclude it’s the lever that’s not returning on it’s spring and the caliper is OK.

in the absense of being able to rebuild these, it’s new lever time?

sound about right?

I believe I had one go like this and it was the spring in the lever. Levers can be picked up cheap on ebay, so I just replaced it.
I’ve got a spare in the garage if you can’t find one.. hmm not sure if it’s front or rear. Shout if you want me to ave a look

The piston in the lever has a rubber face perfectly shaped to trap small particles of grit between it and the lever body, once this happens the lever is for the bin unfortunately.

Can’t you get a new spring etc? My mate bent the brake lever blade on my Code and for £17 or something like that I got a new lever blade / swing link / spring / bushes / washer.

The piston in the lever has a rubber face perfectly shaped to trap small particles of grit between it and the lever body, once this happens the lever is for the bin unfortunately.

^^^

At least economically…. I’ve pulled them apart for fun on a rainy day once replaced and got them working again but I’d need to value my time at 10p/hr to make it economical.

Just remove the lever and check in there, there’s not a lot in there, you take off the rubber cover, loosen the grub screw and then knock the silver pin out from the bottom, then the lever comes out, check over, clean, make sure the spring is fine, then reassemble, the spring is a proper fiddle to get in, if you have a punch that fits the hole well then put that up from the bottom to hold the lever and spring, then insert the pin from the top and push out the punch to make sure the pin goes in straight and without that spring coming loose!

then reassemble, the spring is a proper fiddle to get in, if you have a punch that fits the hole well then put that up from the bottom to hold the lever and spring, then insert the pin from the top and push out the punch to make sure the pin goes in straight and without that spring coming loose!

I’d love to see a vid or pics that… I’ve never managed a technique for reassembly that doesn’t involve a LOT of swearing and luck.

Yeah, first time i found never to use hex keys with rounded bottoms as the spring just doesn’t line up, it has to be a punch or something with the right diameter and flat to make sure you trap that spring, then the pin should just go in with a bit of persuasion, of course for this the lever has to be off the bars, it’s a definite 2 hander with extra fiddle, wishing you had a third hand to get that tool you always forget!

I has a spring go after a crash, I just used a rubber band to pull the lever back, worked fine, looked shit.

Sounds like a pain to sort. Will of course try once my replacement brake turns up. 🙂

Yes, the piston face is bevelled to ease assembly but is a perfect grit trap and once the grit is stuck in the soft body of the lever it isn’t coming out in a hurry.