vfrflanders Posted May 7, 2012 Share Posted May 7, 2012 On a trackday I hit a tirewall and the bike felt on his right side. The brake lever took a serious hit and was even bended. I replaced the bended lever. Although the brakes felt spongy, they seemed to work (because the bike was on his side, I thought some air went into the lines). Because I needed to bleed the lines, I took the oportunity to install speed bleeders. After bleeding several times the lines, the front brakes still feel spongy. First I thought I did something wrong with the speedbleeders, but the bleeding of the rear brake only took me 5 minutes and worked perfect. Started to look into the "problem" - leaks, clogged fluid passages, strapped the lever during one night to push any air out. Nothing... Their is only one thing I noticed: when I took a few times the bike of his centerstand, the brakes sometimes didn't have any brakingpower at all when I pressed the lever. What's the problem. I don't know. Still air trapped I can't get out? Damage to the master piston in the master cylinder? Any advice welcome. Link to comment Share on other sites More sharing options...
Member Contributer mk2davis Posted May 7, 2012 Member Contributer Share Posted May 7, 2012 The only things to come to mind, and I'd bet you did this already, is to bleed both sides of the calipers. I know when I did a bleed job on my gen 3, the fluid running out of the outside of the left caliper was crystal clear, but my brakes fell like doodoo. It wasn't until I went back and forth from inside to outside of the same caliper that I saw any improvement. I hope this helps. Link to comment Share on other sites More sharing options...
Member Contributer AnikMankar Posted May 8, 2012 Member Contributer Share Posted May 8, 2012 Check the front left valve...that has a tendency to leak Link to comment Share on other sites More sharing options...
vfrflanders Posted May 8, 2012 Author Share Posted May 8, 2012 Rechecked everything, No leaks. I first thought it was the master piston (but how can do you check this?), who couldn't make enough pressure, because it was damaged in the accident. The fact that moving the bike (taking of his centerstand), changed the feeling in the lever (moving fluid/air in the lines because the bike "moves"), I still think some air is trapped somewhere (banjo, T junction...). Going to "strap" the lever again, hope I can push the air out. Anyway, help is still welcome (weblinks, how the analyse different brake problems...) It would be stupid the replace (not damaged) parts, if some stupid airbubble might cause my problem... Link to comment Share on other sites More sharing options...
vfrflanders Posted May 8, 2012 Author Share Posted May 8, 2012 Had a strap around the lever for 12 hours. Spongy feeling was gone, untill I moved the bike from it's centerstand. Could pull the lever the whole way, only little braking power. Could build up braking power if i pulled the lever once again. This happens every time I move the bike, even a foot. Checked on other sites: this still seems to be an "air" problem. From ther information I gathered, this has nothing to do with a master piston failure. If I had a front/back seal failure, the lever would react differently. Running out of options now.. Link to comment Share on other sites More sharing options...
Monk Posted May 8, 2012 Share Posted May 8, 2012 IIRC it should be done while on the side stand. Has to do with letting the air escape to the right(that's the 6gen though) Link to comment Share on other sites More sharing options...
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