Thread: Vacuum for Power Brakes!

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One more question.. what is the distance from the pivot of the brake pedal mounting to the connection of the master cylinder rod and what is the total length of the pedal lever? From the center of the pad to the center of the pivot mount..

The 10 inch of vacuum is a thorn for sure but maybe you can change the master cylinder rod connection and "pick-up" some mechanical advantage / leverage and it will only cost you some labor. If you have the room, you might also add length to the brake pedal..??..?? Even an inch will add to or increase "clamping pressure" of the calipers.

6 to 1 ratio.

Originally Posted by curmudgeon

6 to 1 ratio.

Should work fine



pedalrati.pdf

Originally Posted by curmudgeon

6 to 1 ratio.

Any way (room?) to increase this?

Not knowing what intake your running, I would move the vacuum hose for the brake booster to the connection now plugged under the carb. It probably won't change anything but it may increase the speed the 10 inches is acquired. You may be connected to a single runner now and being under the carb may increase the vacuum pulses. Probably not enough to really notice but it won't hurt to try.

It seems you know the answers to the questions readily so should I/We assume you've been dealing with this for a while?

You have a couple choices I'm thinking.
1. increase the brake pedal ratio as much as you can.
2. replace the booster with a wider unit if possible,
3. install a vacuum pump to increase vacuum "pressure"...

The larger pedal ratio will increase system pressure by using more leverage against the master. The wider diameter booster will apply more force when compared to your current booster. And the vacuum pump will also increase system pressure by increasing the force applied inside the booster. I think options 1 and 3 are the most effective, but not knowing your car, it's a swag for sure.

Do you or have you tested brake system pressures? If you could install a gauge and record system pressures front & rear as a starting point. then when you make a change, you can re-test and verify if your changes are having a positive effect!

Great idea!

I thank all of you for your ideas! The truck is presently at a friend's house having an
oak roof structure built for it. As soon as I get it back I will get after it with a vacuum gauge, relocate my vacuum takeoff at the carb base and go from there.
I will keep you posted as I sort this out and let you know what I find!
Thanks! Joe