Help with brake upgrade ideas.
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For the sake of completeness, if you are contemplating a big brake caliper up front on a narrow body 964, using a 993 rear caliper with the existing rotors works great to maintain good brake balance. They are a straight bolt-on application, use the same pads, same rotors. Just hook'em up! I got a set of used ones for $200 a couple years ago...
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Originally Posted by garrett376
For the sake of completeness, if you are contemplating a big brake caliper up front on a narrow body 964, using a 993 rear caliper with the existing rotors works great to maintain good brake balance. They are a straight bolt-on application, use the same pads, same rotors. Just hook'em up! I got a set of used ones for $200 a couple years ago...
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Originally Posted by garrett376
A cheaper alternative that many people don't realize is that you can buy new, from the dealer, Big Black calipers from a 928 for about $600 for both calipers (they were about $247 each 2-3 years ago). Add new, factory 965 rotors for $144 a piece, and some caliper adapters ($300 new, 100 used if you can find some) and you've got a Big Brake setup for about half the price of most kits out there. Get some 993 rear calipers and remove the proportioning valve (or use a 60-bar turbo valve) and you'll have a nicely balanced, super braking car. The calipers aren't red, which I actually prefer 
A DIY if you're handy and have the right tools. My mechanic did the work
I use stock pads at DE and have never had a problem
If i did it over I would have had the calipers painted
Allan
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Garrett great info! Thanks for sharing. However, I have a question. Which 993 rears should be used: C2 or C4? If I remember correctly they are slightly different. In addition, do you have to do anything with MC? My car is C2, and I think C4 MC is different from what I have. Thanks in advance.
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From: New Jersey
Originally Posted by boxsey911
Has anyone replaced C2 2 pot rear calipers with C4 4 pot rears? Is there much benefit to be gained by doing this? And does the bias valve need to be changed when doing it?
When I switched over to the big reds I sold my rears to a local 964 owner who switched out the 2 pot rears for my old 4's. At first he said it felt like no difference but now after a DE event he said he does not have the brake fade that he had before. He used to find his brakes would fade after a day at the Glen now it lasts him almost 3 days before he gets the same fade.
I do not believe he did anything other than bleed the system after he replaced them.
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Originally Posted by rideshootanddrink
Garrett great info! Thanks for sharing. However, I have a question. Which 993 rears should be used: C2 or C4? If I remember correctly they are slightly different. In addition, do you have to do anything with MC? My car is C2, and I think C4 MC is different from what I have. Thanks in advance.
When switching over to big reds up front you want the 993 rear calipers from a 993 C2 with the same piston and pad size as the 964 turbo 34/30mm The 993C4 rear calipers use a smaller piston size of 30/28 similar to those used in the 964 C4 but not the C4 TL. I did not change my MC and find the brakes to be perfect with a stronger pedal feel than my turbo with the same brakes but larger MC.
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From: Philly Area ----- George Washington took a dump in my backyard!
Originally Posted by boxsey911
Has anyone replaced C2 2 pot rear calipers with C4 4 pot rears? Is there much benefit to be gained by doing this? And does the bias valve need to be changed when doing it?
I went to a site that listed brake pad dimensions - that is how I found out Porsche model calipers would fit. Then I just widened my search for used calipers to include those models.
If you switch from 2 to 4 pot rears, you will want to replace the proportioning valve from the stock 2 pot 45 to the 4 pot 55 Bar.
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Originally Posted by rideshootanddrink
Garrett great info! Thanks for sharing. However, I have a question. Which 993 rears should be used: C2 or C4? If I remember correctly they are slightly different. In addition, do you have to do anything with MC? My car is C2, and I think C4 MC is different from what I have. Thanks in advance.
993 n/a C2, C2S rears are the small body&pad 30/34mm piston but want 24mm rotors
993C4 n/a C4 rears are the small body&pad 28/30mm pistons and want 24mm rotors ie they are the same as the 964 C2, RSA, C4 rears
993tt rears are 28/28, large body&pad and want 28mm rotors
993RS rears are 30/36, large body&pad and want 28mm rotors
A C2 w/ the 2piston calipers can profit from fitting any of the 28/30 small body&pad 24mm rotor calipers
A c2 w/ big red front can profit from fitting any of the 30/34 small body&pad 24mm rotor calipers
RS use a 25.4mm electro hydraulic m/c
C4, and turbo all use a 23.8mm electro hydraulic m/c, all of the other 964s use a vacuum boosted 20.64mm m/c
The 993 vacuum boosted m/c is 23.8mm and should be used w/ any combp of 36/44 front and 30/34 rear calipers. The smaller 20.6 may work but the pedal feel is very much improved w/ the bigger m/c
when using stock 36/40 front 28/30 rear the stock 964 20.6 mm m/c is fine.
