Has anyone got experience of resolving problems with the brake booster and I dont mean just sending it off for someone else to rebuild. I believe that my booster is not allowing the piston closest to it from the master cylinder to go all the way to the "rest" position. I have never taken one apart and do not know if this is a common fault.
How have you established it’s a booster problem and how does it (the “problem”) it manifests itself ?
All my calipers have been rebuilt with new pistons and seals,the master cylinder was in great shape so just the seals have been renewed. when I push the brake pedal only the last 1/4 has any resistance. This resistance is translated to operating the front brakes ( which can also be bled succesfully). so I have deduced that the "first" master cylinder piston is not starting its travel from its correct rest position but instead somewhere else between that position and its end position, because it can displace the brake fluid to operate the front brakes and this happens at the end of the pedal travel. Another symptom that corresponds with my theory is that the second master cylinder piston which operates the rear brakes, now has to contend with the extra force pushing it away from its "rest" position by virtue of the increased spring force of the spring of the front master cylinder piston which is now sitting much closer to the rear piston. So the second piston has a new rest position which is the end of its travel and can not displace any brake fluid to the rear brakes no matter how any times the brake pedal is depressed. This shows up on my car as no rear brake function and no ability to pump fluid out whilst bleeding the rear brakes, but if the the rear caliper bleed nipples are opened then brake fluid can exit via the force of gravity as there is no blockage.
Did you personally rebuilt the calipers and the MC (+ booster) and know they’re assembled correctly ? I assume all brake hoses were replaced during recent(?) system overhaul and if yes, I assume pedal-to-booster and booster-to-MC pushrods adjustments were checked too, correct ?
Yes I personally rebuilt the calipers and MC but did not touch the booster. I did not alter the push rod adjustments. The thing I do not understand is that when I first did it the whole system worked fine, but a couple of months later it has reverted to the same issues as before.
