It has been discussed before, if not in this thread somewhere else in the forum. The ceramic pistons cannot withstand the pressure and start developing micro cracks, which firstly allow air to get into the circuit and ultimately lead to oil leaking over the pads.
From what you've read or experienced, does the micro cracking thing happen to most shimano brakes with ceramic pistons?
It all boils down to how hard you are on the brakes. Most of the XT/SLX sets I've seen here are used for XC/trail bikes, so the bite point changes are the first fail you notice as a result of the MC's bore deforming. But several of my friends riding DH, Enduro or just hitting hard on the brakes ended up with leaking calipers. Seems like the finned pads help postpone the unavoidable, which suggest temperature is a key factor on the micro cracks development.
The difference in use would perhaps explain why I haven't had significant issues with brakes in my Diatech -> Magura Julie (ugh 'cause shims) -> XT -> SLX evolution; I have experienced occasional minor pump-up with the SLX but zero leakage.
That bite point variation is different than the one I'm describing. Yours seem to involve to air in the circuit. It expands faster than oil when heated and moves the lever away from the bar. If the MC bore was deformed the bite point would be inconsistent, with the lever hitting the bar regularly.
I can't find any info on those outside their own site. I recall seeing a piece on them, maybe on Bike Rumor, a while ago, but so far my Google-Fu is failing.https://www.bicycle.braking.com/complete-systems/
Interesting.
26mm pistons, and swapable (different dia.) master cylinder pistons.
Bleeding didn't fix the issue. I still have the brake. Will see what can be done.
I even confronted a local Shimano fanboi devolved into a sales representative about this a while ago, and he LITERALLY went like
So at this point, I'm thinking of replacing my XT calipers with Zee calipers. This is the logic I'm following: I'm assuming that the mechanical advantage of the M785 levers is less than that of the M-640 levers. If I pair the M785 levers to M640 calipers, I will loose a little peak force of an M640 system, but it will be more than the M785 system. This will also preserve the pistons and seals on the M640 caliper, which I also assume is more robust than the M785....
Are the 2019 models still problematic?
Saint then? Though Jozz posted a link to a sweet deal on Maguras in my other thread, which I may jump on once I get a credit card number...
Squeezed them on a friend's bike and they feel awesome. I have zero ride time on them, but he's yeti sized and rides hard and is head over heels for them.
Want to try an old set of 755 levers which last forever? I'd imagine they'll connect right up to a typical shimano line/ fitting?
You know you're being pretentious when you start a sentence with that word.
Fair point; I was more saddened by the realization that I no longer have access to said fancy equipment.
Just built up MT5 calipers with M988 levers.
Awesome! Thanks for the input!
One more question, what fluid did you use, Shimano or Magura?
There's almost no doubt this is caused by the ceramic pistons as slim says, Shimano calipers never suffered widespread slave-piston leakage issues (in fact rarely had any caliper/slave issues) before they switched.
My take is to stick to 100% pure acetone (if addressing oil contamination) or 100% isopropyl for general cleaning. Auto brake cleaners can have additives which have little impact on auto brakes (with large surface areas and vacuum boosters) but may contaminate MTB brakes.
Yes I have two bike with them and have sold a handful to others that ride more often than myself. Bleeding is different the caliper loves to hide bubbles but with two bleed ports it’s easy to get them out, but a unique method after doing it a few times now. Lever is also different to bleed. But the brakes feel great and have the biggest pads so wear is fantastic. I pulled pads today that had been on a customers bike for a few months now and raced the BME last weekend which was 8300’ of descending and looked almost new. Still highly recommended the lever feel is really good.
Also used Shimano fluid
I've been trying to explain to a buddy that he doesn't want Shimano Brakes - he's lived in a relatively flat area all his life, and he's going to mountains. My own somewhat frequent near death experiences have made me pretty avid anti shimano, but he really really wants them. He's gonna do him, which means he'll get whatever he wants. He's liked the power some maguras have to offer, you said there are issues at both ends for shimano, he particularly likes the lever feel of shimano though. Are there any shimano levers that don't eventually deal with getting fucked that can be mated to a magura caliper for a somewhat reliable brake? I've looked at the spreadsheet for power listings, but I don't see much about reliability. I know you're in an area that's pretty hard on brakes though.
i don't think the new xtr stuff has been out long enough for long term durability. i'm curious about this too, but unfortunately not terribly optimistic. i'll likely be looking elsewhere for my next set of brakes. and i've been using shimano exclusively since saint first came out in 2003.
