Hydroboost with 40MM master cylinder pressure checks

Did a brake pressure check. Bob Stone hydroboost kit with 40 MM master. This was after 2,500 miles. 1,350+ psi front and rear, Calipers are 80MM front 80MM mid, and 66MM Kelsey Hayes rear with park brake. This is with about 1,400 psi available from the steering pump. Mounts are Lambke style mid and Branscombe rear. Manny reaction arm system. Rear pressure improved after it got some miles on. Bob Stones hydroboost kit came from http://www.appliedgmc.com/

                                   

 

Graph shows what the pressure was with a P30 and modified 40MM JF9 master cylinder. 

 

          Master cylinder booster combinations and theoretical pressure

Force available from vacuum booster panic stop 1,473 lbs

Force available from hydroboost 1.56” piston diameter and 1,350 psi steering pressure 2,579 lbs

                                                                                     Bob Stone

                                          Vacuum  Booster              Hydroboost

                                                                                  

1.25” master cylinder          1,198 psi                          2,098 psi

34 mm master cylinder        1,048 psi                          1,835 psi

37 mm master cylinder           852 psi                          1,549 psi

40 mm master cylinder           761 psi                          1,332 psi

The hydroboost force does not include additional force that can be applied by the pedal

Vacuum boost force does include additional force that can be applied by the pedal

Later on we got a 1,650 psi steering pump and even more brake pressure