964 Track folks: Brake bias question

[jpachard]

Hello All, I have a 1993 C2 with stock brakes and wanted to know what folks have done, if anything, about the brake bias. I'm running PFC 97 compound pads all around and feel like I could dial a bit more bias to the rear. The car has a factory LSD and otherwise I'm very happy with the braking performance so far. I know on my 1987 911 I just took out the proportioning valve.

What is the typical setup for a 964? What did the 964 Cup Cars run?

Thanks in advance, James

[Bill Verburg]

Originally Posted by jpachard

Hello All, I have a 1993 C2 with stock brakes and wanted to know what folks have done, if anything, about the brake bias. I'm running PFC 97 compound pads all around and feel like I could dial a bit more bias to the rear. The car has a factory LSD and otherwise I'm very happy with the braking performance so far. I know on my 1987 911 I just took out the proportioning valve.

What is the typical setup for a 964? What did the 964 Cup Cars run?

Thanks in advance, James

the Cups and RS ran a 36/44 front, pad area 125cm^2 per caliper and 30/34 rear caliper, pad area 86cm^2 per caliper, the front was a version of the 993 front and the rear is a 993 rear, rotors were 322x32 & 299x24

RS ran a 55bar p/v Cup eliminated the p/v, hyd bias is 1.572 further moved forward by the rotor differential

stock 964 runs a 36/40, front pad area 86cm^2 per caliper and 28/30 rear caliper, pad area 86cm^2 per caliper both front and rear are versions of the RS/Cup rear. rotors are 298x28 & 299x24. p/v is 55 bar. hyd bias is 1.72 and unmodified by rotor differential.

you can safely remove or gut the p/v, further bias modification will have to be from differential pad choice f/r or using bigger rotor/caliper combo in front

[jpachard]

Bill, thanks for the information. Do you have a p/n for the front rotors/calipers for the Cup setup?

Cheers, James

[Bill Verburg]

Originally Posted by jpachard

Bill, thanks for the information. Do you have a p/n for the front rotors/calipers for the Cup setup?

Cheers, James

965.351.043.00 32x322 1 piece rotor /L
965.351.044.00 32x322 1 piece rotor /R
965.351.423.01 caliper /L
965.351.423.01 caliper /R


you also need 993 rear calipers, but can keep the stock rear rotors


there are better though probably not cheaper ways to do it

[Tom W]

Since you don't have any significant issues with the current set-up but are simply thinking a bit more 'bite' in the rear could help, the easiest and cheapest would be to simply try different rear pads that give the extra 'bite'. In the past, I ran Pagid Yellow up front and the Black in the back to accomplish that.

[jpachard]

Hello All, thanks again for the help. Yes, I'm going to gut the p/v and then source some of the front calipers since I'm trying to make the car an exact replica.

Bill, Can I run the updated front calipers with my current stock calipers and do these front calipers bolt on directly or do I need any other hardware?

Cheers, James

[johnsjmc]

I have a new to me 95 993 C2 with ABD/LSD.(4 ch. ABS) It has PSS 9 suspension.I have a similar issue . I would like a bit more rear bias. On hard braking the fronts activate the ABS. Bill V. What F/R ratio have I got and how much will it change if I gut or eliminate the 2 PVs?

[Bill Verburg]

Originally Posted by johnsjmc

I have a new to me 95 993 C2 with ABD/LSD.(4 ch. ABS) It has PSS 9 suspension.I have a similar issue . I would like a bit more rear bias. On hard braking the fronts activate the ABS. Bill V. What F/R ratio have I got and how much will it change if I gut or eliminate the 2 PVs?

Stock 993 has 1.572 hyd. bias and there is a tiny move to the front because of the rotors(304 vs 299), you could remove or gut both p/v(there is one on each rear circuit). I'd try differential pads first, ex, Pagid yellow(19 or 29) front and black(14) rear.

On my 993 I have 993RS brakes, hyd bias is 1.472, w/ no additional move to the front because the f/r rotors are the same diameter(322), I use Pagid yellow all around and never get into the ABS. A friend has the same setup w/ Pagid black all around and does get into the ABS, he's probably driving a lot harder than me.

