tombo46 Posted November 9, 2007 Report Share Posted November 9, 2007 Ive had a rubbish front brake for a long long time now and its finally got to the point where im fed up with it. Ive replaced the pads twice, cleaned the disc with brake cleaner, replaced the fluid and bled the brakes twice and its still rubbish. there is plenty of pressure on the lever, just as much as anyone else riding a beta so i cant understand where the problem is. could it be something wrong with the disc? I have to slide the master cylinder right down to the bend in the bars just so I have enough leverage to lock the front wheel (with some effort). anyone got any idea's on what I could do? All the best Tom Quote Link to comment Share on other sites More sharing options...
betarick Posted November 9, 2007 Report Share Posted November 9, 2007 Are your caliper pistons moving ok and not siezed! as this could be why you after apply so much pressure on lever! Quote Link to comment Share on other sites More sharing options...
gez Posted November 9, 2007 Report Share Posted November 9, 2007 First I surgest not using brake cleaner this does leave a surface film , quickest way is to ride the bike around applying the brake untill hot then quickly quench the brake disc with cold water. Quote Link to comment Share on other sites More sharing options...
scorpa3 Posted November 9, 2007 Report Share Posted November 9, 2007 First I surgest not using brake cleaner this does leave a surface film , quickest way is to ride the bike around applying the brake untill hot then quickly quench the brake disc with cold water. Really, does that work? Having changed all of the things that you mention, it could be the brake line failing. If the integrity of the pipe has gone, then the pressure will be being wasted expanding the pipe and not being applied to the piston. Quote Link to comment Share on other sites More sharing options...
yamahaty250xox Posted November 9, 2007 Report Share Posted November 9, 2007 i agree with gez however i wouldnt put cold water on the disk it may couse it to crack use a solvent to clean the disk and then run on flat ground until the disk starts to smoke! leave it to cool if still no good try agen if still no good give up Quote Link to comment Share on other sites More sharing options...
kevin j Posted November 9, 2007 Report Share Posted November 9, 2007 Having changed all of the things that you mention, it could be the brake line failing. If the integrity of the pipe has gone, then the pressure will be being wasted expanding the pipe and not being applied to the piston. nope, that just makes it spongy, will still develope the same final pressure. Now, if you have a piece of lining of the hose causing a restriction, can stop the flow. but I'd focus on cleaning pistons pads and disc. kcj Quote Link to comment Share on other sites More sharing options...
gjbiker Posted November 10, 2007 Report Share Posted November 10, 2007 Could also be the master cylinder piston seals? Checklist; Replace- seals (master and slave), brake hose, brake fluid, pads. Thoroughly bleed system until 100% sure there's no air. Clean disc with solvent cleaner then hot soapy water, dry with best guest towel. Brakes should now be tickety boo ? No ?? Buy a Gasser GJ Quote Link to comment Share on other sites More sharing options...
tombo46 Posted November 10, 2007 Author Report Share Posted November 10, 2007 cheers everyone, ive heated the disc up and poured cold water on them before and it does give me a better brake but still nowhere near where it should be. the brake pads are new so now problems there. Ive cleaned and greased the pistons in the caliper too and are all free moving, i pumped them all the way out and pushed them back in again and they all seem 100% How do I replace the seals in the master cylinder? havnt got a clue hehe. Thanks again. Tom Quote Link to comment Share on other sites More sharing options...
mad4it Posted November 10, 2007 Report Share Posted November 10, 2007 If you remove the brake lever and take off the rubber boot you will see a circlip remove this and the piston draw's out ,there will be some resistance so use some long nose pliers to get a good grip on it. Once removed replace the seal and re assemble in reverse order job done ! Quote Link to comment Share on other sites More sharing options...
tombo46 Posted November 10, 2007 Author Report Share Posted November 10, 2007 cheers!! Quote Link to comment Share on other sites More sharing options...
rokhopr Posted November 13, 2007 Report Share Posted November 13, 2007 I had a similar maddening problem. Turned out to be the bleed nipple was ever so slightly leaking fluid onto the pads\disk. Put some teflon tape on the threads and problem solved. mpc Quote Link to comment Share on other sites More sharing options...
hovis Posted November 16, 2007 Report Share Posted November 16, 2007 i had a crap front brake on my gas gas........... but that was down to the fork seal leaking oil onto the disc, are your fork seals ok? Quote Link to comment Share on other sites More sharing options...
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