alexandervdr

I mounted a CSSB kit (new drums all round, new brakes/springs/shoes/lines/etc, new slave cylinders, and dual master cylinder with residual pressure valves, and a power booster. Bleeding was a pita, even using a vacuum system did not work. Appeared (after LOTS of frustrating and failing trials) that one of the bleeders was not closing tight...
Out they went and I installed speed bleeders. That was a dream to work with. Still a 2 person job (one pushing the pedal, the other watching what comes out of the bleeder). I now have a very solid pedal feel. Pedal about 7 inches from the firewall, locks fully with pedal down at 5.5 inches. (after adjusting the shoes with the toothed wheel, before I could floor the pedal). The ASM indicates to keep the pedal at around 5", so I can safely lower the pedal from it's current 7" and still have enough 'headroom' before it bottoms out against the firewall .

Question: once I get vacuum in the power booster, will this influence the 'full brakes' position of the pedal (in my logic it shouldn't)? And is it safer to keep the pedal position somewhat higher that the 5" spec until after some driving has set the brakes?

Frankie the Fink

Its almost a subjective decision. When I added power brakes to the '63 the pedal still sunk too low for me. The shop manual said if it was 1" (!!!) off the floorboard that it was within specs....scary as all hell. A forum member turned me on to a McMasters clevis rod that he'd used to help the problem. My pedal is rock hard, completely depressed and about 3" off the floor board now. Feels MUCH safer. You don't want the pedal so high that you fumble coming off the gas to apply the brakes.

You might drive it a while to let it settle in and then see what you think (I did).

BTW - I love the speed bleeders!

Not sure what you mean about the booster affecting pedal height - one of the operational checks is to turn the engine off and pump the pedal until the vacuum reserve is spent to see where the pedal comes to rest -- then with pedal pressure applied start the engine - the booster should cause the pedal to drop approx 1".

alexandervdr

I mean that when I fully depress the pedal without vacuum , it sits now at 5.5 inches from firewall. Will it go lower once the vacuum is applied (somewhere in the next two weeks when I get the engine to run!)

Frankie the Fink

My guess it would be about 1"...assuming your booster is already installed. Remember with manual brakes the rod goes to the M/C, with power brakes it goes to the booster.
You DO know there are two holes in the brake pedal downrod for the clevis? Right ? The lower hole is for power brakes due to the canted nature of the power M/C-booster set up..

Some adjustment should be provided by the clevis rod. Its easy to do after you get things assembled and the engine running...

alexandervdr

Yes I know about the two holes
In the meantime, you are close to becoming my Personal Corvette Assembly Assistant. thanks

GTOguy

Virtually all vacuum assisted brakes will have a lower pedal with the engine running and vacuum available. About 2" lower than with the engine off and vacuum depleted. They are designed that way. In fact, the standard industry test is to apply the brake with the engine off, and start the engine. If the pedal drops, all is good and it's holding vacuum. A blown vacuum booster will result in a high hard pedal.