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interessting topic, and also in my suggestions for my blue track car for the upcomming updates:
I have the 322mm Discs with 964 RS calipers since some years mounted. As i track the car a lot and as the car was transformend (from a heavy C4 to a quite lightweight C2 over the years) quite massive, i have to rethink the brake-situation.
The brake power was/is quite brutal and for my tracks (mostly nordschleife) i do not need the brake power at all and are far away from having an issue with the brakes... current weight of the car with full cage is roughly 1180kg (at Manthey scales with the adaptors instead of the wheels it was 1146, lost in between roughly 30 additional kg. Weight of an adaptor is 10kg, so i have to add 50kg to compensate the wheels instead the adaptors...)...
At the moment, i am in the process of removing the last kg from the car. I get carbon fenders, bumpers, doors, remove the sunroof and add plastic windows... so i expect a reduction of 65 to 80kg from that over all... What i think about is, to fit smaller 993 304 brakes... Sames pad as the 964 RS caliper (and i have a lot race-pads in my storage i would like to use further...), also same thickness of the disc with 34mm.. but mass reduction of 2kg per disc...
as the 304 disc with the 993 caliper at the 964 wheel carrier with the epytec adaptor would just work with the (expensive) 928 S4 disc, i would also upgrade my wheel carrier from 964 stock to 993 alloy parts (no RS - normal carrieres), which saves another 2kg per side... - so roughly 8 - 10kg reduction at the front axle...
Question - as this is a brake thread - is: does the 993 brake with OEM discs and hot pads also work perfectly for track purpose, as the 964 RS setup does? And - as i removed the brake bias valve completely some years ago - what to do with the valve to prevent overbraking the rear but have maximum braking power at the rear (which i think/feel, the rear is very important for good braking performance and braking stability...) at the other hand?!
Suggestions? Worth the effort?
Another advantage would be the cheapness of the 993 front discs :-)
993 vs 964RS
these are very similar but the bigger front rotors on a 964RS increase the thermal envelope and increase front bias, removing the p/v helps but its still a relatively front biased system.
993RS front has a tad less front brake torque due to slightly larger effective rotor radius and much more rear brake torque due to larger pistons and larger rear rotor, This is around the limit of useable rear brake and it helps to have an effective lsd, low ride height and stiff suspension to fully utilize it.
The amount of rear that can be used depends on many things, The factory uses p/v's to err on the side of safety w/ stock wheels, tires, suspension etc. It also depends on road conditions and the dynamic state which exits at a particular time, The problem w/ p/v is lag, in that things can change more quickly than the p/v effects on the brake system can take place. This is one reason that from 993 on Porsche uses larger brake lines as these reduce that lag a bit.
On a true race car dual parallel masters w/ a balance bar for fine tuning are the ultimate solution
I actually have considered this as well but the weight penalty with the front brembo 332x32 rotor was negligible and actual weight loss in the rear -so I went that direction.
What do you think about brake power of the 304 setup? Still enough and heat capacity also sufficient?! An other idea was, to fit my 64RS calipers (which are already tüv legalized with 322disc for my car - what in germany is always an issue) at the 993 wheel carriers with 322mm disc brakes. For that, i would need 993TT brake disc front, right?! Perhaps i'll find al lighter disc for that setup and have in the end also some "serious" mass reduction...
Originally Posted by Bill Verburg
993 vs 964RS
these are very similar but the bigger front rotors on a 964RS increase the thermal envelope and increase front bias, removing the p/v helps but its still a relatively front biased system.
993RS front has a tad less front brake torque due to slightly larger effective rotor radius and much more rear brake torque due to larger pistons and larger rear rotor, This is around the limit of useable rear brake and it helps to have an effective lsd, low ride height and stiff suspension to fully utilize it.
The amount of rear that can be used depends on many things, The factory uses p/v's to err on the side of safety w/ stock wheels, tires, suspension etc. It also depends on road conditions and the dynamic state which exits at a particular time, The problem w/ p/v is lag, in that things can change more quickly than the p/v effects on the brake system can take place. This is one reason that from 993 on Porsche uses larger brake lines as these reduce that lag a bit.
On a true race car dual parallel masters w/ a balance bar for fine tuning are the ultimate solution
I took a break for the new year. Hope everyone had a great one!!!
