Aaaaaaarghhh

OK I now feel better 🙂
Bear with me

I have 18 month old 975 XTR calipers
They used to be great but the dreaded sticky piston thing has slowly got to me
Currently the rear wears out the pad on one side when the other has 50-75% still good

Ive done the usual – cleaned them/lubed them regularly etc etc

They have finally got to me today

Ive stripped the bike down, pumped the pistons out, cleaned and lubed them with cotton buds but still it sticks
If I immobilise the ‘good’ pad I can even feel a ‘give’ or a crunch as the bad side overcomes whatever its sticking on

The only thing I havent done is change the piston seal
Im a bit daunted by this mainly as despite finding seals for every other make online I cant find any for Shimano
Is this an easy job anyway – Im assuming I just pop the piston out totally (which I havent yet done) and swap the seal

I know this is a common problem
Theres plenty of blubbering on MTBR about this but not really a definitive solution

I can see it affects XT as well and that sfb had a thread I remember before the old site was destroyed

So in conclusion, and thanks for your patience:)

1) What have I done wrong?

2) If cats Mark is lurking – HELP!!!!!

3) Will a Hope mini be anymore reliable and is there any reason I cant use it with XTR dual controls (which are lovely)

Ta – Happy Boxing Day
Enjoy your rides – these brakes have almost grounded me

If you can be arsed, try popping the pistons completely out and cleaning as much as you can get to. Obviously be prepared for the inevitable oil flood. It temporarily fixed mine, but I just ended up getting a cheap replacement calliper from ebay in the end 😳

Shimano don’t do service kits for their brakes…

Fellas

Many thanks, keep ’em coming

If I take out the piston completely is there a seal to be replaced or not?

And is the reason they dont do service kits that there are in fact no perishables like a seal for the piston?

Thanks

the reason they don’t do service kits is they don’t want you to take them apart, they want you to buy a new caliper

XTR has a 3 year warranty I believe, so try getting in touch with Madsion for a warranty replacement?

“Will a Hope mini be anymore reliable and is there any reason I cant use it with XTR dual controls (which are lovely)”

shimano use mineral oil, hope use DOT fluid. Cant mix the two systems as it will not work.

I have the same problem with m800 saints. Pop the pistons out and clean everything up. May work (didn’t for mine).

Hi guys – resurrected the thread as I have the same problem with my M975 brakes and a sticky piston. I have taken the pistons out, cleaned around etc. but do Shimano not make piston kits as above? £250 of brakes that cannot be repaired makes no sense to me at all!

Some seals are available – try madison.

Usually tho its a new caliper required

eeek. Will try madison and the cheaper seals first!!! As a thought – are all the pistons the same size across SLX \XT \ XTR???

I spent some time freeing up the pistons on one of my bikes the other day, I clamped one piston at a time and pumped the other out a few MM and cleaned the exposed bit with a strip of rag, lubed it with a few drops of Shimano mineral oil and then worked it in and out several times. They've been fine since.

Hi Glenn,

Try what Dibbs says. It can take a bit of patience, but I've never not been able to resurrect one yet! If you want any help, give me a shout.

Boris

Hi Boris!

I've mailed the guys at madison to see what they say, but today pumped the pistons out and cleaned them, cleaned the inner bits of the caliper and am ready to re-assemble them. One of the pistons (the one that works) has a couple of small marks on/in it so I'd prefer to replace it, but don't think the guys at Shimano make piston kits. Which is totally pants if that's the case!

I've got the same problem here with my xtr calipers. I didnt realise that xtr stuff had a 3 year warranty, so have just emailed madison. Will madison deal directly with customers, or do you have to go through a shop?

Bit of both MrH86! They prefer you to go through your LBS but will field queries, so I've tried them directly. To be fair, a product that sells for over £300 should have a bloody good warranty. Not to mention seal and piston kits! Suggest we both post what we're told here too!

Will do. Agreed. I was planning on replacing them with some hope brakes purely for the fact that they are easy to strip/rebuild and hope will sort any problems out asap. But, if I can get something sroted under warranty with shimano/madison then it will delay the purchase a bit.

Cool – was thinking the same thing! I've got XT servowave brakes on the spare bike so really wanted the parity between pads and bleed kit for both bikes to save the hassle. Hope I can sort this or it's Hope x 2 for the bikes. Here was me trying to save money . . . . ho ho.

I emailed madison a couple of days ago but got no reply. Decided to ring them up just now. If I return them to the reatiler I bought them from, they will send them back to madison and repair/replace. Turn around time about 5 days at the moment. lets see what actually happens.

What e-mail address did you use mrh86?

Just got my reply this afternoon! Said the same as above – take them back to the retailer where I bought them and they'll look at it and discuss with Madison. All happy days . . . . . .

BUT – Shimano still don't make aftermarket piston kits and the warranty is for 2 years. Seems odd when almost every brake manufacturer does make spare parts. Scary stuff . . . . .

By the time they fail the callipers have usualy droped in price, you can pick up the previous generation XTR/XT* for £15-£30 depending on where has them on sale.

For the time/hastle of replacing pistons/seals, thats not bad. Especialy as shimano stuff outlasts everyone else anyway. I've never had a calliper fail, (touch wood), but have destroyed hope and hayes brakes.

Shimano have never made rebuild kits for their brakes, but any* shimano calliper will work on any lever so you've got plenty of options.

* which bizzarely everyone still raves about after borrowing the bike

*I have no idea whether this still applies with servo wave.

I'd used sales@madison.co.uk BTW. Very helpful!

Update: went into my LBS (leisure lakes) who were very helpful, and more than happy to send it off to madison for me. However, they asked where i bought them from. I told them that I had got them from merlin. LBS then suggested that I check with merlin/madison as some of the stuff from melin (and wiggle) apparently doesnt come with a UK warranty? Spoke to merlin then, who said bring them in, and they'll have a look at them in their workshop, and then send them off if they need a warranty claim.

So it looks like I'm going to return them to merlin when I get a chance.

p.s. saving for hope brakes has begun. Hope customer service is amazing, and definitely worth paying the extra for. I could have sent everything off to hope and had it all back by now!!

Ah. Bit of a downside to on-line purchasing there then 🙁

I second the part about saving for Hope brakes!

Ok, so I dont have a set of very expensive xtr calipers, but bearing in mind the xtr stuff is mechanically the same as the cheaper calipers just lighter the same principals should apply with what I did.

As I had little to loose, I popped the pistons out and gave them a very good clean but when that didnt work I used a brand new very fine sharpning stone to very gently and carefully stone down the piston circumfrance slightly to ensure there was no high spots or burs and to ever so very slightly reduce the diameter, were talking 0.0005" here. That was very succesfull and Ive had no further issues with my LX calipers since, no leaks, nothing for over 12 months.