wonso79

What's the difference between the dual master cylinder for a drum and for a disc? I just recently purchased and install a dual on my 65 for my drum brakes but was just curious as to why there is a different one for the disc brakes?

Cruzzar

If I remember correctly, the drum portion has a residual check valve and the disk portions does not. If that is backwards, someone correct me. I'm not sure you can tell the differance between the two just by looking at the outside of the master cylinders.

chockostang

You are exactly correct.

Drum masters have a 10 pound residual in both ports. The Disc brake master only has a residual in the front port (Rear Drum Circuit).

Drum masters have equal size "Bumps" on the lid, Disc Masters have a larger bump on the front, smaller on rear.

Dan @ Chockostang

wonso79

Thanks, I thought they looked the same from the outside!

Bosko

I did not realize that there is a residual valve in the master. Great information to know!

I am ordering Wilwood disk brake kits, front and rear, from Summit today. I have a 1971 with four wheel manual drum brakes that these will be going on. I was planning on upgrading the master to the OEM style for front disk with rear drum with a vacuum power booster. I suspect having the residual check valve won't hurt the disk brake conversion.

Any advice or cautions that could come back to bite me?