964 Brakes
Is there a difference between the calipers on a 1991 C4 and an RSA? Can I use the RSA calipers on a C4 or do I need to start replacing rotors and pads, etc.? Would it be better to upgrade to a 993 brake set up? The car is a daily (some spirited canyons) and sees ZERO track time. I have read the posts and am getting confused about size and bias so simple guidance would be greatly appreciated.
Thanks! |
Originally Posted by greenr
(Post 15622869)
Is there a difference between the calipers on a 1991 C4 and an RSA? Can I use the RSA calipers on a C4 or do I need to start replacing rotors and pads, etc.? Would it be better to upgrade to a 993 brake set up? The car is a daily (some spirited canyons) and sees ZERO track time. I have read the posts and am getting confused about size and bias so simple guidance would be greatly appreciated.
Thanks! A C4 will have the same brakes front and rear as an RSA 4 piston front and 4 piston rear on 298x28 front and 299x24 rear rotors, pads for the these are the same as was used on 930s(front & rear pads are the same) The main reasons to change the brakes are 1) better thermal performance for track use - if you aren't boiling the fluid then you don't need more brake 2) looks - this is personal stock a C4 has a 23.8 mm m/c w/ electro hydraulic boost, pedal ratio is ~34.7 which is good, For sporting use 30 would be better, but still better than the RSA w/ ~46.2 stock torque bias is 1.889/ 3.498 below /above the p/v knee, both are front biased, this is safe. thru '83 all 911 bias was 1.491 w/ a 35.3 peal ratio for boosted and 41.3 for non boosted cars. 993 calipers can be used in front use the black 993 caliper w/ a 928S4 304x32mm rotor + an aftermarket caliper adaptor, or change to 993 wheel carriers w/o a caliper adapter(bolt on) in back use a 993 black 4 piston caliper w/ the stock rotor. If you want holes in the rotors there are other more expensive options w/ the 993 calipers bias is 1.659/3.071 still front biased but not as much as stock A bigger set is either 993 or 993RS calipers on 322x32 rotors the rotors here are 928GTS w/ either caliper and a caliper adapter again for holey rotors there are other ways to go unfortunately the 964 hasn't got a bigger rear option w/o giving up the parking brake so bias w/ the 322 front and 299 rear rotors is 1.659/3.071 or 1.713/3.171 depending on which caliper is used an option for a better pedal on a C4 is to use the 964RS 25.4mm m/c |
Do you write that every time you post it Bill? Or do you cut and paste? :)
I really appreciate your through responses to brake questions. Thanks for continuing to post them. |
Originally Posted by greenr
Is there a difference between the calipers on a 1991 C4 and an RSA? Can I use the RSA calipers on a C4 or do I need to start replacing rotors and pads, etc.? Would it be better to upgrade to a 993 brake set up? The car is a daily (some spirited canyons) and sees ZERO track time. I have read the posts and am getting confused about size and bias so simple guidance would be greatly appreciated.
Thanks! |
I run the very early 90 C2 calipers and I have run them pretty hard in the canyons without an issue. They do get a little noisy when I push them really hard but no loss of performance, as noted these cars were built for it. |
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