[ricks69goat]

I have power front disc/rear drum brakes on my 69 GTO 400 TH 4 bbl convert.
The discs and drums have been redone recently but they still react like manual brakes - they do stop me but it takes quite an effort on the pedal.

The shop suggested replacing the master cylinder and the booster but also questioned the vacuum level at the booster. I can't find that spec in the Service Manual -does anyone know that number or range? Any other ideas appreciated as well.

Thanks - Rick

[engineer]

vac. at booster is 11 in. min. with a good check valve. Try changing the check valve and see what happens.

[ricks69goat]

Thanks Engineer:

My check valve looks new. I tried blowing thru from carb side to booster side - no luck, but I could suck air thru carb side from booster. It would appear okay.
I think they measured about 12 in. when checking brakes.

[gtohurstjudge]

That is enough vacuum for the booster to work. If you have no
power assist the booster is bad. As long as the master cylinder is not leaking
fluid out the back, there is no need to change it, just put a new repro booster
on the car or have yours rebuilt.

[engineer]

agreed, then booster is the problem.

[ricks69goat]

Thanks for the help evryone. Just my luck the replacement booster is on sale this month if I get it tomorrow.