Brake Upgrade

[enolam]

OK, I'v had so many different answers to this that I'd really appreciate the input from someone who has first hand knowledge. What does it take to put 964 front calipers on the rear of a 77 911s narrow body?? PLEASE!

[RallyJon]

To put front calipers on the rear? A death wish?

[enolam]

I have big reds for the front to replace the 964's that I like to move to the rear.

[RallyJon]

OK, but 40/36 pistons are still way too large for the rear. Unless maybe you're running the big reds with custom 380mm rotors or something.

[enolam]

Are they bigger than stock big red rears?
Actually, I had a 77 930 with big reds on the front and 928s4 calipers in the rear and it was great.

[RallyJon]

The difference is the piston sizes. The 964 front and rear calipers look the same externally, but the fronts have much bigger pistons. See Bill V's tables here:

http://www.pelicanparts.com/MotorCity/wmv/brakes.htm

[Bill Verburg]

Best choice to match Big Red fronts on 322mm rotors is 993RS rears on 322mm rotors

From the left, 993ttrear, 993RS rear, 993tt front aka Big Red


You could also use a 993tt rear the machining will be the same. A 993RS and 993tt rear are the same caliper except for piston size. The middle caliper above is an RS rear that has had the axial mounting ears machined off then drilled and tapped to accept an axial adapter similer to that used on the front. The 993tt rear rotors need to have a 911 parking brake pinned into them




Another thoough poorere choise is a 993rear or beter a late 965rear on a 930 309mm rear rotor as pictured here



Details here

[enolam]

But will the 964 fronts, with holes plugged and redrilled, bolt up in the rear with a 930 rotor without interference from the narrow body banana arms?

[Bill Verburg]

Yes, but as has been pointed out, the pistons are too big. You will then want dual masters

The 964 front has bigger pistons and a wider throat than the 964 rear. the wider throat is perfect for the 930 rear rotor

[enolam]

So, to make sure I understand, the issue is that the master cyclinder won't push those big pistons?

[Bill Verburg]

that's part of it, the other part is bias