Zulu Alpha

Why Movit instead of PFCs?

GrantG

Larger and Lighter carbon rotors gives the advantages of PCCB (handling, braking, acceleration, ride comfort improvements from lower rotating/unsprung mass) while lasting WAY longer (not just a thin veneer of carbon-ceramic friction surface , full thickness that barely wears and can even be repaired). PFC's are steel in the smaller stock dimensions (but you don't get the advantage of 18" wheels with the GT3 that you do with the Cup).

Update: Upon receiving additional information from an end-user of the Movits - it seems that they too can be overheated to the point that their longtime use can be jeopardized (despite showing no visible wear). So, maybe we are still at the point that steels are preferable for hard track use.

But if using steels, I am not sure exactly what benefits one would gain from the PFC system on a street-driven GT3 (aside from a cosmetic appearance some may prefer). Pure race calipers often have no piston dust seals and can be problematic if one doesn't intend to service them often.

Zulu Alpha

Thanks for clarifying that Grant, much appreciated.

True CCBs (Movit, or others/PCCBs) will have a slight advantage in terms of breaking, handling, longer ware etc. But for track duty it's better to go with steels as the cost to benefit with CCBs don't justify, unless I am a top budget race team (which I'm clearly not).

The reason I mention PFCs, is because it would be nice to have better performance of PFC Cup (if any, as a pose to OEM Brembo) for the cost of steels.

If going for Movit, why not go with standard PCCBs? I'm not familiar with Movit, that's why I ask.

Elephant Bart

It's not clear if Porsche decided to go with PFC brakes because of performance advantage or because of clearance issues. in another thread (link) I demonstrated how the front calipers will not clear 18" wheels on the cup car. The change to PFC from Brembo may be as simple as that. Brembo brakes may be just as adequate on the track as PFC.

Spyerx

My shop has already done a few side deletes with mid pipes and center on 991 gt3. Sounds sweet.

Mike in CA

Grant, according to Porsche, the Gen III PCCB's developed for the 918 and used on the GT3, have a much higher ceramic content than the previous versions. Do you (or anyone) have any hard information on how much of a difference there is and how the new PCCB's might compare to aftermarket offerings? If we're still dealing with a ceramic veneer is it at least a thicker veneer?

Elephant Bart

If it helps at all, here's a picture of PCCB rotor from a 2014 C2S. I think this is the same setup that's optional on the GT3. Correct me if I'm wrong.

Jake951

Another great article from Elephant Bart! Thanks for posting this.

Mike in CA

Thanks, Bart. Someone correct ME if I'm wrong, but I'm pretty sure that the new 410mm front and 390mm rear ceramics from the 918 are only available on the Turbo and the GT3. I don't think they are yet available across the model range which would include the 2014 C2S. The Carrera brakes are about $1K cheaper. The size of the new brakes is also printed on the rotor hub....

GrantG

I think you are right. Aside from larger dimensions, I am not sure how the compostion of the rotors may differ between PCCB on 991S and GT3.

Zulu Alpha

Thanks for clarifying, and yes I read which I very much thoughrouhly enjoyed! Thank you very much.

It would be interesting to know the performance comparison between the Brembo and PFC on track and whether it's worth a swap. But as your last sentence says, Brembo might be just as adequate as PFC on track.

paradocs98

Thanks for your hard work--very informative! A few thoughts and questions:

• The choice of 20" wheels on the street car intrigues me. The cynic in me says that Porsche chose 20" wheels as more of a nod toward fashion trends, and not performance. This disappoints me. I think this because the Boxster and Cayman S come with 20" wheels, which are clearly too large for such a small car. The brakes get lost in those giant wagon wheels, but they sure have 'bling.' Porsche probably felt that, if the Boxster and Cayman had 20" wheels, the GT3 certainly had to have them as well, especially if they're pitching this new car to more of a mainstream audience.
• So, then, did Porsche first decide on 20" wheels as a design parameter, and then just designed suspension components with the knowledge that they had plenty of clearance available? Or did the suspension design and rear steering mechanism, etc., come first, which necessitated a 20" wheel?
• Similarly, the brakes. It's telling that drilled rotors are used on the street car, while the Cup car has slotted rotors. Slotted rotors have been proven time and time again to be superior on track in race applications, but they have less of a 'bling' factor than drilled rotors. So once again Porsche makes a design/equipment decision on the street car for a nod to mass appeal, rather than for pure performance.
• Are the changes made to the suspension of the Cup car purely based on the need to fit an 18" wheel, as mandated by many of the race series, or are the changes primarily based on improving the street suspension to make it more fitting for track use?

Once again, thanks for all the info!

reidry

Is the 991 GT3 steel drilled rotor lighter than cup slotted rotor?

Drilling is cheaper than slotting.

Ryan