Gold Lifetime Member
Join Date: Jun 2009
Location: Tomball TX, DeRidder LA
Re: Brake booster and pedal problem
Since you have a vacuum booster, you have two rods to play with. So far you have tried to adjust the brake pedal rod.
The other one is between the vacuum booster and master cylinder. Separate the master cylinder from the vacuum booster. Inside the vacuum booster you will see a little rod that pushes against the master cylinder piston. There should be about 1/16" gap between the vacuum booster rod and the master cylinder piston when everything is bolted together. Place a little piece of clay on the tip of the rod and reassemble the two together. Separate them again and look at the clay. There should be a thin film of clay (1/16") on the tip of the rod. The last time I did this I used a clay bar that is used to detail the paint job on a car. The rod should be adjustable by turning it. Once you get this rod correct length, now you can adjust the brake pedal rod.
Bench bleed your master cylinder.
Put everything back on your car and fill the reservoir with brake fluid.
Take the master cylinder cover off of the reservoir.
Watch the fluid intently.
Have someone press the brake pedal just a little bit. Just barely move the pedal.
You should see the fluid move in the reservoir as it is being forced down the brake lines as the brake pedal is pressed.
If you do not see fluid moving at all, and you pressed the pedal all the way to the floor or it stops before it gets to the floor, then the brake pedal rod is too long.
If you press the brake pedal more than an inch and then the fluid starts moving, then the brake pedal rod is too short.
You will have to fine tune this adjustment by driving the car and adjusting the rod to suit your taste.