On my ride today I noticed after 20 miles that both brakes felt really pumped. When I stopped the back wheel wouldn’t rotate.

I took the wheel and pads off and pushed the pistons back in but it didn’t make a difference. I noticed that the lever was sucked in.

In the end due to lack of tools I had to let some fluid out by the lever and now the levers are against the bar. When I push the levers out they go back against the bar.

I’d say they are about 3 or 4 years old and have done 1000s of miles.

Can they be salvaged or has something inside gone pop which is not a serviceable part?

It was about 30 degrees on my ride today so is it possible I’ve just cooked them?

I’m happy to replace them as they have been flawless but if I can repair them even better. My only worry is that even if I rebleed them it might do it again.

I think they are Shimano bl m785b levers

If they are beyond repair is it worth buying new levers and using the old calipers or just go for a new set?

I have a new xt 11 speed I spec b (I think) will this fit new levers or will I need to go for older brakes?

Thanks for your help.

Yep, needs new seal, which they don’t do. In my experience, this would indicate that your brakes are 2 years and 1 month old so out of warranty. At 3 or 4 years, you got a good run out of those.

Brake (sic) out the credit card. If you want something serviceable rather than disposable, try Hope.

They are definitely out of warranty. Lol

Yeah they’re goosed. You can buy new levers easily enough – SLX won’t have the bite point screw that a) doesn’t effect the bite point of the brake in any way whatsoever b) either causes or at least makes it more likely the deal will fail depending who you ask.

Whether it’s worth it is up to you, they’re not usually much more money to buy complete and you get a set of pads too.

Your direct mount shifter won’t fit and you can’t modify them to fit.

You can fix this by stripping and cleaning the lever and piston. It is a total pain though.

Tried that a few times buy couldn’t get to the master cylinder piston seal by any non destructive method. I’d love to know how if anyone has but it seems once that piston seal has swollen/degraded, it’s game over.

I have had my XTR rh lever warranted twice. With my towbar mounted bike rack, the lever innards face into the slipstream; there are no seals to stop crap being blown in, I wonder if this could be the cause?

Master cylinder is pretty straightforward to remove.

Spill the beans then. Last one I tried to work on seemed to be peened over to seal the piston in.

Just a note, but XTR stuff has a 3 year warranty in the UK. I find it often worth the extra cash simply for the extra warranty…

Worth bearing in mind when you’re replacing.

(ps: I’ve also warranty returned a set of XTR brakes at < 12 months old)

OK, so I took the brakes off the bike and stripped and cleaned them. Eventually after a long soak, some tlc and some degreaser I got them to stop sucking and spring back.

I’ve now bled them and put the back on the bike. They feel better than before.

My worry now is that I’m kidding myself and at some point soon they are going to let me down.

Anyone had experience of this and fixed them. Did they last? Did they fail?

Do I just sell them as spares and repairs?

Thanks

It looks like you’ve just dismantled the reservoir so this is unlikely to fix your problem. I’ve fixed the problem you describe on a couple of XT M785 brakes. It happens when the plastic piston slightly swells and becomes lodged in the master cylinder. The piston can be fairly well jammed in there and take quite a bit force to remove. Follow this guide and it should fix them:

https://www.bikehub.co.za/forum/topic/155987-fixworkaround-shimano-xt-m785-brake-lever/

It’s fairly easy to do if you have a spare hour or so.

It’s really easy, remove the lever from the bike and disconnect the hose. Uncover the Allen screw(behind small rubber cover) that holds the lever blade pivot in place, remove it then push the pivot out. The lever comes off. And you can then push the piston out the body from the cable side to the lever blade. Dirt can easily get righting behind the piston under the lever and this seems to scratch the plastic piston body causing the piston to get sticky, cleaning and smoothing solve my issues and they were fine for ages after. The only fiddly bit is getting the servowave mechanism in and out.

My worry now is that I’m kidding myself and at some point soon they are going to let me down.

This, 100%, they will let you down when you’re either
a. on a steep, narrow descent
or
b. on a trip miles from civilisation

Anyone had experience of this and fixed them.

Yes, had piston out and freed it up a bit. Felt better temporarily.

Did they last?

No. A couple of decent rides maybe, that’s all.

Did they fail?

Yes. Pulled to the bar on a set of steep Calderdale steps.

Warranty, all three sets. Sold the replacements. Bought Hope E4s for all bikes. No regrets.