Just to throw these out there and to my surprise weight was not what I expected.
The 992 GTS fronts weigh exactly the same as the big reds both with pads.
94T/993T/RS big red front caliper with pads 992GTS 3 piston front caliper with pads
94 turbo 322mm rotor similar over all to the 993T/RS
350mm girodisc for 992 caliper. a consideration of using 993TT big reds. Same width and offset. 5mm shorter hat than the 94 turbo. Although I am sure a solution can be found for either application.
What surprised me was the rotor weight. I had aluminum hats for my car and the weight savings was nominal. The Girodiscs do save some weight but the 350mm is a considerable increase over the stock rotor. I will see how the RS brakes work with all this hp the Blue meanie will have this might be a consideration if they don't do the job but I think I will be OK. If not I might consider these as an option with a lot more figuring. It will require a creative adapter and the feeds and bleeds will need to be swapped. The design might make it harder to do. The 981 was simple just spacers up front and a direct bolt up. The mounting bolts are roughly 3/8" further apart than the big red.
3 pistons starting with 30, 32 then 34mm. These need to be rebuilt. Although there is no weight savings the increase in pad and pistons is considerable. What rears would be needed is a ?
Down side is you need to remove the caliper every time you change your pads so i am assuming studs should be installed
I have had several inquiries for 993 and 964 kits so thought I would follow up here as it may be of interest to some in light of the thread. Surface Transforms has ceramic kits for these models already for those looking to save weight, improve performance, and eliminate brake dust. We currently have 964 "Restomod" kits for 964 models running the 993 Turbo "Big Reds". If you have a 964 running the 993 Turbo Big Reds, you will run our 993 Turbo front disc, with the 964 rear hat and 993 Turbo annulus (friction ring). Think Singer...
For 993 C4S/Turbo/RS models, we already have the front discs available, and the hats for the rears should be done within the next few weeks. We are currently taking orders for both kits which should be able to ship around March. The only issue currently is that the big reds use the Pagid 1842/1204 pad shapes which don't come in the RSC1 compound. The RS29 compound is available and will be pretty quiet on the street and very low dusting as well when paired with the STs. However, RSC1 is the best all-around pad for street/spirited, or track use. It is noiseless and dustless on the street, but very capable on track as well. They are also longest-lasting in terms of disc wear. That said, assuming many of these cars are street-only/or mostly street-use cars, these discs will last forever on the street with basically any compound. They can also be refurbished if needed if the car is tracked heavily. For those that would want the RSC1 compound, we can get them manufactured, I would just need a commitment of about 10 or so orders to get it done.
Pricing isn't finalized, but estimated all-in pricing with the discs, RS29 pads, shipped, is $15.2K. On February 1st, ST is having a 10% price increase on all kits so the cost will go up to $16.6K. RSC1 pads will add $150-$250 per order most likely.
If anyone is interested, please reach out and I can add you to the list of 993/964 inquiries or to place an order. Let me know if you have any questions.
Rick,
This is great information.
Is there support for the 964 Turbo? I think the hat would need to be different for the 964 Turbo vs 993 Turbo front rotor, and the rear of the 964 Turbo is a very different hat to the naturally aspirated 964.
Rick,
This is great information.
Is there support for the 964 Turbo? I think the hat would need to be different for the 964 Turbo vs 993 Turbo front rotor, and the rear of the 964 Turbo is a very different hat to the naturally aspirated 964.
The 964 turbo hat is 5mm taller than the 993TT/RS hat up front. If you have the stock 964 turbo/RS uprights you would need the taller hat.
It is interesting, my friend has been trying to source front calipers for the Dauer Homologation car and although we can't find any solid documentation, all the experts and cars we looked at RR7 use a variation of the old 993TT/94T big red caliper. Amazing the 917 had pads no larger than the 930 and 964 C4/C2's and the 962 no bigger than the later turbos. Boy have times and technology changed. Although a little difference in weight between them. LOL
FYI I posted the info about the 992 calipers in case someone has an interest but I think even with 600 RWH my car should be fine with the big red front/993 RS setup but will probably up it to a 350mm rotor once I wear out the first set.
12-29-2023, 08:36 AM
