Jeff, A 965 has the correct 28mm rotors in the back. They don't fit on a n/a 964.

 

Geoffrey is using the 993 RS set up, same as on my 993(large front/medium rear). Lots of the 993 guys use this, as on those cars it is a bolt on.

Geoffrey had to jump through some hoops to get it to work on his 964, i.e give up the parking brake, not a big deal on a track car but a no no for the street.

The 993RS set up is 322x32 front as used on the 965 fronts and 322x28 rear.

I have both the 993tt and 993RS rear calipers, all the tts I gave ever seen where 28/28 but as VB stated I have spoken w/ people that aver that theirs are 28/30. The RS are 30/36 and give more rear bias. In its stock condition I prefer the RS rear over the tt, but suspension and diff(LSD) changes may warrant the tt. We'll see.

 

Oh and lost in all of this is the m/c question, the 993 or even better the 993tt m/c would make a vast improvement in pedal feel.

I believe that Geoffrey did the right thing and t/p'ed a full hydraulic boost set up from an RS into his car. The 25mm m/c is best but a 993 23.8 is also very good. The stock 20.6 used on a 964 is barely adequate. I would very much like to do the same, the ABS shutoff alone can be a lifesaver

I disagree w/ Bob G. it seems a shame to spend a lot of $ to machine the 965s down when the 993s are perfect(except for color) to start w/

 

One last thought Race Technology has modified 993tt rear rotors to fit 911s and retain the parking brake.

They also had a kit for the 964 which used the 965rear caliper. You might want to give them a call to see if the 28x299 rotors w/ parking brake are available separately.

 

Adrian's book (pg. 246-247) lists the stock m/c for a C2 as 20.64 while a stock C4 has the same 23.81 m/c as the Carerra RS and Turbo (965).

This would suggest that a m/c change on a C4 is not required, yes?

Marc

 

Correct the hyd boosted 964C4 and 965 used the 23.8mm m/c, same size as the 993. This is good but....

the larger hyd. boosted 25.4 mm m/c used on the 964RS(ROW), 993RS, 993tt, 993 C4 and 993C4S is better for the 36/44 and 30/34 or 30/36 caliper systems

 

As usual, Bill is right on. Larger m/c also will give a better feel to the brakes as a whole. On my list of things to do. Boy that list is growing faster than I can check them off..

 

Get a second mortgage ready for the 25.4" master cylinder.

The Boost Ratio in the hydraulic booster for the Euro RS is less for an even harder pedal.

Last time I checked, the parts were over $2000 if you want both parts.

The parts only fit cars with the electrohydraulic boost system.

 

FWIW, I haven't changed out my factory MC as of yet. I have emailed back and forth a few times with Bill G. regarding his 993 MC update - seems like it was a pain in the ying, but worth it.

I have had BIG Reds for about 3 years now, maybe more...and have never had a problem with the pedal. DO you think I'll have issues now that I will have the 965 rears?

BTW, I went ahead and installed the 965 rear calipers last night, along with my "new" trailing arms with ERP monoballs, the main bushing and the camberplate ("springplates) - what a nice and convenient way to adjust toe vice having to fool around with both eccentrics!

I had to place about a 2mm spacer (read as washer) between the caliper and the trailing arm to center the caliper - thanks to Bill G. I had been pre-warned. I really don't see an issue with the 2mm a side width in relation to a 24mm rotor when compared to what you should use with these calipers...a 28mm rotor - look at a metric ruler, find 2mm...it's ridiculous to think this could cause issues, really.

Not to knock the nay-sayers, but consider 2mm...then pop out one of your caliper pistons (it's easy to do) - that seal is far from being popped out with the pistons extended all the way out to the rotors, minus the thickness of the brake pad backing plates...not skeered.

 

I agree wiht you Jeff. I'm totally pleased with the same setup.

 

Jeff,

I have installed and sold a 993 MC kit for the 964. It was not that complicated. The issues are 1) the nut size on the brake lines are the wrong size at the master cylinder. answer - get an adaptor (about $5 each) or rebend a new brake line to the front firewall 2) You need the vacuum canister from the 993. This does not mate with the aluminum mounting frame for the bell crank. (there is a part of the frame for the cylinder that goes inside the aluminum part. In the 964 this is tapered. on the 993 it is squared off) Solution, use the 993 aluminum mount or just mill some of the aluminum off the inside of the 964 one.

That was about it. Pretty simple actually. Tom W has this on his car (his was my test mule)... Works great for the Big Reds...

 

JeffI

If you have any completely worn brake pads or metal material the thickness of the pad's backing plate, could you install it in the rear caliper and press on the brake pedal to see if there really is any issue with the thin disc and the 965 calipers.

I think what you say makes sense, it would be nice to prove there is no problem just for the record.