I really like the 993RS bias(when the car is set up for it), rotor temps are close to even f/r, this is not the case w/ any other 911/996/997/Cayman/Boxster that I have ever monitored

[jpachard]

Bill, Do you have a p/n for the rear calipers for the Cup setup?

Also, I assume both front and rear are a bolt on replacement?

Thanks, James

[Bill Verburg]

Originally Posted by jpachard

Bill, Do you have a p/n for the rear calipers for the Cup setup?

Also, I assume both front and rear are a bolt on replacement?

Thanks, James

yes, but the 993 n/a rear is the same w/ a different part #
993.352.421(2).00 993 n/a rear
964.352.421(2).70 964RS/Cup rear

rears are a bolt on w/ stock or 968M030 rear rotors

fronts are a bolt on to 965 and 964RS uprights(or 993 & 993RS uprights) and are a bolt on w/ an appropriate adapter to stock 964 uprights w/ an appropriate 322x32mm rotor.
964RS/t and 993RS/tt work but have different o/s and need to be used a system, ie all 964 or all 993

[jpachard]

Cool, thanks Bill. Are the adapters to mount the front cup calipers to the 964 upright commercially available or are they just a spacer that brings the caliper out to accept the larger rotor?

Thanks in advance.

James

[jpachard]

Once more thing, my rear calipers are the 4 pot design since I have a 1993. looking at the p/n's it looks like these are the same as the ones used on the cup cars. Is this correct?

Thanks again and sorry for all the questions.

James

[Bill Verburg]

Originally Posted by jpachard

Cool, thanks Bill. Are the adapters to mount the front cup calipers to the 964 upright commercially available or are they just a spacer that brings the caliper out to accept the larger rotor?

Thanks in advance.

James

Yes, VCI has them w/ the correct o/s for either 965 or 993tt front rotors, If I were going that route I'd want to use 993tt 2 piece over 964RS/t 1 piece rotors, there are actually several aftermarket sources for non drilled 993 322s too.

[Bill Verburg]

Originally Posted by jpachard

Once more thing, my rear calipers are the 4 pot design since I have a 1993. looking at the p/n's it looks like these are the same as the ones used on the cup cars. Is this correct?

Thanks again and sorry for all the questions.

James

It's the same caliper but 993 rear has 30/34 pistons, as did 964RS/Cup. 964 uses 28/30 pistons and 965 used a different wider version w/ 30/34 but also w/ a different o/s that is incompatible w/ other 964 rotors

for use w/ the big fronts you want the 993 rears

[jpachard]

Bill, What is the difference between the 1993 turbo look rotors p/n 965.351.043(4).00 and the turbo 3.6 rotors, p/n 965.351.045(6).00. I have purchased a set of the calipers you referenced in post # 4. It also looks like I might be able to use the 928 GTS rotors which are solid, thoughts and if they work do you happen to have a p/n for the 928 rotors?

Thanks again for all the help.

Thanks, James

[Bill Verburg]

Originally Posted by jpachard

Bill, What is the difference between the 1993 turbo look rotors p/n 965.351.043(4).00 and the turbo 3.6 rotors, p/n 965.351.045(6).00. I have purchased a set of the calipers you referenced in post # 4. It also looks like I might be able to use the 928 GTS rotors which are solid, thoughts and if they work do you happen to have a p/n for the 928 rotors?

Thanks again for all the help.

Thanks, James

I'm not sure, all 3 of those rotors should work, they are all 964 o/s 322x32.

I'll have to look the 928 # up when I get home, Sun.

[jpachard]

Great, thanks Bill. I know Manny Alban runs the 928GTS rotors so I might just run those if I can find them for a good price.

Happy Thanksgiving!! James

[Bill Verburg]

Originally Posted by jpachard

Great, thanks Bill. I know Manny Alban runs the 928GTS rotors so I might just run those if I can find them for a good price.

Happy Thanksgiving!! James

james, sorry I don't have the 928GTS rotor part #s, all that info was in a separate place from the normal PET, Wayne doesn't have them listed here either.