Brakes / Spring Rates - Brad? Racers? Options

[Evill Ed]

Hey, I just finished installing BMW 320i calipers on the rear of the 914. I added a Tilton proportioning valve too. In the front, I have vented 911 rotors with M style calipers. They are actually BMW units, not 320i, for a 5 series with vented rotors. The Pistons are a little larger than M pistons.

Anyway here is the deal. My front brakes lock up way before the rears. When braking moderately, with the propotioning valve set in position 5 (of 7) the car pulls down tightly and evenly. If I brake hard, the car starts to slow evenly, but then the fronts lock and skid. If I go to max position on the proportioning valve, when I brake heavy at higher speed, the rear gets light and the nose starts to turn to the right. then the fronts lock.

The right front locks faster than the left. The fronts have always locked like this. I figured the stock rear 914 calipers were too small and kinda beat, even with rebuilds, so I went for the 320i's.

The 911 19mm master is new, the brake lines are new rubber, all calipers are rebuilt and perfect, and the system is bled well.

I'm begining to think this may be related to weight transfer from front to rear.

The front is 21mm torsion bars with a 19mm Weltmeister sway bar with Weltmeister soft bushings.

The rear is 140# Weltmeister springs. Front and rear struts are Bilstein.

Should I go to 165 or 180# rear springs?

Am I on the right path?

I appreciate any input.

Regards,
Ed