Don, et. al. -

Return spring is strong.

Did some digging on Rockauto.com and Raybestos.com, and found that the most likely match is their part #MC36317, a manual disc/drum MC with a 1 1/8" bore, used on '69 Camaros and 69 - 74 Novas. It matches visually and has the same center to center measurement for the mounting bolts (3 3/8 as I measured it, 3.4" according to NAPA's tech line).

I could also use Raybestos MC36376, what the tri-five guys call the "C3" MC, used from '69 - '76, with a 1" bore.

I'm aware that I have to match bore size, mounting bolt spacing and post thread size, but at least I have 2 possibilities now. The final call will come when I remove the old MC and get the specific specs.

There's actually a really good thread on Master Cylinders on trifive.com http://www.trifive.com/forums/showthread.php?t=33201

I know that a smaller bore MC is supposed to be better with manual brakes at the expense of pedal travel, but I'm going to wait until I pull the MC to see what was on there before I order a new one. I was going to see if the problem was fixed with a new proportioning valve, but since a new MC is only $30 or so and I don't know how old my existing one is, I might as well replace it while I'm under there and dirty.

Chris

Last edited by Barsteel; 03/27/2013 10:41 AM.