Brakes question...Bill?

[RideShoot&Drink]

I have a front set of S4 calipers with appropriate adaptors and rotors that was on my 78 chassis. My rears are 965 calipers with appropriate adaptors and rotors that was also on my 78 chasis. Is it possible to make it work on my 90 C2? And if yes, which parts can be used from my current setup? Thanks in advance.

[Bill Verburg]

You can use the S4 calipers, you will need new adapters and rotors. 928 S4 rotors would be a good, cheap, bolt on rotor.

the 965 rear caliper unmodified is a bolt on, but modified , no. In any event there is no readily available 28mm rear rotor for the 965 caliper. I would use stock rotors, or 968 sport rear rotors(same size but drilled) and 993 rear calipers.

[RideShoot&Drink]

Bill, would I have to change stock MC, proportional valve on my 90 C2 if I use S4 caliper/rotor in front and 993 caliper/C2 rotor in the rear? Does S4 front rotor bolts on to C2 with no mods? Also, in your opinion, is it a worthy upgrade to consider? I have a set of rear calipers from 92 C2, which will be the cheapest of all. What do you think? Thanks in advance.

[Bill Verburg]

would I have to change stock MC, proportional valve on my 90 C2 if I use S4 caliper/rotor in front and 993 caliper/C2 rotor in the rear?

Only if your car was originally fitted w/ 2 piston rears. If so you will need either a 55bar or 60 bar or adjustable p/v

The S4 front is a lot of brake, you want as much rear brake as you can get, the 993 rear is as good as you can get at a reasonable cost. Personally I would want more but it would involve too many other compromises on a 964.