center lock disc issue

bobbydigital · August 2018

I cannot get these rotors to line up, or shall I say I cannot get the caliper/pistons to operate centrally on the disc.

One of the pistons always touches the disc first and pushes it slightly.
Disc is RT 81 Ice tech and is brand new.
I have tried multiple brakes with different calipers but get the same results.

The disc is true.
Pistons on the calipers move equally off of the disc.
Currently using a m785 brake, tried with old style m395 which have br 477 calipers and tried with m615 calipers, all end up touching the disc slighty on one side before the other, any one ever had an issue with center locks?

CitizenLee · August 2018

Have you done this?

Loosen caliper bolts
Apply brake
Tighten bolts
Release brake

steve_sordy · August 2018

It works for me too.

bobbydigital · August 2018

I have tried that method many times but never find it lines up correctly, maybe that's just me but I have noticed a leak on the m785 caliper so not much use now.

kajjal · August 2018

What you are seeing is normal, unless it is very pronounced. Sometimes you need to set the calliper up by eye to compensate for this, assuming it is not faulty in some way.

bobbydigital · August 2018

No it isn't major, maybe 0.5mm off center so one side touches the pad ever so slighter sooner than the other.

I found a m506 that lined up nicely but feels a bit spongy so might need a bleed, never had issues before, tempted to try my other wheelset which uses 6 bolt disc to see if it chances anything, the ice tech discs look a tad thicker.

The m506 came off my 26" xc which had 6 bolt disc and it felt really solid, put on the center locks and it's not so great, seems a bit strange.

02gf74 · September 2018

Bobbydigital wrote:

the ice tech discs look a tad thicker.
.

I seem to remember that it is the case and need matching shimano callipers.

Having said that, I have a pair of them, these are the earlier model without the fancy alloy cooling fins, and haven't noticed them being thicker. They are running with matching xt calliper.

....but it as long as the pistons move apart to let the disc in, it shouldn't matter as the hydraulic pistons are self adjusting.

bobbydigital · September 2018

Yeah I'm just a bit ocd about brakes, I like minimal level travel and sometimes find the m395 style levers feel better than the m785 style, I tend to pump the brake off of the caliper in order to reduce pad travel.

steve_sordy · September 2018

Bobbydigital wrote:

Yeah I'm just a bit ocd about brakes, I like minimal lever travel ..............

Weird isn't it, how we are all different?

I don't mind a bit of lever travel, as long as the lever goes hard at the end. I prefer to feel the brake start to engage almost as soon as I move the lever and then progressively get firmer and firmer. I haven't measured the travel, but just visualising it now, maybe an inch of travel (25mm) from fully off to fully on?

My 11-year old grandson is the same (of course he is, I trained him and set up his bike!) But his mates nearly always go OTB when they test ride his bike. They complain "why are your brakes so fierce?"

cycleclinic · September 2018

caliper mounts may need facing OP.

bobbydigital · September 2018

I am used to sporty motorcycles that have okay to good brakes so always go for the 10mm of travel if I can, Shimanos seem a bit hit and miss but I do always buy them used.

@thecycleclinic

It is difficult to move the caliper left and right on the I.S to Post adapter so could be an issue there, I think I have some new adapters somewhere but the fork was brand new, only done maybe 100 miles, Salsa Firestarter.

Is there any known issues with air in the lever of the m506 levers?
They are just not as solid as I would like, fully bled, burped with the funnel, does anyone ever do a bleed from top to bottom rather than shimanos bottom to top method?

center lock disc issue

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