Wondering why you couldn't installed a disc/drum master cylinder on a front drum car. I'd probably leave off the metering valve that is normally installed to a disc master cylinder.

Just a guess, but I would think the disk section would send to much fluid to the front drums. This would mean not enough to the rears, or inadequate braking in the rear.

The volumetric requirements are much greater for a drum set-up then a disc set-up. Also, the discs can tolerate more pressure than drums. The drums would lock up easier.

depending on how it was setup, drums use about 6 lb residual valves, which keep fluid right at the brakes-the springs can overcome the pressure so they dont drag-when you hit the brakes, there is no lag waiting for the fluid to hit the wheel cyl-disc brakes dont have the springs, so they use something like 2 lb valves
if you used a disc brake m/c, and the res. valving was in it, not the comb. valve, you would always have that lagging of fluid to the front brakes, because of a disc valving
use the right stuff for your brake system

The volumetric requirements are much greater for a drum set-up then a disc set-up. Also, the discs can tolerate more pressure than drums. The drums would lock up easier.

I thought it was the other way around, that disk calipers required more volumetric fluid than drums. :confused:

I thought it was the other way around, that disk calipers required more volumetric fluid than drums. :confused:


No because the wheel cylinders of drums are always returned to the same position, regardless of shoe wear. However, the pads on a disc set-up adjust to wear. This is why you need to compress the caliper pistons when changing pads which is not the case with a wheel cylinder when changing shoes.