a4944

I can back up Waterguy about an 86 944 Turbo. I have the 5/33 and I'm using PF97s front and rear. I've already flatspotted one rear tire and then locked the rear up again the very next event but did not flatspot. I also sometimes get wandering under hard braking, I used to have Poterfields R4s in the back and did not have this problem. I'm going back to the stock valve.

Mark

Oddjob

I have not had the rear lockup problem using the 5/33 bar valve on my 87T (same brakes as the 86), but the car has pretty stiff suspension, so it wont be unloading the rear as much when braking hard.

Have used the 5/33 with TS cars/brakes, and have thought about trying a 45bar valve to get even more rear brake to match the front increase due to the 928S4 front calipers. I do know that a 55bar is too much and will cause rear lockup.

KLR

I would say that the stiffness of the suspension is a big determinant here. If you are on stock springs, additional rear brake bias (via proportioning valve or different pads) will frequently feel unstable. This is particularly true when braking on a downhill or a surface where the track "falls away" to one side. The braking zone before turn 5 at Road America is a perfect example.