Fabio421

Is is possible to fit a 350mm rotor up front? If so, it may be possible to use the 6 piston giant front calipers from the cayenne. These are only $500 a pair and are HUGE. WHat say you P-car wizards?

If your answer is no, what about with spacers on a widebody?

hacker-pschorr

I doubt they will just bolt up to the stock spindal, so the amount of fabrication required to make it fit, then anything is possible at that point.

Alan

Is there a functional reason why you'd want bigger than GTS brakes? I can honestly say I have never felt these brakes needed any upgrading - they are simply amazing.

Are you thinking it will be cheaper than GTS brakes? - I've never priced them out so I wouldn't know...

But is it really $500 for a pair each of rotors and calipers? sounds too cheap...

Alan

Jim Morton

Fabio:

Yes, it is possible, but there are other fitments issues to resolve.

Usually, with the 350/355mm rotors, you need to run a true 18" wheel to clear the caliper. Given the 928 front spindle, I also suspect that the caliper shape and how it protrudes forward is another wheel fitment challenge.

FWIW, I am in the process of upgrading the brakes on my GTS. I will be using Alcon rotors upfront using aluminum mounting hats being clamped with Ferrari F50 calipers. In the rear, I am using the 965 (3.6T) rotors with 993RS calipers. As soon as the rear rotors arrive, this setup will be installed.

As a suggestion, make sure you are confident with why you want to alter the rotor diameter / caliper specs. Be sure to know the hydraulic changes that come with the caliper you are considering and how both the change in mechanical torque and hydraulic clamping affects the bias. If you make these changes without considering the affects, you can box yourself into a bias scenario that is VERY unpleasant to drive !

$0.02

Jim bailey - 928 International

But, but , but Jim ; bigger is ALWAYS BETTER ....no matter what she may tell you Seriously you make excellent points about the brake bias, fluid requirements etc. which is often overlooked.

Tom in Austin

Sure, one key would be an adapter to mount the new Caliper into the same relative position to the rotor as on the donor Cayenne. The size, shape and other characteristics of the adapter would have to be engineered to be compatible with the 928 spindle. Say you had GTS brakes to begin with, which are 320 mm in diameter, you'd probably need a smaller and less critical adapter than if you were running an earlier model using smaller brakes. Second, the offset in the rotor hat would have to be considered for correct alignment to the caliper.

Besides the caliper and rotor offset, you'd want to verify clearances for wheel diameter, backing plates, tie rod ends, brake hoses, etc.

I'm sure I've seen aftermarket brake upgrade kits larger than GTS, so someone like Brembo may already offer this solution under their brand name. It is very likely the Cayenne design is offered elsewhere as an upgrade; I don't think Porsche limits what other channels Brembo can use to sell their products.

Fabio421

The reason I ask is because you always see people looking to upgrade their brakes on the 928's. The big reds are pretty expensive. If you could have brakes that are larger for less $$$ then it may be a good option. Even if it is only applicable to racers.

drnick

i would rather think about finding an aftermarket supplier of cerramic discs and try and fit those. reducing the weight would be worthwhile which you might achieve with the bigger rotors as you would be using aluminium mounting hats.

Jim Morton

Questions are always good...

The challenge when modding brakes is to end up with a system that is both balanced and achieves the improvement.

It may sound funny, but if I were not afraid of heights with this affecting me during decents on twisty mountain road passes, I would find the GTS brakes quite adequate. As I want to rally drive my GTS as I did my 993TT, I would like brakes similar in capacity to those I had on my TT.... :^)

Enjoy the mods !

BC

The adaptor issue is "technically" better, it seems, when you have the early spindes, as then you can have the normal "Axial/Radial" adaptor made to the proper specs. 951 guys have put GT3R calipers on and it seems to work.

I was thinking of this, as the newer monoblock calipers, even though they are BIGGER, are LIGHTER than our BBs.

The S4 spindle presents a challenge as it looks like it would be a Radial/Radial adaptor.

Jim, how did you accomplish this if you feel like sharing?

Jim Morton

Brendan:

As I am working with the spindle ***'y of the GTS, I have the radial setup. I am using the Brmebo F50 caliper which has the same bolt spacing so I simply use a spacer (like the Brembo GT kit does) to set the caliper at the correct radial distance.

The rotor hat is the issue. The are many places to have rotor hats made to order. Most raod racing supplies offer this service.

IMHO, a key item is to check the caliper piston diameters and pad swept areas when choosing a caliper. Do consider the working parameter of the brakes over the potential wieght savings of one caliper vs. another. If you fight the brakes while driving, the benefits of the unsprung weight savings will be lost...

$0.02

BC

Thanks Jim. I did not know the F50 calipers has the same spacing.

A larger master could be required.

I am working on some hats, and once I do that I can make any spacing if I wanted to do this in the future.

You'll have to show us all your setup when done.

IcemanG17

I think Mark Anderson runs F50 brakes on his race car....

Jim
What about keeping the GTS calipers...changing pads & getting a two piece "hat" design rotor......I heard that the F50 and GTS brakes use the same brake pads.....so the swept area should be the same...just with a larger rotor to aid cooling?

slate blue

I have F50 brakes up front and for my car it was just a bolt on part. The thing is that my car uses an adaptor, well of kinds anyway, I wont bore you with those details they aren't important but that is a way around the hat issue as there is plenty of 993 hats around. You need 18" wheels or this will not work.

Greg

Jim Morton

Brian:

The GTS or "Big Red" caliper is quite heavy compared to the F50. Also, the pads are quite different in both shape and mounting.

Unfortunately, it will not be long before either the "Big Red" or F50 calipers will be NLA. Depsite visual similarities, the newer "monoblock" Brembo calipers are not a straight swap as the F50 or Big Red units are.... too bad.

Also, do not overlook the design and material of the rotor as a large factor to braking performance. The pad / rotor combo plays a much larger role in braking performance than most folks figure.

It's ALL fun !