Upgraded the front rotors from OEM cross drilled to Girodisc slotted.

The Girodisc are 8% larger (340mm vs 317mm) and fit using the stock caliper with a reduction in weight from 9.0kg to 7.8kg per disc. The increased diameter provides a larger effective radius giving more braking force for the same system pressure. I really didn't want to go down the Brembo BBK route requiring almost a complete new disc/caliper system and pressure/bias changes.

Here you can see the quality...





And here the size comparison with the OEM...






It's a very easy install, the only difference to the usual disc change is the addition of the 12mm spacer to move the caliper further away from the arm. The spacers are included in the kit together with 12mm longer caliper bolts (strangely Porsche part numbered?).





Finished...



Thanks to Craig at rennstore for all the info and help...

Now I just have to see how they compare on track...

 

niceee whats the Price Diffrence between OEM and This? Will it fit under a 18" Turbo Twist II with the Larger Disc?

 

Nice pics, thanks for posting!

 

It looks like a good alternative to the Brembo's! Thanks for sharing.

 

Price is aprox $1100 give or take the odd 'deal' going on. Obviously allot more than stock but cheaper than a full Brembo set up or 'Turbo' upgrade. Plus they will last longer, reduce the dreaded rust issue and perform better.

They will fit under standard 18" rims according to manufacturer.

 

Is it better than the turbo breakes though? Because the C4S has Turbo breakes from the factory...

 

Is this just for the front?

 

This is just the fronts and it doesn't 'upset' the bias. The 'Turbo/C4S' brakes are smaller and also allot heavier (330mm 10.9kg vs 340mm 7.8kg). If I wanted to replace calipers, rotors and then adjust the system I'd probably go with the GT3 6 pots and Alcons...

 

so you loose 2.4kg in rotating mass which is great, and the larger size allows for better heat dissipation but with the same callipers and pads as the stock size there isn't any improvement in stopping distance, just and improvement in brake fade correct?

what do 2 front stock disks cost? seems like $1100 is pretty steep!

 

There are three main benefits to these larger discs:

1) Increased surface area = increasing cooling = less fade

2) Decrease in unsprung weight. The Girodisc front discs offer a 18% improvement in surface area-to-weight for the rotor.

3) Increased braking: Torque = Force x Distance, brake torque is equal to the retarding force provided by friction between the pads and discs, multiplied by the radius of the contact point between the pad and disc. The increased diameter provides a larger effective radius, or torque arm the pads act upon, giving more braking force for the same system pressure...

 

I don't think number 3 is true as the lever arm distance of the calipers to the centerline of the axle has not changed.

 

Yes it has, by 12mm, hence the spacer...

 

sorry - you are correct I didn't look at the photo closely enough.

 

Not challenging your statements but just trying to understand #1. I believe cooling is affected by metal volume and surface area. So if you increase either, the result is greater heat dissipation. So in the current GiroDisc application, if metal volume has been reduced and surface area increased, has GiroDisc confirmed through tests that greater heat dissipation is the result? I guess the hats, which might not contribute to original heat loss, might be lighter .... hmmm, I might have answered my own question.

 

From the manufacturer website:

"More heat sink without a weight penalty: The Girodisc disc set weights in a little lighter than the OE system but with an important advantage. The rotors have grown in diameter. This means that weight has been transferred from the center hat were it does nothing to the outer diameter where it is actively absorbing and dispersing heat. More heat sink without a weight penalty."