Had a new m615 brake do this, check and make sure the line fittings are seating properly. I found one that the olive was too far down the line so too much line had gotten smashed inside or line was held at an angle so olive compressed at an angle. Had to shorten it anyway, so I just shortened it and everything was fine.
Also if the fittings aren't tight enough they will suck in air. So check that first. Doesn't matter the model of brakes, if the lines aren't sealing at the levers (less of a chance in xtr calipers due to design) or calipers, you'll never get them working right.
Trek Marlin 29er
Like It, Love It, Want Some More Of It!
Did you cut the hoses?
If so, did you use new fittings?
If you are certain that you got all the air out of the calipers when you bled, check the hoses.
Make sure the banjo fittings are snug and make sure that the lines aren't damaged at the banjo and lever connection.
Shimano calipers do an excellent job of trapping air.
If your hoses are fine and you think you got all the air out of the caliper with whatever bleed method you used, you may need to cycle the pistons during the bleed process.
I like to cycle the pistons during the initial bleed and set up anyways.
Don't reset the pistons before the bleed process.
Instead, reset the pistons with the caliper bleed port open and with the syringe/hose/baggie + tubing/whatever you are using connected to the bleed fitting and with the funnel connected to the lever.
If you see bubbles when you reset the pistons, you have likely found your problem.
Push some fluid and move and reset pistons a few times until you are 100% certain you have an air free caliper.
Sometimes resetting the pistons prior to bleeding the caliper will still leave air in the caliper.
Best to have the caliper oriented vertically with the bleed port near the top-hanging the bike on a stand at the fork/downtube junction does wonders for orientating calipers so that air finds a way out.
Otherwise, removing the caliper from the frame can help too.
If you have the trail brakes then its the M9020. Have them warrantied, issues of changing brake points is a warranty issue and probably nothing you can fix.
I'd try and push both pistons out and cycle them a few times, sometimes bubbles hide there, bleed, test. Odd thing is that both are doing the same..
I've been using Shimano disk brakes since 2002, swear by them reliability wise. However, I've installed a few (including my own) new XTR's 9020 trail that had issues, mainly the right piston won't retract completely. Pushing it out and lubing the piston alleviated the issue a bit, but not completely, piston just wont retract fully. The rear brake changes contact point, lever will harden or contact point will be sooner upon consecutive feathering pulls. Can't replicate it while not riding. The damn thing almost make me crap my shorts, as I was riding down communication breakdown in Sandy Ridge, OR. I was feathering the brake, and in a left turn it just engaged sooner, causing the rear tire to skid almost making me hit a tree at full blast in a sideways drift. Could have been easily a vacation ender.
Bled the thing when I returned home, but haven't been able to fully test it. I've been itching to part with them and give a shot to the new Guides, but damn DOT fluid..
We'll see, if they don't behave, will deal with Shimano warranty..
By asookazian in forum Brake Time
Last Post: 07-16-2015, 08:04 AM
By brian2013 in forum 29er Bikes
Last Post: 12-03-2013, 06:42 AM
By stillkeen in forum Brake Time
Last Post: 09-20-2013, 06:35 AM
By fire02red in forum Brake Time
Last Post: 12-13-2011, 06:16 AM
By Ford Prefect42 in forum Cannondale
Last Post: 10-26-2011, 05:59 PM