Vacuum Booster Question

[Johnjan]

Trying to trouble shoot the Baer 4 wheel disc setup on my newly (or nearly) finished '68 Camaro. Brakes are bled, lines are solid, yet brake pedal goes almost to the floor and require a LOT of pedal pressure to stop the car. With vacuum line disconnected, pedal is high and hard, but I've not driven the car that way. Don't know the bore but the master cylinder is the one supplied by Baer for this system, so I'm assuming it's correct for the 2 piston PBR calipers. Booster is a 9" single diaphragm.

So here's my question - how much engine vacuum is required for the booster to work effectively?

What else should I be looking at?

Thanks!

John

[intocarss]

I've read 10-20" of vacuum depending on what booster you have

[MCB Matt]

The master that used to be supplied by Baer is too small of a bore! On a 9" single we typically run 1 1/8" master.

We have several from $49-195 for a NICE bolt on lid

If i can be of any help send me a pm!
Matt

[mario65]

I have 10.5" vacuum in gear and 14-15" in P. I run the tuff stuff 9" dual diaphragm booster that DSE uses with their kit. I have a Wilwood master and Wilwood brakes. The booster works great. In fact I am having to get used to the lighter pressure to stop the car.

[MCB Matt]

Typically we like to see no less than 15" steady at idle to run a booster.

Matt

[Skip Fix]

My factory 79-81 Trans Am 4WD dual diaphragm booster works good 10" and above getting around 9" at idle gets iffy intermittently.