Need Front/Rear disc brake help- What booster?

[UMI Performance]

Hey guys,

We are coming to the pros for advice..

We installed Corvette C5 brakes up front (12.8" rotor) and we installed disc brakes in the rear of our 79' Monte. We are having some vacuum issues and we have it narrowed down to needing a new booster. The booster is a dual diaphragm set up. The question is - should be looking at an upgraded booster that would be better for the rear disc brakes or just stick with the OEM?

 

[pontiacgp]

The booster doesn't affect the braking other then helping you push the pedal. The brake bias is important as well as the residual pressure so the pads don't back off. The other thing is the master and the size of the bores and the calipers you are using. Have you considered going to manual brakes? You'll have a better feel for the braking and it doesn't take alot of leg force to stop the car plus you loose the weight of the booster

 

[online170]

Kore3?

Might be the guys to ask, as they have a bunch of C5 setups going on things that aren't C5s.

 

[L92 OLDS]

OEM G body Cutlass brakes suck including the booster. Monte Carlos for some reason had a larger diameter (better) booster. I used a large dia dual diaphragm booster for an early 90's Caprice. It's a direct swap with no interference issues. I recommend new but if you get one from the yard, make sure to use the G body plunger. I like the feel and I don't have to stand on the pedal now.

 

[rwolf15241]

I will be using C5 brakes front & rear, looking into Hydro boost set up!!

 

[Blake442]

What master cylinder are you running?
If it's the stock one it won't do...
Did you install an adjustable proportioning valve?
The stock dual diaphragm booster should have plenty of assist, and may simply need replacement if it's original.
The larger diameter single diaphragm booster is not as effective imo...

I personally think rear discs are overrated, but installed them on a '84 SS at my old job.
We ran a master from a '79 WS-6 T/A and a stock booster and the pedal felt great.

 

[pontiacgp]

I personally think rear discs are overrated, but installed them on a '84 SS at my old job.
We ran a master from a '79 WS-6 T/A and a stock booster and the pedal felt great.

the advantage of rear disks is for racing conditions. With drum brakes the drum heats up and expands which ruins the brake bias which causes problem when setting up for a corner. For street use the disks have the advantage of never having to be adjusted but other than that they have no advantage.