As requested, here are some pictures.
A big thank you to both
@rossm and Krishna for trialing the discs and being part of the development, making sure we have no issues with brake balance and fitment. In the words of Ross:
Hi all, I am an early adopter of the SM front brake upgrade kit as my disks needed replacing and have now managed to do a couple of thousand miles since fitting. I own a 2015 Granturismo Sport (Auto) and mostly use the car for road trips and fast road driving. I also enjoy track days but have always used more suitable (lighter) cars for track fun – Vauxhall VX220, Westfield / Caterham, BMW M3s etc
I have always felt that the standard brake setup on the Granturismo was the car’s weakest aspect. The pedal feel has never been particularly firm or confidence inspiring despite bleeding the system through a few times with good quality fluid, and I have experienced a lengthening pedal on several occasions during spirited driving through the Alps / Wales etc. I also found that the brake feel was not consistent, sometimes being fairly sharp on initial application (normally in traffic!) and other times getting the heart thumping by needing a firmer shove than expected (when a bit warmer and pressing on). My car seems to exhibit a tendency to push on when transitioning from acceleration to hard braking as you do when pressing on on good roads, as if the engine and torque convertor are not fully backing off causing additional load on the already struggling brakes, I don’t know if that is a shared feeling from other owners of Auto cars?
Obviously the Granturismo is a heavy car focused more on GT capabilities and not pretending to be a super responsive sports car, but the lack of consistency with pedal feel and retardation was to me a big concern and I attributed this mainly to the OEM pad compound and also the lack of ability of the disks to manage heat well due to their relatively small size. I also found the aesthetics of 360mm disks under a 20” wheel was a little underwhelming and not up to the good looks of the rest of the Granturismo package.
The upgraded brake kit I opted for consists of larger 380mm floating disks with aluminium bells (reducing unsprung weight despite the larger disk diameter) and C hook grooves. You also get a pair of nicely milled brackets / spacers to offset the calipers for disk clearance, and all the mounting hardware required. I opted to try out some Stoptech street performance pads from Balance Motorsport (£163 delivered) to move away from the OEM Brembo pads that should handle a larger heat range without losing cold bite.
First impressions – the upgraded kit looks great and fills the wheel void out much more than the standard setup. The pads give good bite from cold, no squealing to date, and are fairly linear in brake response without dropping off in performance even when hot. And despite some concerted efforts to induce fade (including repeatedly accelerating and then standing on the brakes on a quiet dual carriageway) I haven’t experienced any loss of performance or sense of braking imbalance with the oversized front setup.
But the biggest improvement is in feel and consistency, this new package provides good feedback through the pedal and a much more trustworthy response. The car still feels heavy when braking hard, but with the upgraded kit the brakes are now a known quantity meaning you can actually learn and adapt to the expected braking distances and with that work with the car to drive more smoothly and confidently. This is definitely a worthwhile upgrade and interestingly was a no cost update to my insurance (Admiral).