This is concerning my brothers zed, not long ago after not driving his zed for a long period of time, he went to take it for a drive and realized his brakes were not working. After attempting to bleed the lines to no avail we realized that with the pumping of the brake pedal that air bubbles were rising up in the Brake Master Cylinder, hence no amount of bleeding would clear the lines of air. So I suspect failure of one of these pistons or seals that go back into the brake booster. A member has a second hand brake master cylinder & brake booster for sale, so my question is do we need to replace both items or just the BMC section of it? I don't know a great deal about this any info is welcomed Cheers
You have probably damaged or dislocated a seal. It is also very easy to damage a seal when you bleed the brakes. Normally the piston moves only a very short distance. When you open the bleed valve, the stroke is much longer and the area where the piston has not travelled may be a bit rough. Pull the cylinder out and take it to the brake place for a clean, check and new seals.
yes that makes sense. I will see what he wants to do. I was going to buy a second hand part for him and replace it , so I take it the brake booster is fine just the bmc part in the pic needs replacing? He isn't mechanically minded & lives 6 hours drive from me & I'm planning to go see him soon to replace that part along with a plenum pull to replace leaky hoses and install coilovers etc. So I don't need another brake booster for this? Cheers
Just the BMC Assuming he has bled the brakes correctly, his callipers aren't leaking and his fluid didn't get too low from pad wear, he will only require a master cylinder rebuild. Has he bled the master cylinder at the piping, or the ABS unit in the cargo area? I would check all brake components first for fluid leakage.
Last time I visited him we checked those things also, bar the Abs, and appears to be no leaks. Thanks for the responses I believe he just needs a rebuild or replacement of the BMC components, just wanted to be certain before purchasing . Cheers
