Fluid volume doesn't necessarily relate to pressure. Most aftermarket (front) disc conversion kits use 3/16 front and 1/4 to the rear. You will find that the proportioning valves are designed for 3/16. I have installed numerous kits on a variety of vehicles and have not had a problem with this configuration.
Fred

Last edited by rfs56trk; 06/26/2010 11:27 PM.

1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine