Timbo S2 Posted June 1, 2009 Report Share Posted June 1, 2009 Hi, Put a brembo radial master cylinder on my trackbike. Towards the end of the last trackday, lever was comming back to the bar. I thought I'd rushed the bleeding, so took entire system off to bleed on workbench (keeping lines straight etc.). Put it back on yesterday, no bubbles from calipers, bleed well from cylinder bleed nipple, still not a lot of resistance. Put a syringe on the cylinder nipple, and opened, got a steady stream of bubbles without squeezing. I assume I have a leak and am getting air into system? Tied lever back overnight, and will go and have a look if that made any difference in a bit. If it hasn't, what do I do? I have a trackday on Thursday. Can I get mine serviced in time (doubtful). Anyone know where, in Norfolk region? Do I buy a new one, put it on, get the old one serviced, them put new one on road bike (gonna cost £220+)? Help! Link to comment Share on other sites More sharing options...
lorenzo Posted June 1, 2009 Report Share Posted June 1, 2009 Just a long shot, but what does the brembo one look like? There's a fair few on ebay that are fakes, cheap chinese ones, and can be told apart by the fact that they're cast rather than machined. Link to comment Share on other sites More sharing options...
Timbo S2 Posted June 1, 2009 Author Report Share Posted June 1, 2009 Don't think its a copy, marks all look correct... Got a bit more pressure, lever doesn't come back to the bar now. Will leave tied back for a bit more, and try again this afternoon... Link to comment Share on other sites More sharing options...
lorenzo Posted June 1, 2009 Report Share Posted June 1, 2009 master cylinder indentifying thread. By the look sof it, yours is the real deal although it's hard to say without seeing the texture of the machining. Link to comment Share on other sites More sharing options...
Timbo S2 Posted June 1, 2009 Author Report Share Posted June 1, 2009 Good to know. Gonna try slacking all fixings off, as I suspect I may have an air pocket trapped in the fixings somewhere... Link to comment Share on other sites More sharing options...
Timbo S2 Posted June 1, 2009 Author Report Share Posted June 1, 2009 Nothing as far as I can see. Will try with the adaptor in and out, its fully out at the moment, and lever still touches the bar. Fully in and its laughable! If nothing works, I'll run it up to the dealer and see if they'll look at it with their vacuum bleeder. It may work! Link to comment Share on other sites More sharing options...
Mrdrink Posted June 1, 2009 Report Share Posted June 1, 2009 Don't think its a copy, marks all look correct... Got a bit more pressure, lever doesn't come back to the bar now. Will leave tied back for a bit more, and try again this afternoon... The tube from the res to the MC looks a little iffy to me. theres a kink and doesnt look to be on the nipple all the way and doesnt have a clip. i dont know if it could cause your symptoms but it could be an air leak there,i would check it out. Also i see you have lockwired the adjuster knob but i would advise you to lockwire through the hinge of the lever. the little clips on the underside have been known to go missing leaving you with no brakes at the next corner After a night tied up like that it should be really firm. was it 2nd hand when you got it? Also all the standard brake MC's are cast bodies. the clutch and the more expensive brake mastercylinders are machined. Link to comment Share on other sites More sharing options...
Timbo S2 Posted June 3, 2009 Author Report Share Posted June 3, 2009 The tube from the res to the MC looks a little iffy to me. theres a kink and doesnt look to be on the nipple all the way and doesnt have a clip. i dont know if it could cause your symptoms but it could be an air leak there,i would check it out. Also i see you have lockwired the adjuster knob but i would advise you to lockwire through the hinge of the lever. the little clips on the underside have been known to go missing leaving you with no brakes at the next corner After a night tied up like that it should be really firm. was it 2nd hand when you got it? Also all the standard brake MC's are cast bodies. the clutch and the more expensive brake mastercylinders are machined. The tube from the res was procurred fron number 6, and had to be heated up to get it on in the first place! The kink doesn't seem to harm anything, there are no bubbles in the pipe. It was second hand (project cheap cheap trackbike!). It would appear that it is leaking from the bleed nipple, when I bleed alls OK until I shut the nipple and release the lever, them a little fluid weeps from the bottom of the nipple. I guess air is getting in when I pull the lever? Anything I can do as a quick fix? Would a dealer be able to bleed the system without touching the master cylinder bleed nipple? Link to comment Share on other sites More sharing options...
Timbo S2 Posted June 3, 2009 Author Report Share Posted June 3, 2009 PTFE tape is your friend... Sent the missus out to B&Q for some now. Will also get a clip on the res. hose, just to be sure. I assume just wrap a bit around the thread of the nipple? Link to comment Share on other sites More sharing options...
TheFlymo Posted June 3, 2009 Report Share Posted June 3, 2009 Sent the missus out to B&Q for some now. Will also get a clip on the res. hose, just to be sure. I assume just wrap a bit around the thread of the nipple? Yes, wrap it "with" the thread, so that the PTFE doesn't bunch up when you tighten the nipple. Also keep the tape on the threaded portion and away from the inner end of the nipple, so that it doesn't chop off and make it's way into the fluid. Link to comment Share on other sites More sharing options...
Timbo S2 Posted June 3, 2009 Author Report Share Posted June 3, 2009 Yes, wrap it "with" the thread, so that the PTFE doesn't bunch up when you tighten the nipple. Also keep the tape on the threaded portion and away from the inner end of the nipple, so that it doesn't chop off and make it's way into the fluid. Done. Doesn;t appear to be leaking, and getting a few more bubbles out and bit firmer at the lever. Have left it tied back again, will check in a few hours. Thanks! Link to comment Share on other sites More sharing options...
Mrdrink Posted June 3, 2009 Report Share Posted June 3, 2009 Done. Doesn;t appear to be leaking, and getting a few more bubbles out and bit firmer at the lever. Have left it tied back again, will check in a few hours. Thanks! Ah good news....i should have thought about that...my rear caliper bleed nipple did this. Link to comment Share on other sites More sharing options...
Timbo S2 Posted June 4, 2009 Author Report Share Posted June 4, 2009 OK, day done. Didn't get full lever pressure, though managed most of the day before the lever came back to the bar! So who refurbishes master cylinders, or can I buy a kit and do it myself? Link to comment Share on other sites More sharing options...
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