Slippydiff said:The rear disc diameter on a 3.4 Mk 1 or a 3.6 Mk2 996 is the same, 299mm.
The front discs are 318mm diameter on both models also.
As I understand it, the front calipers will fit onto the rear of the car. The mounting bolt spacing (130mm) is the same, but the piston sizes are different to the OE rear caliper pistons and can create excessive rear bias.
I'm currently in the R&D stages of producing various options for 2 piece floating front and rear discs for the non-GT 996 C2 and C4 models.
Here are some images of the larger 340mm front discs I'm currently testing :
along with the larger 325mm rear discs. These were only fitted to the car yesterday afternoon, hence the surface grinding marks are still present:
With the standard 996 C2/C4 rear calipers, you'll struggle to get anything bigger than the 325mm rear discs inside them.
I'm currently also developing a larger front disc which will be intended for track use, but will just fit inside the standard 4 piston 996 C2/C4front caliper.
Using 350mm front discs and 6 pots is overkill really. I'd be surprised if your brake bias isn't somewhat sub-optimal now.
Those one piece OE 350mm Cayenne discs are heavy too (as are the calipers and pads)
Normally it's stated that "mass is your friend" when it comes to brake discs, but that has to be balanced against the negatives of excessive unsprung weight on suspension and steering.
The 340mm front 2 piece discs I'm utilising are a kilo lighter than the OE one piece 318mm discs (and that's taking into account the 800g for the alloy bell)
The larger, thicker front 2 piece discs I propose making available for tack use, will weigh the same as the stock OE 318mm one piece front disc (again taking into account the weight of the alloy bell) but will be considerably larger diameter, slightly thicker, and better ventilated, so the pads should last longer, and provide more consistent performance along with more stable disc/pad temperatures.
The images I've posted of the 340mm front and 325mm rear 2 piece discs feature cross bolted floating disc to bell mountings, they're THE best quality AP Racing fastener sets which utilise forged bolts, not off the shelf grade 8.8/10.9 or 12.9 capheads.
There will be an option to upgrade to a fully floating bobbin style arrangement for the 340mm front discs (but this option is really overkill for road use) but the larger/thicker front discs which will be intended for track use, will only be available with the fully floating bobbin mounting arrangement.
I've yet to finalise costs, as material costs are still increasing monthly.
I'll be starting a new thread on the 996 forum about the discs in the next few days, firstly to gauge what demand may be, as is usual in these matters, the higher the demand, the lower the component costs will be, but also to field any questions potential purchasers of the product may have.
As a footnote I should add ALL the components used in the discs/bells are British manufactured.
This kit looks very well thought out, would be interested to see how this works out compared to a full stock overhaul.
The one things that sticks with me though is the lack of bite/feel of 996 C2 brakes. I also have an E46 M3 and that stock was passable but not anything to write home about. I Soon fixed that with Alcons howver want to keep the 996 stockish maybe improving the pedal feel?
