I have read two separate bits of info for our 928s that I am tryingto sort out.

First, it is widely said that a 332mm rotor ( or is it 330?) is the largest rotor you can install on a Porsche with the 993TT braking system (and GTS calipers are the same thing).

Even more, some distributors are noted as saying that the rotors mentioned above are the largest rotor you can fit in the caliper itself.

Then, in the same breath, you read that the 993TT calipers are sold with kits to OTHER cars that include 350mm rotors or even bigger.




Anyone have any info?

 

Okay....

 

By moving the caliper outwards with the bracket that you suggest, it would indeed incease the leverage that that same pad surface had on stopping that wheel and car. I was tryingt o figure out why we were limited to 332 (or in Devek's cataloug 322) and others were not for the same caliper. I think you have come to the conclusion on that though STerling.

Anybody else?

PS - Did you get your cams?

 

prospeed motorsports (not much of anything anymore) has a site up still, and he says that there are Alcon rotors available in 332, that would work with rotor hats. They alcon rotors are 440 each, and the 322 mm porsche ones are 175 each. INteresting if nothing else.

I wanted something with the rotor hats, like Devek's two piece, or maybe I will make my own. The other of the big two don't have the two piece systems for the later cars like yours and mine.

 

I think the larger diameter rotor could cause mechanical interferance between the caliper and rotor, which would require the rotor to be moved away and the pads to hang off the edge of the rotor. Brake pads are generally radiused to match the outer diameter of the rotor, so even if they fit in a normal position, the widest part of the pad would end up slightly inboard of the rotor's edge, reducing slightly the gain of the larger rotor.
However if the same calipers could be fitted to larger diameter rotors and pads that matched the new rotor's diameter fitted to the calipers, all would be good.
Sound reasonable?

 

The 322mmz32mm is the rotor that is used when someone upgrade thier 928 to GTS or 993TT calipers with a bigger, two piece rotor.

I know this to be fact.

What I do not know is if the calipers mentioned will deal with a larger diameter rotor. The rotors don't get THICKER, they just get bigger in diameter, to the point that 996 guys are putting 380mm rotors on. But I will not be changing the calipers, so my pad surface will be the same.

So thereby, the only real improvement may be in the added MASS of the bigger rotor (which will be paid for in ride/handling), and the added leverage that gripping a larger diameter rotor will have.

Any comments?

 

Will the caliper be moved out to grab the disc further from the center?

A bigger disc would dissipate heat better. More surface area.

 

I know what your question is about rotor diameter and the acceptance of your current caliper. BUT, why are you interested in this? Are you trying to maximize clamping force/ braking torque or thermal loading/heat loss? Couldn't you just upgrade the caliper and leave the rotor to gain the brake torque increase? If for cooling, could you upgrade the vein design or thickness with different temp pads? I'm sure you have thougt about this more than I, but was just curious what other avenues you have thought out. LOL

 

Well, I will probably be getting the 322mm rotor, as i have the big reds and hats required to make the 322 work.

I am trying to figure out if I can go bigger, though I will do this down the road