Soft Brake Pedal Issues

[rattytat]

All

i have 930 calipers fitted to a competition car. *Balance pedal box fitted so able to balance between front and rear brakes. *Two separate circuits (front and rear) and racing brake fluid, brakes bled several times - no air in the system and no fluid leaks. *Brake pedal goes well down and is soft - pedal effort doesn’t change even when pumped…. Nothing like the brakes on the road going 930. *What am I missing - any thoughts?? Thanks, Dave*

[nickelplated5s]

What about your pedal bushings?

[callard]

You still have air bubbles in the system.

[dannobee]

Did you bench bleed the master cylinders before installation?

[rattytat]

Originally Posted by dannobee

Did you bench bleed the master cylinders before installation?

I’m not sure, I’ll check…

[steven c]

Get the Motive pressure bleeder and be done with guessing whether there is air in the system or not. Pick the right adapter here:

https://www.motiveproducts.com/collections/adapters-1

Or use a Mity-Vac and suck the air out but a much slower process.

[EC900]

How old are the rubber brake hoses. Maybe one failed?

[David Inc.]

Originally Posted by steven c

Get the Motive pressure bleeder and be done with guessing whether there is air in the system or not. Pick the right adapter here:

https://www.motiveproducts.com/collections/adapters-1

Or use a Mity-Vac and suck the air out but a much slower process.

I tried something different last time because too much had bled out of the system while I had the brakes off for rebuild over the winter. I ran a hose from the bleeder all the way back to the master and pumped, and pumped, and pumped, and pumped. I went through a couple of rotations for each wheel and it really made a difference. It used a lot of extra fluid to fill the hose, though, which just goes to waste.

I have a motive but I don't like using it on the 911, and the mityvac wasn't quite cutting it for whatever reason this time.

[Alan L]

Either air still in there, or - you are using rubber hoses - which I doubt on a race car.
Braided lines, right?
In which case - air.
Alan