Excessive pedal travel on rebuilt S callipers, but car stops fine Options

[phillstek]

Just finished rebuilding the front callipers with new pistons and seals. Bled them 3 times including power bleeding but the pedal just won't come up. It feels like half the available pedal travel is in free motion before the brakes engage.

Car stops without pulling or locking up and the pedal pressure holds when stomping on them but I would prefer to have the pedal engage pretty much as soon as I hit them.

Any suggestions on possible cause and what I need to do to fix it?

Thanks

[THE STIG]

I just ran into the exact problem, went from a Brembo 4 piston to 911S calipers on my Vintage Race Car. No rebuild on the S caliper, but exact same problem. Pedal with the Brembos was rock hard and immiediate. Switched to the S calipers, had to adjust brake plunger inward to get the same pressure point for heel/toe purpose, and now have to bleed the brakes after every 30 minutes session. They get bad. Have brake cooling as well, so I know its not OVER heating. I know the previous owner installed stainless steel pistons, and car was for AX use only. Rarley had to bleed them with the Brembos. Maybe after a test, qualify and race, they would need to be bled. They do stop the car, stops straight, but why the pedal feels different is a mystery. Its possible that the known flex in the caliper body is the cause of this, but you can feel it sitting in the car, stopped with no pressure applied. Pedal travel increased because of a caliper makes no sense. I also experienced great difficulty with bleeding the 911S caliper. Fluid runs air free while bleeding, but they just never feel good. Most folks say that is just they way thay are. What I do know for sure, is that I could run anything else on my car, I would.

THE STIG