nwest15

It has been a while since I did this mod, but I'd like to help if I can.

Did you use the STi or the WRX MC (booster is the same)?. The WRX is the 1" and the STi is the 1 1/16". I tried the STi first in my struggle, and it was awful. Like you describe with the rock solid pedal when engine off. Honestly, if you are using the STi MC, my advice is to drop it and get one from a WRX.

Could you describe a little more what it is doing when engine running?

Appreciate the response. I am using an 06 STi BB/MC so the 1 1/16" bore. With the engine running the pedal loses almost all pressure. With the car lifted, the brakes do stop the back wheels at the very bottom of the pedal travel. The pedal feels monumentally worse than stock LGT setup (or any car with properly functioning brakes), but it doesn't feel like the pedal is disconnected or sinking into the floor or anything.

There are no apparent leaks anywhere, fluid level stays constant in the reservoir, no puddles or wet spots. Put about 2L of brake fluid through the system and getting clear fluid with no air bubbles in any of the lines.

This whole job has been a pain in the ass every step of the way so it has me second guessing if I messed something up along the way. It's possible that the STi MC will still be too mushy for me after its all working, but this definitely feels like something wrong rather than another poorly performing MC.

My best guess is there is some significant amount of air still trapped in the MC or elsewhere. I probably did not do a fantastic job bench bleeding...

hey all, quick question.

I just went through the whole process for swapping my Booster/MC and got everything put back together, started the engine and the brake pedal has practically no resistance. It does not sink to the floor or move on its own however.

With the engine off after 3-4 presses the pedal is rock solid. I bench bled the new MC, pressure bled all 4 calipers, measured and matched the brake clevis to the old booster, and inserted the check valve (bullet side towards the intake/flat side towards BB and firewall).

kind of at a loss here. If anyone has any ideas, I would appreciate it.