Wilwood BBK Piston sizes?

[Fidhle007]

Hey Guys,

I'm reposting this here because I figure it might get a little more traffic...

So I'm finally back in the world of E30s and I'm trying to sort out my brakes. I have a 25mm 540 MC and my own Wilwood setup with 12.75" fr rotors and 12.2" rears. Front calipers are 4-piston Superlites with 1.75" pistons and the rears are Powerlites with 1.25" pistons. I still have a vacuum booster and ABS.

I've bled the crap out of the brakes but under vacuum the pedal goes nearly half way down before it stops. it's firm and not squishy with the engine off. I have no plates on the car yet so I can't road test but I've run it around the parking lot a few times and it stops like crazy and the ABS functions well but still, I have the spongy pedal. The car sat for a year with minimal fluid in the rear circuit so I'm suspect of the MC but I've also been told I have way too much caliper for a 25mm MC to handle.

I'd love some input on what you guys thing before I rip out the ABS and dual MC and boosterless, which is also a possibility. I think I already know what the answer to this will be, but boosterless with ABS is a really bad idea, right?

Thanks!
Brendan

[2002maniac]

Sounds like a bad MC to me.

[Fidhle007]

The Fr and Rr circuits are fluid-connected in the MC, right? So if the rear seal was bad I could just be pushing through that circuit before I hit the front, which would explain the pedal travel at first but the firmness once I hit bottom...?

[xphiledan]

I've got a massive wilwood kit and had the same problem. Bled the brakes multiple times. Swapped out mc. Same problem.

Brought the car to the shop and there was still air in there. They had to rig it to a shop power bleeder for a good number of hours and it fixed my problem.

Good luck to you

[Fidhle007]

I have a shop and a power bleeder... Maybe I'll keep trying once I can road test it a bit!