Had a set of these this year.
The rear has been great but the front has constantly howled!
It has felt like it is contaminated so was sent back under warranty.
Had new caliper sent out,fitted it and bled as Shimano docs.
Initially it was quiet then the howl has returned!
What next?
No spongy brake,firm lever just squealy!
Thinking adaptor is not a perfect fit on caliper as used adaptor from TRP Spyres.
They are 160mm rotors.
Bigger gap on disc on one side and pads don’t touch evenly all round.
Any problems out there?
Thanks,
Max

What’s the braking performance like? If you pull and hold the front brake, then push bike forward does it lock? Or does wheel keep rotating with high pitch squealing?

It does grab but honks a bit when pads grip.
Does feel contaminated but there is no sign of any oil on disc or pads!
Max

Bigger gap on disc on one side and pads don’t touch evenly all round.

I would suggest sorting that out first.

Switch the F & R pads (and maybe rotors) to see if noise persists.
My 785 squeal was solved by giving the pads a light sand on a flat surface.

When I say gap I mean the way the caliper is aligned with the adaptor.
The rotor is central in the caliper and disc free running.
It is like the adaptor is pushing the bottom half of the caliper up.
It means not all the pad is contacting the disc.
These adaptors were originally fitted on TRP Spyres.
Maybe thinking a different adaptor will do or maybe ditching them all together and fitting 140mm rotors?
Max

Sounds to me that the pads are glazing due to lack of use, throw some water on them and do some hard braking to see if the noise goes away.
What rotors are you using, I find rotor with bigger holes (as opposed to lots of small holes) tend to clean the pad surface better.

The pads are brand new as they came with the caliper that was warranted.
The rotors are 160mm xt ice tech.
I rode down the street and gave them a bedding in with a few hard stops with no squealing.Just a gradual slowing of bike.
Rode my normal trail and within 10 mins were squealing like banshees again!
The back brake has been sound with the same components.
Maybe a more thorough break in period is required?
Max

got 785’s on the mason and they only make a noise (initially) when
wet as all shimanos seem to do.
I’d get the mount alignment checked then check the adapter is square
and true.

Yeah,
Feeling it’s an alignment issue or maybe the adaptor.
I shall have a play.
Thanks for the advice everyone.
Max

Well.
Had a play.
Swapped rotors and pads around.
Same noise.
Roughed up pads and disc.
Still the same.
Checked adaptor bracket.
Even wear around disc even though a little un even wear on pads.
Adaptor can’t go any closer to disc as will catch on spider on disc.
It is a new fork so my next step is to find a disc facing tool.
I think the pad is hitting disc at an angle,causing the noise.
Thanks,
Max

I had this on some Deore’s and it turned out to be a weepy olive, not bad enough to affect the lever feel but enough to contaminate the pads and rotor, when I checked it the olive was a bit wonky and didn’t seal 100%, a new olive cured it..

Hmm,
Mite try that.
I have used existing olive.
Would need to trim cable but it’s worth a try!
Thanks,
Max

I had this for months. New rotors, pads, sanded the rotors and pads and nothing would stop it. I did eventually notice a small amount of what I could only assume was fluid on the back of one of the pads. Replaced the caliper and it’s not squealed since.

It seems like these calipers are very prone to leak a very small amount of fluid. Check the back of the pads…

Well,
The noise has surfaced again.
Dissapears when I burn it off Down a big hill.
Had a caliper swapped under warranty.
Replaced olive,replaced pads (again) and did a good hour or so of bedding pads in.
All was quiet then a sudden squeak again.
Burnt pads in then quiet then an occasional squeak.
No power loss in lever.
Checked caliper and back of pads and no noticible oil anywhere?
What now?
The fork is new and the 15mm skewer has a tendency to come loose!
Could it be something else?
Alignment?
Thanks,
Max

You had contaminated pads on the original caliper which you then had replaced . You didn’t replace the disc which would also have been contaminated . The pads on your new caliper have now been contaminated by being in contact with a contaminated disc .

Had exactly the same issues… Lbs did some research for me… Their conclusion is Shimano brake road pads/rotors don’t have sufficient carbon. DT Swiss do some aftermarket pads specifically to compensate this… LBS also took a blow torch to the rotor! Repeated heat up, brake hard, cool with water. I am now astounded by the performance and silence of the brakes… If you’re anywhere near South Oxfordshire, Alex at Mountain Mania in Goring is exceptionally patient and curious enough to research and solve the problem

Cleaned the disc first time.
And cleaned again with disc cleaner with new pads.
As I said working fine with no squeak and periodly coming back.
Wouldn’t it squeal all the time if the rotor was contaminated?
Max

So, second ride in and I have discovered a leak in the caliper.
A small pool of oil seems to be coming out of the join of the caliper.
The caliper doesn’t seem to line up,like the two halfs have not put back together properly!
Hopefully the wait isn’t going to be too long this time.
First CX race this Friday.
I shall be using the 29er!
Thanks for all the advice.
Max