Well I recently installed a S5 TII BMC in my FB because I happened to have one lying around and the stocker had **** the bed on me. It feels great on the street but those feels quickly evaporated when I took it to my local track on the 4th.

This was my face in the first braking zone:


Initial bite is god-awful, then after a second or two the pedal drops an inch and it goes into the verge of lockup (im on slicks at this point btw). I got used to it over the course of the day but the current setup is hardly confidence inspiring.

I'm thinking I can help the initial bite by ditching my oatmeal pads and going with some hawk's or the like, it also desperately needs some kind of adjustable proportioning valve as I currently have none and the rears are the first to go.

I suppose my questions are as follows:

• Can any adjustments be made to the booster to improve pedal feel?
• Are there any other boosters available that fit the S5 TII BMC?
• Is this setup worth dumping more money into?

 

Sounds like the booster>MC pushrod isn't adjusted right.

Ditch the whole thing and get the booster/MC from a Subaru Legacy (1 1/16") or an Acura Integra (1") as a combo from the junkyard.
The Subaru is easiest as it already has the 10mm input shaft to match the Mazda clevis. It's a direct swap, requiring just a bit of fiddling with the brake lines.

 

Clokker : What year legacy and what year integra?

 

I believe the Subaru was a '97, not sure of the Honda.
I just look at the parts and pay little attention to the car as a whole.

 

What about mastercylinder interchangeability? I'm already 90bucks into the current one, I'd rather not have to go back to square 1 if possible.

 

Physically yes, your MC would bolt on to either the Honda or Subaru booster but that kinda puts you right back to square one if the rod is the problem.

Sorry I'm not more helpful, my yard sells the booster/MC combo for $40 and it's easier for me to just get the whole shebang and not mess with the adjustment.

 

I thought the Subaru boosters and the like we're only compatible with non-s5 tii BMCs .

FD and 929 boosters are both compatible. But you need to set the plunger depth for those too... I would start with checking that.

 

FD, 929 and Subie boosters all have identical bolt patterns (on either side).
Some Hondas and many Nissans do, too.

 

Before you go to all that trouble why dont you take yours apart and measure the rod clearance to see if its right. A simple adjustment may cure the problem. The FSM tells the proper clearance of the rod.