Hi Robert,
With the booster disconnected I don't get the vibration. I do know what the booster pushrod nub is and I understand that I need clearance but I've no idea how to check it.
The engine makes a lot of vacuum and even the lightest pressure on the brake with the booster connected gives some sharp braking. One theory that has been given to me is that the actual weight of the pedal is pressing on the brake slightly and this combined with the sharpness of the vacuum is applying the brake slightly.What do you think?
I've relized that changing the master cylinder is a good idea and I will try to find a stock looking replacement,however should I replace the booster also?The one which is on is the one that came with the car and is of a split two piece design with a clamping ring and the diaphragm in between.
Sorry it's taken a little while to gwt back to you.I've been busy getting the car ready for the Classic and Sportscar Show at the NEC