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Originally Posted by LouZ
So as not to confuse the issue, I replaced my 2 pots with calipers from a 968. Some 944 and 968 calipers are identical to the 964's. The C4 caliper is the same 4pot to which we are referring.
I went to a site that listed brake pad dimensions - that is how I found out Porsche model calipers would fit. Then I just widened my search for used calipers to include those models.
If you switch from 2 to 4 pot rears, you will want to replace the proportioning valve from the stock 2 pot 45 to the 4 pot 55 Bar.
I went to a site that listed brake pad dimensions - that is how I found out Porsche model calipers would fit. Then I just widened my search for used calipers to include those models.
If you switch from 2 to 4 pot rears, you will want to replace the proportioning valve from the stock 2 pot 45 to the 4 pot 55 Bar.
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Originally Posted by Bill Verburg
964 C2, RSA and C4 rears are identical small body&pad 28/30 for 24mm rotors, RS and 964 turbo are the same small body&pad, but have 30/34 pistons and want 28mm rotors.
993 n/a C2, C2S rears are the small body&pad 30/34mm piston but want 24mm rotors
993C4 n/a C4 rears are the small body&pad 28/30mm pistons and want 24mm rotors ie they are the same as the 964 C2, RSA, C4 rears
993tt rears are 28/28, large body&pad and want 28mm rotors
993RS rears are 30/36, large body&pad and want 28mm rotors
A C2 w/ the 2piston calipers can profit from fitting any of the 28/30 small body&pad 24mm rotor calipers
A c2 w/ big red front can profit from fitting any of the 30/34 small body&pad 24mm rotor calipers
RS use a 25.4mm electro hydraulic m/c
C4, and turbo all use a 23.8mm electro hydraulic m/c, all of the other 964s use a vacuum boosted 20.64mm m/c
The 993 vacuum boosted m/c is 23.8mm and should be used w/ any combp of 36/44 front and 30/34 rear calipers. The smaller 20.6 may work but the pedal feel is very much improved w/ the bigger m/c
when using stock 36/40 front 28/30 rear the stock 964 20.6 mm m/c is fine.
993 n/a C2, C2S rears are the small body&pad 30/34mm piston but want 24mm rotors
993C4 n/a C4 rears are the small body&pad 28/30mm pistons and want 24mm rotors ie they are the same as the 964 C2, RSA, C4 rears
993tt rears are 28/28, large body&pad and want 28mm rotors
993RS rears are 30/36, large body&pad and want 28mm rotors
A C2 w/ the 2piston calipers can profit from fitting any of the 28/30 small body&pad 24mm rotor calipers
A c2 w/ big red front can profit from fitting any of the 30/34 small body&pad 24mm rotor calipers
RS use a 25.4mm electro hydraulic m/c
C4, and turbo all use a 23.8mm electro hydraulic m/c, all of the other 964s use a vacuum boosted 20.64mm m/c
The 993 vacuum boosted m/c is 23.8mm and should be used w/ any combp of 36/44 front and 30/34 rear calipers. The smaller 20.6 may work but the pedal feel is very much improved w/ the bigger m/c
when using stock 36/40 front 28/30 rear the stock 964 20.6 mm m/c is fine.
So reading between your lines, there would be no point me putting 993 30/34 calipers (e.g. 993 C2) on the rear unless I uprate to big reds or blacks on the front. If I keep stock fronts then look for 28/30 rears (964 C4 or 993 C4) as an improvement over the standard C2 2 pots.
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Originally Posted by boxsey911
Bill this is all great information for me.
So reading between your lines, there would be no point me putting 993 30/34 calipers (e.g. 993 C2) on the rear unless I uprate to big reds or blacks on the front. If I keep stock fronts then look for 28/30 rears (964 C4 or 993 C4) as an improvement over the standard C2 2 pots.
So reading between your lines, there would be no point me putting 993 30/34 calipers (e.g. 993 C2) on the rear unless I uprate to big reds or blacks on the front. If I keep stock fronts then look for 28/30 rears (964 C4 or 993 C4) as an improvement over the standard C2 2 pots.
Driver preference is one issue and other factors w/ regard to the car setup.
It's not something the factory ever did but on a 964, which all had much more front bias, but is going to have bias similar to a 993RS which I like very much.
Remember ride height, suspension and lsd are all going to affect the net result
JMPO a low car w/ much stiffer than stock supension and at least 40% lsd would benefit in most cases.
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Were the 993 C4 calipers originally painted silver? The reason I ask is I've found some that are described as coming from a C4S yet appear to be in an original silver paint. Apparently the part number on one of them is 20 4672 00