Originally Posted by geezer#99 (Post 9306089)

Change your pedal ratio.
Check where your connection pushrod is on the brake pedal and Drill a hole 1 1/2 inches lower. Attack the pushrod there and test. Your pedal ratio should be close to 4 to 1 then.

Originally Posted by Sheepdip (Post 9306181)

Can you post pic's of your brake calipers as you have them installed? I'm just shooting in the dark here....on a thread a while back there was a situation as yours where the owner kept stating the bleeders were on top, and they where.. But they were not on top of the piston bore to remove all the air. He finally rotated or swapped the brackets which put the bleeder actually on top and problem solved.

Originally Posted by MikeB (Post 9306351)

Yes, that should eliminate the master cylinder.

Also, I think the problem is something other than pedal ratio or master cyl bore size. As an example, when I installed 85 C10 spindles and disc brakes on my 69, I actually drove the truck for at least several weeks with its stock manual drum/drum master cylinder, and the brakes worked pretty well. Sometimes I wonder why I went ahead and installed the 71-72 master cylinder, booster, brackets, and pedal linkage! However, the system has worked great since then, minus some issues with the 50+ year old combo valve, and brain fade on my part when bleeding brakes recently.:o

Originally Posted by RichardJ (Post 9306361)

>>I checked the clearance for the push rod from the booster to the MC, and it moves immediately when pedal input is applied, and moves smoothly.<<

That doesn't tell you anything about the correct booster pin length.


>>For S&G I adjusted the pushrod WAY out to preload the brakes, see if I could even stop the trucks rear end while in the air, it took 5+ pedal pumps to stop it, but once stopped it did not allow the wheels to free spin in gear again, as if they were locked on. <<

Adjusting the pedal rod longer just makes a problem with incorrect booster rod worse.

MC pistons must be able to return to seated position so that ports are opened to allow fluid to return to reservoir when pedal is released.

Adjust pedal rod for freeplay.
Adjust booster rod with actual measurements. If you don't have the measuring tool you must be able to move the MC far enough to take measurements.
A - B = C, which is what the tool does.
After "C" is determined, reduce pin height ( C ) by 1/32 to 1/16".

I set the clearance at 1/32 on a new booster for my Vette. After a couple months, I noticed at stop lights with slight grade, the vehicle would no longer roll with brake off. (manual trans) The seats inside the booster had settled with age and spring pressure. The pin had extended past my original setting and was holding the MC slightly engaged. I won't set one that close again.