rustytoolss
Well-Known Member
Just put 2.75" calipers on my car. Should I use the 1 1/32" MC , or the 15/16" MC ? this is for a manual front disc/ 10" rear drum system. Thanks
Fyi the area of the 4 pistons in 1 KH is about 8.4 sq in and your single 2.75 caliper is about 5.9 sq in.
15/16 piston area is about 3
1 inch piston is about 3.14
1 1/32 inch piston Is about 3.25
Simple math can get you the respective ratios for the combonations.
Then measure you brake pedal and get its ratio
A little more math and you can get final ratio.
I have the same set up on my 68 Barracuda. Wilwood front disc. 11” rear drums with Adjustable Summit in line valve to the rear.I don’t have a residual valve on either car. Got all my parts from Napa except the prop valve from summit.
What master cylinder did you get a NAPA that has 15/16" bore for manual brakes ????I don’t have a residual valve on either car. Got all my parts from Napa except the prop valve from summit.
Do you mean the long spring and the 2 steel pieces that go in the cups?Residual valves were installed to keep the wheel cylinder rubber cups in contact with the cylinder wall, preventing leakage.
Newer W/Cs have a spring with a "spreader" to mechanically hold the cups against the cyl wall, no need for residual valves.
If you know your rear W/Cs have the spreader spring, no residual valve needed.
Not sure, - or no spring, install the R/valve .
The residual valve will have no effect on W/Cs with the spring .