copemech Posted June 14, 2012 Report Share Posted June 14, 2012 Have tried opening the the line on top of the master cylinder, major pain to do as it involves removing the top mounting screw to get enough clearance to fit a 14mm spanner. Had fluid come out when I pushed down on the lever but none otherwise, may have been a little bit of air in it but not much if there was. Closed the line back up while slowly pushing down on the lever same as if I would if it was a bleed nipple that was open Still no movement from the pistons afterwards It is well documented accross the brands what a pain in the rear these things can be. Many methods tried and failed. If were me, and I know pump is primed and pumping, I might next use a seringe to PUSH fluid(and air) out of the rear and hose up to the same banjo on top of the MC with the fitting cracked, then shut it. Here is the tutorial, yet you may know it already! http://www.youtube.com/watch?v=FcQq4U5ALyk Quote Link to comment Share on other sites More sharing options...
tony27 Posted June 16, 2012 Author Report Share Posted June 16, 2012 Pulled the caliper apart & gave it a good clean. Refilled the fluid & bled all the air out of the system, pads move but retract when the pressure is released. I got told to try something thicker than the disc between the pads to see if the pedal goes solid & if it does then I have a good system that just needs more pumping of the pedal to get the pistons to stay out Unfortunately the pads were already closer than that & I had to spread them slightly, pushing down on the pedal produced no real pressure & the pedal stuck down a couple of times. Looks like I'm only stewarding the trial tomorrow & won't be defending my club championship this year due to the problem, we could only drop 1 round & this will be the second I've missed due to this brake problem Quote Link to comment Share on other sites More sharing options...
copemech Posted June 19, 2012 Report Share Posted June 19, 2012 (edited) Pads should retract slightly with release of pressure due to the flex of the rubber seals on the pistons, this is only thousandths of an inch, enough to release the squuze! The fact that it stuck is more troubling, as the spring should push the piston back out if things correct. One may need to remove the MC and closely inspect the bore fore damage to the walls causing things not to build pressure and/ or bind up the new piston and seal. They need to be perfect for the most, as the tiny lips on the seal cannot hide imperfections. Oumping it with a rod on the bench and vice should produce a consistant pressure against the finger if it is pushing fluid if I an thinknig correctly, yet the displacement is small on these. Insure hose to caliper is not ruptured or expanding as in hemmoraged under pressure. Edited June 19, 2012 by copemech Quote Link to comment Share on other sites More sharing options...
tony27 Posted August 3, 2012 Author Report Share Posted August 3, 2012 (edited) Hopefully sorted brake, couldn't bleed it with kitted master cylinder at home & ended up ordering a new cylinder from Splatshop Spent a few hours with the Ossa importer a couple of weeks ago pressure bleeding it. Basically it involved removing the reservoir & fitting a syringe in place of it then forcing fluid through the system with the nipple opened & closing the nipple while keeping pressure in the system. It's really a 2 person job or at least 1 able bodied person & 1 with a broken leg job Seems to have given enough pressure to allow me to be able to lock the wheel by hand, may have contaminated the pads & plan on riding the brake on the workstand to heat them up then quenching them to clean them. Will have to wait until the new tank arrives to try this though Looking forward to finally getting a trial under my belt this year, won't be able to retain my club championship after missing 2 or 3 rounds but hopefully should be able to win at least a round or 2 before the end of the season Edited August 3, 2012 by tony27 Quote Link to comment Share on other sites More sharing options...
copemech Posted August 5, 2012 Report Share Posted August 5, 2012 If you did get the fluid on the pads and such, be sure to give them a good soak with the arisol brake cleaning solution, cause any of that fluid on them is not good. Glad you got some pressure at least! Quote Link to comment Share on other sites More sharing options...
tony27 Posted August 5, 2012 Author Report Share Posted August 5, 2012 Thats what I'm thinking has happened, could throw another set of pads in but that won't clean the disc Has taken a lot longer to sort than I would have liked due to my father in laws ill health & recent death. Looking forward to getting some use out of the bike before the VMX season starts up again, with any luck there shouldn't be any clashes of dates this year Quote Link to comment Share on other sites More sharing options...
tony27 Posted August 14, 2012 Author Report Share Posted August 14, 2012 Fitted graphics to new tank & started bike up on second kick. Ran the bike up through the gears with the clutch in on the bike stand to free it up & test out whether the brake was working, got it nice & hot before dumping water over the pads & disc. Will stall the motor in the higher gears but not in first if I get the revs up, get lots of noise from the brake in first. Happy that the brake works as it should now & that I'm actually going to get to ride the trial I'm down to set this weekend Quote Link to comment Share on other sites More sharing options...
tazz229 Posted September 14, 2012 Report Share Posted September 14, 2012 Put the pads in the oven Gas mark 7 for 20 mins, clean the disc with some carb cleaner or alcohol hey presto sharp brakes again. Quote Link to comment Share on other sites More sharing options...
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