Jamie Summers

Bill,
Thanks, I think we're there now !!! So in terms of my original suposition, I wasn't right about there being a difference in the hub mounting on the 964 RS vs the C2, the difference is that the RS caliper has 9mm taller mounting lugs vs the 993 caliper which allows the use of the 322/32 rotor rather than the smaller 304 rotor (despite the two calipers otherwise being largely the same).

This clearly begs the question as to whether one can use 9mm spacers in conjunction with the standard adapter bracket and the 993 caliper to allow the use of the 322 rotor, or is this a very bad idea ???? My guess would be that having 9mm bigger adapters machined would be prohibitively expensive .................

Thanks,

Jamie

Bill Gregory

I wouldn't want to do that, as that creates another set of surfaces that can slide against each other, which would be undesireable in the braking system.

If you want 322mm rotors, use the right calipers. If you want holey rotors in 304mm, they are available (remember, cast holes not drilled).

Jamie Summers

Thanks Bill, thought as much ! I might try to get some bigger adapters made up by my girlfriend's grandfather, who's a retired engineer. I can't remember having seen a set of 964T / 964RS calipers for sale in the Uk - more likely to find a set of Big Reds !

As for the holey rotors, despite all advice to the contrary I have decided to try a set of Zimmerman drilled. I think this is worth a go as my car is pretty light on brakes as it stands - I have two days on the Spa GP circuit next week, so we'll see how they go ............. From what I can find there really aren't any UK suppliers of 'cast hole' rotors other than Porsche OE and the 968MO30 rotors are more than twice the price of the Zimmermans, and I can't believe that they are more than twice as good. Given that on a track car you are likely to replace the discs through cracking before wear becomes an issue I just can't believe I will get less than half of the life out of then Zimmermans. It may be a false economy, but I need to prove it to myself before I fork out US$325 per rotor for the OE versions !!!

Jamie

Red rooster

Bill,
Thanks for your explanations. It all makes sense now !! I honestley thought the 964RS calipers and 993 were the same !! I knew the 9mm number but hadnt made the caliper connection !!! Douuuuuugh .
A couple of friends with 993s have fitted 9mm caliper spacers and , I thought , 964 RS rotors .
I am puzzled as to how that works if the offset on 993 rotors is different to 964 . Or is the difference minimal ??

All the best

Geoff

Bill Gregory

As I recall, 993 rotor offset is about 5mm different than 964 rotors.

Red rooster

Bill ,
Thanks .

Geoff