I’ve had shimano brakes on all my bikes for the last few years – I’ve generally been happy with their performance and maintenance requirements.

Unfortunately work and family commitments have meant I’ve gone from riding 2-3 times a week to 2-3 times this year to date and all my newish shimano brakes (2 x XT and 1 x Zee) are now all squealing and leaking oil onto the rotors presumably as a result of the seals drying out. I’ve tried bleeding the brakes and cleaning the rotors but (as you’d expect if the seals are leaking) this hasn’t really helped. Interestingly the old set of Lx (2010 vintage) on my wife’s bike are fine.

I’m resigned to replacing the callipers (and the newest set is just out of warranty) but I don’t want to do this if I’m just going to experience the same failure again.

Does anyone know whether shimano have resolved this issue? Was it just a particular batch with dodgy o-seals or is it a design fault? The brakes were fine when in regular use but sadly thats fairly unlikely for me in the near future – particularly on all 3 bikes…

I’ve never had this issue. Is it something you clean the bikes with perhaps, Muck

Trimix – Member
I’ve never had this issue. Is it something you clean the bikes with perhaps,

+1

It’s a well known issue with shimano brakes – they’ll replace them if it happens within the 2 year warranty period.

It’s not cleaning (I rarely do that on the singlespeed!) – it seems to occur after longish (months) periods of lack of use.

My question is whether it’s still happening or whether they’ve resolved the issue – I suspect not…

I’ve seen this on several Giants of a certain generation (few years old) where after a few weeks, the pads start squealing and lose effectiveness. This is a known issue on certain brakes where the seals seep fluid into the pads causing contamination.

In all cases the calipers were replaced under warranty but the problem returned quickly. In the end, it was solved by swapping the entire brake for the current generation Deore, which have shown no issues.

You _can_ contaminate pads through poor maintenance, but this was a real problem. Fortunately, none of the current generation Shimano brakes I’ve seen show any sign of this now.

I’m regularly seeing the new brakes with traces of sealant around the joints and fittings, and not had any recently sold bikes returned with leaks, so hopefully they’ve sorted that issue now.

Shimano will tell you that using non-Shimano oil is what kills seals, I’ve got a 100% reliability rate with Shimano oil and a 100% failure rate when I’ve tried Halfords mineral oil so I woudnt argue with them.

My latest warranty replacement M8000 are about perfect, completely consistent bite point and reliable as a reliable thing.

Bike shop mechanic here. (and Shimano fan generally)

Seen lots of failed shimano brakes in the shop, virtually none of which have ever been touched from new so have the original oil.

The rear brake on my cannondale trigger was leaking on delivery and was replaced with no issues.

However I haven’t seen failures with any of the new generation ones so anecdotally the problem seems to be fixed now

Some anecdotal evidence they can be fixed by splitting the caliper and replacing the o ring that sits between the two caliper half’s.

Have had no issues with my m7000s.

see this article

http://blueliquidlabs.com/repairs/solving-that-brake-squeal/#more-539

That’s the one^

Thanks for the responses everyone – looks like it’s worth investing in new calipers.

A quick google suggests M8000 calipers are compatible with M785 levers; has anyone done this?

The Shimano tech support guys at Ard Rock assured me the m7000 callipers work with the m675 lever, so almost certainly the m8000 calliper will work with the m785 lever.

Still happening. Had to warranty my rear after 5 months use. Bike was only ever hosed down and never touched the fluid.
Looks from Madison site that entire brake range has been updated though, as they had no stock of my model and lbs had to order from CRC. Pictures of upcoming models look totally different, so hopefully redesign will sort issues.