I'm having a problem with my front brakes , i've just fitted a set of p4 calipors from a 996r but when i was bleeding them by opening the nipple and pumping the lever the fluid was coming out from the threads and i've tried the nipples from my old calipors but its still leaking , anyone ever have this problem ?
Both sides or just one nipple? If it's both sides I'd be very surprised hat they have both got a problem. Is the thread on the nipples correct? Not tight enough? Mind you, DO NOT over tighten them and risk shearing them off!
yes it seems to be both of them , threads are ok and its when i open the nipple and pump the lever the fluid comes out at the threads
I am not surprised fluid comes out round the thread when they are open. How about when they are closed? if it comes out then, that's a problem.
The nipples seal with a metal to metal seal at the internal end , the threads are not the seal, you do not put tape on the threads. The fluid can leak when bleeding , this doesn't matter when bleeding the old fashioned way, as long as they don't leak when you tighten them down.
agree it is the seat where the nipple seals not the threads would not worry about fluid around threads when nipple is open only when the nipple is tight as it would not be seating properly and that could be a problem as said not a problem if bleeding the old way ie applying pressure on the system from the master cylinder if bleeding by suction from the bleed nipple itself it can suck air in and be a pain friend bought an expensive (well by my thoughts )vaccume bleed pump and had loads of hassle thinking he had air leaks in the system when it was sucking in air around the threads diagram below shows the nipple seating and sealing on the one on the right
You do not say whether you are using new/replacement nipples, but I had this issue when I bought new nipples, for the reason explained above - the chamfered angle of the new nipples was very slightly different to the originals and for that reason, they did not seal properly
But B is correct isn't it? That's how AP callipers work anyway on a diagram I posted on here a while back.
see what you mean on the Lockheed diagram thought A would have more of a sealing face ? but anyway I only put up the diagram to show it was not the threads that seal learn something new everyday
Two mating tapered surfaces are harder to machine for sealing faces, a smaller cone into a larger hole forms a seal even if there are slight manufacturing inaccuracies as it forms the seal as it tightens and takes out any high spots :smileys:
