Hi guys, I'm trying to work out a solution for my brake balance (front - rear) problem. I took the car to an old airfield to do some testing prior to my IVA test on Jan 24th and I can't get the fronts to lock up before the rears. I adjusted the bias bar in the pedal box all the way to maximize front braking and still the rears would lock first.

I think my issue is with the fact that half way through the build I made the decision to go with BMW rear calipers which have park brake motors in them. These are from a 5 series whereas the fronts are 3 series and I suspect the 5 series units will have a larger piston in them to cope with extra weight of a 5 series car.

I'm guessing a proportioning valve is not permissable for IVA so I'm looking for other options... I think one option would be to replace the rear master cylinder with one with a larger bore and hence less pressure?

All suggestions welcomed as I'm running out of time!

Thanks in advance,

Chris

I fitted a brake bias knob when I built mine and got it SVA'd. All I had to do was lock the knob in place once set. It can always be unlocked after nudge nudge!!!! if required.

I had exactly this problem when I fitted a full set of hi spec calipers to my car, in the end I just swapped the front and rear master cylinders around as you say the bigger bore for the rear and this cured my problem. I then just used my brake balance bar to fine tune it.

Thanks for the replies. I think I'll give the bigger bore master cylinder a go and see how I get on.

Chris