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Brake master cylinder



Does anyone know of a 7/8 bore master cylinder that will bolt up to a stock corvette mounting system?

The reason I ask is that I have a 1968 vette with manuel brakes. I just completed a major overhall of the brake ssytem. New calipers, rotors , lines from Vette Brakes.

I also replaced the master cylinder with a new one at the same time.

The car does not stop as hard as I would like so I called Vette brakes fro tech help.

They suggested that if I find a master cylinder with a 7/8 bore which will increase my brake presure by about 20-25 percent.

Hopefully I can find one that will bolt up with out and modifcations to the firewall.


Big Fish

You might try contacting Muskegon Brake www.muskegonbrake.com They show a 7/8 bore master cylinder used on a 63 and 64. I don't know if they interchange, don't think they changed all that much. Yours calls for a 1" master, you might want to make sure that is what you have, it would be easy to get a power brake cylinder by mistake which has a 1-1/8 bore. You would have to remove the master cylinder and measure the opening at the piston. That would for sure cause hard braking. You might also have a problem with your proportioning valve which could also cause hard braking. Seems to me the 63-64 had front and rear drum brakes, probably did not require as much volume of fluid to work. A problem you might run into is running out of brake pedal because of less volume pumped with the 7/8 piston


Well-known member
Nov 24, 2001
63FI, 69BB
The 63 7/8 bore MC is for a "single" system. It has a single reservoir with only 1 "outlet". Your 68 uses a dual reservoir, one for the front and one for the rear. It also uses 2 outlets. Don't think you could adapt a 63 to work. Sounds like something else is wrong, as these systems functioned fine when new and working correctly. Chuck



I replaced all the master cylinder with a new unit. My car has manual brakes.

Also the rotors, calipers and pads are all new from vette brakes. The calipers are the x-treme dutyunits with o-rings (to prevent the air pumping problem). The rotors are the sport upgrade system wihich have the rotors with slots for gas relief. the pads are perfeomance hawk pads.

I also replaced all of the brake lines with new ones. The only thing I did not replace was the proportioning valve.

The brakes fell quite solid, but driving around I feel that brakes are not stopping as hard as I think they should be.

I talked to the Vette brakes tech guys and he said that the manual brakes use a 1 inch bore and if I switched to a 7/8 bore I would increase my brake pressure therefore increaseing the braking force.

So I looking for any ideas that will help.


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