Evil Bunny

This has been covered a several times, I have made extensive use of the search function and have lots of info, however prior to stepping onto the slippery slope I am hoping for some advice..,

1990 C2, so 4 pots up front and 2 pots at the rear, mechanically the brakes are fine, however cosmetically the lacquer is coming off, in addition they are 25 years old and ideally need a refurb, as oppose to going down the refurb road, the sensible road, I have opted for a set of 993 C2 calipers, which I believe to be the same as those fitted to the 964 RS. (Fronts are 44/36 but without the 10mm RS boss, Rears are 30/34.)

Rears
I believe that the rear calipers simply bolt on? I want crossed drilled discs, am I right in assuming that the only option is the OEM 964 RS/968 M030 (951.352.041.91)? – Is there anything else to consider?

Front
Calipers, I do not at this time wish to change the uprights, so I believe I will need a caliper adapter, can any provide an opinion on if I am better off going for an adapter that allows me to run a 304mm disc, or the larger 322mm 964 RS disc?
Provided of course my assumption on the two options I have mentioned are correct? – Where is best to purchase the adapters?

Are there any pros / cons of either disc option in relation to performance, availability, disc options, cost? – I should also mention that I would like cross drilled discs to match the RS items on the rear. - Can anyone provide the parts numbers / dimensions of the cross drilled disc options I have available to me based on my caliper choice?

Master Cylinder / Pipe Work / Brake Boost
At this moment in time I do not wish to change any of this, does this present any immediate issues ?

Have I missed anything? Are there other items/factors I should be considering?

I should also add that the upgrade is primarily an ascetic one, the car will not see track work, well, at least that is my current thinking!

Any help appreciated.

jellonailer

Pull the guts from your proportioning valve. I believe stock is 45 bar, turbo 55 bar.

Bill V is the man on this.

I did this. With PFC 08 pads my stopping power is unbelievable.

cobalt

the medium S4 calipers used on the 91-92 turbo/RS and 993N/A is normally paired with the larger heavier 322x32mm rotor. There are several suppliers of adapters rennline is one. They should work because the caliper sits the same distance out as the big red/black but has a 10mm shorter body and pad. the only option for rear cast hole rotors are the 968 M030 rears with the 993N/A calipers anything else will cost you the hand brake.

Picture of my 93 with M030 cast hole rotors and 993 rear brakes.

ilko

Tony, you know that box in the corner is federal property, right?

Evil Bunny

Thanks for the info regarding the rears, M030 it is.

In relation to the fronts, would I be right in assuming that the pad contact area using the medium S4 is the same on the 304mm disc as it is on the 322mm disc? - The advantage of the larger disc being heat dissipation?

In regards to the 322mm discs to ensure I get the right off-set would I be looking for the 964 3.3 Turbo discs?

cobalt

Yeah the mailman left here one day by mistake, I returned it after I replaced the tags back on my mattress.

Yep you assume correctly. There are several options for the fronts if you go with the bigger disks. Factory turbo 3.3 S4 322mm rotors which are pricey. 94 turbo 3.6 322mm rotors which give you additional meat at the bottom of the rotor you will not use. The 928GTS front rotors which are solid vs cast hole otherwise same as the 94 turbo rotor or you could do the 993TT front rotor again you would not use the bottom meat of the rotor but requires a different adapter to compensate for the 5mm shorter hat. the advantage to the 993 offset is that the hat can be unbolted and aftermarket coleman disks can be mounted at a small savings or you can go with slotted rotors with those hats or there are aluminum hats available for a small weight savings per corner.

Sounds like you are pretty much on your way and have the facts down.

FlyinTomato

does anyone speak French? This document has so much data on different models, years calipers and rotors. great reference, hope someone can translate it to english. Google translate isn't working so well sometimes.
http://www.924cup.fr/doc/Bible-freins-PMA.pdf

Bill Verburg

true

sortta, the964RS9643.3T front caliper body is 10mm shorter than the 993tt/993RS/9633.6t big red or 928GTS big black, and it does use the 322x32mm rotor, but the reason is that these calipers incorporate a 10mm mounting boss not found on the otherwise identical 993/928S4 caliper

there are 2 different caliper adapters which depend on whether 928/964 rotors or 993 rotors are used these differ in axial o/s. It is true that the radial o/s is used no matter which rotor is used. The choices are 304 or 322mm.

so assuming that 928/964 rotors are used w/ stock steel wheel carriers
use 304x32 from a 928S4(plain) w/ 993 front caliper
or use 322x32 a 928GTS(plain) or 964RS/0643.3t holey w/ big red/black or w/ 964RS/064 3.3t front calipers
both of the above use the same caliper adapter, Rennline or VCI would be good places to look for these.

for holey rears the only choice w/ stock parking brake is the 968M030 rears, if holey isn't necessary stock 964 rears may be used.

the stock 964C2 uses a 20.6mm master cylinder, this is marginal and gives way too much travel and way too little volume for a given stroke. The 993 93.8 or 964RS 25.4 will give you a much more comfortable and useable pedal. The 993 vacuum 23.8 is a bolt on swap, the RS is much more involved.

Evil Bunny

Chaps, thanks for the replies thus far, the rears are now complete so it is onto the fronts.

"so assuming that 928/964 rotors are used w/ stock steel wheel carriers
use 304x32 from a 928S4(plain) w/ 993 front caliper"

"or use 322x32 a 928GTS(plain) or 964RS/0643.3t holey w/ big red/black or w/ 964RS/064 3.3t front calipers"


Is there anyway in which I can use the stock wheel carrier/upright, the medium S4 caliper from a 993 C2 (No RS Boss) and run a 322mm x 32mm drilled disc?

If so which adapter do I need and which discs to ensure all offsets are correct? I am comfortable with the unused meat on the disc.

Thanks

Bill Verburg

You would have to use additional spacers to move the caliper out from the axle, thus emulating the built in boss arrangement on the 964RS/ 3.3t calipers

V

Hey Anthony

So if I buy 993 C2 rear brakes and 968 M030 rear discs, do I need adapters or anything like that to make it work on a 964? A 993 M/C would be good also? For the front 993 big reds with 993 uprights (normal aluminum, not 993RS ones).

ilko

No adapter necessary, I just did this on my car:

Mezger

Can hazz much sexiness!

DobermanDad

Out of curiosity, What's the difference between the 964 C4 rear calipers and the 993 rears? Other than how they look off course. Both are 4 pots correct?

cobalt

Piston size. Stock 964 uses 28/30 vs the turbo and 993 which use 30/34.