For those with Big Brake Kits. Master Cylinder Replacement?
 

I just installed a front set of 06-07 WRX 4-pot brake calipers with DBA rotors, Hawk Pads, and SS lines. Pedal feel is great but it engages lower than it did before. I had done a good amount of research and knew this would happen because I am pushing more fluid through the calipers before the brakes actually start to bite.

My question is what are the big brake kits out there doing to compensate for this? After a bit of research it seems that one way to fix this is to get a larger master cylinder but I am only seeing people who have done this on other cars. Is there another solution out there, or are there any upgraded Master Cylinders for our car? ( I have not seen any)

Also if that is the way to go does anyone know if there are any other Subaru models with better master cylinders? I would assume STI's would have a larger bore diameter one, but does anyone know for sure which cars I could get one from that might fit? I'm willing to try some different ones would just like someone with more knowledge to point me in the right direction.

We haven't had any problems with our BBK (AP Racing Sprint)

Are you sure it's bled properly and the fluid level is at the same level as before?

Yes you have more pistons now, but each piston is smaller so the volume should be very close to stock.

Im going to bleed them again tomorrow and see if that helps. Did a two man bleed, and everything went fine, gonna do a gravity bleed tomorrow and see what happens.

Most of the aftermarket BBKs are designed to work with the exicting mastercylinder. By swapping the brakes off another vehicle there is a good chance they were designed for a different size mastercylinder and possibly brake bias. I doubt enough people have done this swap yet to know. You may have to do some measurements and research of your own. If you do, let the community know :thumbsup:

You should be good after you bleed again. On my old car i put some 6 piston Baer calipers on. I had to bleed them three times before the pedal felt right again, lol

There are a handful of members with this swap already (STI BBK swap) all very successful with no need to mod or get a better or bigger master cylinder. No performance issues/brake issues. Just bleed your brakes again OP

I stand corrected. Apologies OP.

I'm running Subaru 4 pots and no issues like this. Go to autozone and spend $8 on the "one man brake bleeder kit"

I run the StopTech 328 kit and have loved them since day one, great quality.

I installed Russell Speed Bleeders in each caliper, awesome investment, single handed bleeding any time.

This is a product that might interest you

http://www.chasebays.com/product/sci...ter-eliminator

This is actually the 06-07 WRX 4 pistons, not Brembo/STi.

Re-bled them this am and now everything feels great.