ok some of you know what i am doing to my car i have just swapped to a mustang 2 frontend with 11in. brakes and gm metric calipers i was wondering why i should switch to a disc brake master cyl when it has a 15/16 piston and the drum has a 1in i would think the 1 inch would be better for a disc/drum manual brake setup and i would just use a adjustable proportioning valve , also what has the longest foctory rubber hose for gm metric calipers i got a set for a 84 olds cutlass and they are pretty short , thanks for any help guys
the drum brake mastercylinder has a residual pressure valve in each circut. it holds a few psi in the lines that will cause a slight drag on the calipers. the smaller bore require less effort on the pedal but a little bit more travel.
And discs usually require more fluid volume, that's why disc/drum MCs have a large reservoir (disc) and a smaller one (drum). A lot of guys run drum MCs with discs but I figure if they weren't needed the bean counters at Ford would never have let the engineers change the MC.
The size of the master cylinder and the size of the wheel cylinders (and caliper bores) determine how much pressure you have against the friction surfaces. Using a larger bore on the mastercylinder will give you less force and less travel. The smaller bore on the master cylinder will give you more force and more travel. Disk brake master cylinders usually have more travel to compensate for the larger bore of the calipers. Disk brakes need a lot more force to operate than drum brakes do because they are not self actuating. With drum brakes the turning drum helps to apply the brakes. Not so with the "pinch" of disk brakes.
thanks guys i am going to buy a rebuilt disc/drum manual master cylinder for a 77 maverick for 10$ at auto zone
