Jamie Summers

Bill and / or anyone else,
I have a query on my brake set up on my 964 C2.........

Currently I am running standard 993 calipers front and rear together with 964 rear rotors and 928 S4 front rotors (same as 944 Turbo ??). I also have the 964 Turbo 60 bar proportioning valve.

My query relates to the front caliper and rotor mix. From what I can tell from your extremely useful brake usage guides, the 993 front caliper is the same as used on the Euro 964 RS, yet the 964 RS used a larger diameter front rotor. I am just wondering why it is not possible to fit the larger 964 RS front rotor to the C2 ? I just can't find any comment on this anywhere..... My guess is that there is some difference between the caliper mounting points and hubs on the C2 and RS that means the RS is able to fit the larger diameter rotors ??? and presumably to update to the RS hub / mounting is either impossible or prohibitively expensive ???

Having said that, I hear of plenty of people who claim to have fitted RS calipers and Turbo rotors. Do they infact mean that they have installed 993 calipers and 944 Turbo rotors (ie what I have) rather than the larger 964 Turbo rotors ?

Apologies if this is a dumb question, answered many times before, but I just can't seem to find the answer anywhere ........

Thanks,

Jamie

Christer

Jamie, the 964RS does not use a 993 caliper on the front - it is in fact the 964 Turbo 2 (not 3.6) caliper and rotor. The 964RS rear is what (now) uses the 993 rear caliper (and I forget whether it is in fact the 993 rotor or whether it is still the 964RS rear rotor which is also the same as the 968 Clubsport or something). I have this set up and I needed mounting adapters to fit the front calipers, but other than that there is no issue with this modification. Where you have hit a wall is with the assumption that the front caliper on a 964RS is a 993 caliper...because it is not.

Hope that helps....?

Christer

p.s. - I have never heard of *anyone* that has fitted 993 brakes to their 964 before.....was it you that carried out this mod? If so, why did you decide to go that route?

Christer

p.p.s. - I left the standard pv valve in place - and have had no issues that I have noticed anyway......

AVoyvoda

"I have never heard of *anyone* that has fitted 993 brakes to their 964 before"

A fellow Rennlister in Germany did just that, some years ago. Fitted standard 993 front and rear brakes to a 964. He tells me they are lighter and more effective. No problems.

Christer

They are lighter even though they are bigger.....I am impressed I know for a fact that my 964RS front calipers/discs are far larger and I assume therefore they weigh more....

Jamie Summers

Christer,
Thanks for your response. Perhaps I have misunderstood Bill's chart, but it does seem to suggest that the RS uses the S4/993 front caliper. Clearly this doesn't seem to be the case !!!
Anyway I thought that the 993 caliper upgrade was a pretty standard one - I'm pretty sure there are plenty of people on Rennlist who have done this ?? It's a very easy one to do and a heck of a lot cheaper than the Big Red option. As I put in my first post you use the 993 front caliper with the same adapter bracket as the Big Red (and probably RS), and mate it with the 928S4/944T/968MO30 304/32 (I think) front rotor. Rear uses standard 993 caliper and standard 964 rotor (can use RS - it is the same size, just drilled).
I've been running this set up for a year now and have found it pretty effective, I was just merely wondering if it would be possible to use a slightly bigger rotor to get a bit more leverage on the front.
Do you happen to know what the difference is between the 993 front caliper and the RS / 964 Turbo ?

Thanks,

Jamie

Christer

Jamie, I have just looked at the chart you mnetion and it does say that the 964RS/993/)64Turbo all use an 'S4' caliper....so maybe I am totally mistaken.......but I am sure I have seen a 993 front caliper next to a Turbo/RS caliper and it seemed smaller to me...but the chart definitely says not....so I don't know what to think I am afraid!

AVoyvoda

"They are lighter even though they are bigger"

I think you'll find that the 993 front callipers are lighter, at 4.5 kgs vis 5.7 kgs for the 964. Which compensates for the increased weight of the larger 993 disks.

Red rooster

Jamie,
I have RS front calipers and 322 x 32 RS/964 turbo rotors. The RS and 993 front caliper are the same thing !
I am intrigued to know what adaptors are on your car to allow 302 rotors .
Reason for my interest is that they would allow the use of 16 inch wheels - better for snow tires !!!
The commonly available adaptors are for 322s .

TIA

Geoff

Jamie Summers

Hmmmm, the plot thickens. The adapters I am using are the 9m ones.
http://www.porschetuning.co.uk/html/...4&parentid=350
There really doesn't seem to be enough space to get a larger diameter rotor inside the caliper with my set up and I'm pretty sure the S4 rotor is only 304mm. The advice I had from Bill at the time of doing the upgrade was that when using the 993 front caliper you need to use the 928S4 rotor, and now I'm just not sure why.
Very intrigued and a little confused !!!!

Jamie

Christer

Well, all I am saying is that I picked up the 964RS caliper I have installed (which now seems to be the same as the 993 caliper) in one hand and the much smaller 964 front caliper in the other hand when I swapped them over and my memory doesn't match your data...but in aaaaaany case I am happy that I therefore apparently have a lighter caliper than before....

Red rooster

Jamie,
I think you will have to measure your front rotors !! Those brackets are for 322 rotors . The 928S4 has 322 x32 non crossdrilled rotors with a pad area for big red / S4 pads ( only a caliper color change ! ) .
I had a look at adaptor design for 304 rotors and found it looked pretty tight .

I guess you are running 17 inch wheels ??

All the best

Geoff

garrett376

The 964RS caliper is different from the 993 caliper - but only in that the "PORSCHE" script written on the side is a different font and bigger, and there are ribs on the caliper siding versus having a smooth appearance as on the 993. The size is the same as you guys pointed out (S4).

garrett376

The crossover pipe is on the wrong side with 928 calipers due to the different mounting orientation on the front brakes... but that's easily removed and installed in the correct position.