I have a 67 tiger that hasn’t been driven very much lately because of a problem with my brake booster. I have rebuilt it once, and my dads shop has rebuilt it once to see if they could find anything wrong with it. It still has the same problem, when you drive the car, the first time you hit the brake pedal it works fine, when you let off of the brakes the booster wont release, until you turn the car off and get the vacuum to relase. They work fine until you stop again the next time then it happens again. This makes it undriveable. My dad wants to install a vacuum cut off in the line to the booster, so it will kill the vacuum, I dont want him to do this. I noticed on this forum someone said the new leather in the kits is too stiff, could this be the problem? and what could I do about it? Any help would be greatly appreciated.
The vacuum diaphragm is sticking in its boor, I would take the vacuum piston out and check the quality of the leather then I would polish the boor of the vacuum can.With some of the rebuilding kits the rubber that sits behind the leather is too thick this makes the piston too tight, to rectify this you need to slice the rubber in half and reinstall it back behind the leather so the piston is not as tight.
The large piston in the vacuum chamber is sticking, and I have also heard that the replacement rubbers can be too thick/hard.
Sorry to disagree, but the other advice (from the professionals in the UK) is not to polish the bore, but instead give it a fine honed finish to keep the grease in the grooves. Also, try to get a silicone based grease. Since I took this advice, I have not had a piston stick on either of my two different booster rebuilds.