master cylinder and booster help


Daily Driver
Dec 9, 2011
Battle Creek MI
78 malibu. Just converted fronts to 02' s10 2wd blazer twin piston calipers and the rear to 02' ls1 camaro twin piston caliper setups. Hearin a lot about the pedal is gonna b squishy or too hard. Is my booster gonna b ok with a canister feedin it and is my master gonna have to b changed? Runnin a big block with iron heads.....need all the help i can get!


Amateur Racer
Jun 8, 2004
Houston, TX
If you haven’t already done so, you will need to change out the proportioning valve. It is made for a rear drum set up and has a 10 lb residual valve in it to keep the rear brake shoes from backing away too much from the drum. Since you now have disc brakes in the rear the 10lb residual valve needs to be removed.

Here is a link.

For a master cylinder, you may need to upgrade to a master cylinder that has a larger reservoir for the rear disc brakes. Rear drum brakes require far less brake fluid capacity than rear disc brakes. Just remember that the rear reservoir is for the front brakes and the front reservoir is for the rear brakes. There are some 70s vette master cylinders that will bolt up to your vacuum booster and have the correct brake line outlets, but these are cast iron. If you want aluminum, you will have to go aftermarket. If using the vacuum power booster, you can go with a 1” bore master cylinder, if going manual, a 7/8” strait bore master cylinder is recommended.

LS6 Tommy

MalibuRacing Junkie
May 15, 2004
North Jersey
There is no distribution block or residual valve on a disc/drum A/G body. They have a combination valve & you need to change it to a disc/disc valve. The 70's Vette master cylinder you want for vacuum assisted power 4 wheel disc brakes is straight 1-1/8" bore. Call Master Power Brakes. They can set you up with the parts.


Similar threads Gear

Stickers & Shirts!!