What Master Cylinder and other components

[Phaeton]

Getting ready to purchase the rest of the items to finish off the Brakes on 67 chevelle.

Front brakes have C5 Corvette Calipers

Rears older Style Cadillac Calipers with E-Brake

I need to know what Master Cylinder you guy's recommend. Brand and bore size.

I do not think a booster type system will work. Motor is built and will not provide enough vacuum. Can go with Manual Master Cylinder if it will provide enough stopping power. Not opposed to Hydroboost but if manual will work why waste the money. Also what else do I need? Residual valves, Proportioning valve?

Thanks

[Pete68]

I'd go with the C5 in the rear too, Ive got that on my 68 Camaro along with the C5 booster and master cylinder and it works excellent. Mixing old rears with new fronts could create problems. C5 rear stuff is not so expensive...

Here is the write up on my 68

https://www.pro-touring.com/forum/showthread.php?t=61780

[Apogee]

The rear calipers that you are using (2-1/8" dia) have approximately 40% more piston area than the C5/C6 rear calipers (1.77" dia) and slightly less rotor diameter, so you effectively have about 1/3 more rear brake bias than the OE Corvette. This means that whatever you do at the firewall is going to be a bit of a compromise since your component balance isn't ideal front to rear. That said, you definitely should run an adjustable proportioning valve so that you can decrease your rear brake bias to avoid rear lockup as best you can. Most adjustable proportioning valves are limited to reducing the rear pressure to 57% of the front pressure, so there's only so much these can do depending on your setup. The more aggressive your car is setup, the more likely you are to encounter brake bias issues.

We would normally run a 7/8" to 15/16" tandem MC in a manual C5/C6 application...I would lean towards the 15/16" in your application to decrease your pedal travel caused by the larger rear calipers, however it comes at the cost of about 12% less pressure at the calipers with a given force at the pedal, so nothing is free. You also might want to consider staggering your pad compounds front to back with a lower coefficient of friction pad in the rear, something like a FF/EE or GG/FF front/rear CoF stagger. That might put you more in the middle of your range of adjustment on your proportioning valve.

Tobin
KORE3

[Vicinity]

Cadillac brakes are meant to stop a much heavy car than a Corvette.

Just throwing that in there.

[Apogee]

Cadillac brakes are meant to stop a much heavy car than a Corvette.

Just throwing that in there.

More accurately I would say that the Caddy is merely somewhat heavier and much slower than a Corvette...if I'm not mistaken, the 1979-1985 Eldorado's actually weighed about 3800# in standard trim, roughly 1200# less than the previous generation weighed (gotta love that 500 ci V8) and only 600# more than a C5 Corvette, but without nearly the same potential for speed.

Tobin
KORE3