I put in a Pettit BBK on the front. I'm sure there is no air anywhere. The overall stopping power and heat tolerance has improved dramatically with the new tires and HUGE brake rotors, but the larger calipers make the brakes feel a lot less responsive. I have to really dig in to get the "grab" and it needs to be sharper and have a stiffer pedal feel for track events. It is just taking too long once my foot hits the pedal for that to translate into actual braking.

I'm thinking a 929 MC would be useful.

Pettit said you don't need a brake biasing system with their BBK, but the volume of fluid displaced in the fronts has obviously increased so I'm not so sure that makes sense... If I did get a larger MC to compensate, wouldn't I have over braking on the stock rears?

 

It shouldn't.

The 929 should just move more fluid more quickly, shortening the pedal travel and requireing a bit more leg effort. It shouldn't change your F/R ballance.

 

I agree.

What pads are you running?

 

Pads are HP+ front and rear.

Is there a thread with a 929 install and pics? I searched. Is it a straight up bolt in deal?

I really don't know much about FD brakes YET, does the system pressurize front and back in the same chamber? Or are the front and back separate systems and the MC has 2 chambers?

 

Full write-up:

http://www.negative-camber.org/crispyrx7/929.htm

 

If you have bigger caliper piston area up front (thereby necessitating the bigger MC) but the rears are stock then you've shifted your brake bias forward and you need to get an adjustable prop valve to bring it back in line.

Yes, front brakes do most of the work but your stopping distance is a function of 1) tires and 2) getting the rear brakes to do as much work as they can.

Big rotors are mainly needed for heat capacity to maintain braking performance under continuous duty, not for braking performance itself.

 

bigger brakes in the front should lengthen your stopping distance as the bias has now shifted from 68/32 to 74/26.

in order to not lock up the fronts you will not be using the rears optimally.

a 929 will have no effect on longitudinal bias as Peter states.

i ran just the bigger brakes on the front for a number of years and didn't need the 929 MC. there is nothing wrong w it. it is just a smidge bigger.

in order to move toward balance you will need the RacingBrake rears.

as far as not having bite.... you either are running the wrong pads or you have air in the lines.

use two people and w the bleeder closed really stomp on the pedal alot and hold. crack the valve w foot on pedal and close it. the key is max pressure on the pedal.

good luck,

hc

 

Thanks for the help everyone.. I'm going to bleed them again before this track weekend. And when the time comes, change out the rears to find a closer balance.

-Ian