The VIR shakedown really brought to light the long legs of the GT3 transmission. With a 3.44 ring and pinion and 0.85 6th gear, I never even made it into 6th gear on the back straight. The back straight at VIR isn’t exactly short, it measures 4000 ft, that’s a good three quarters of a mile!
The diagnosis was clear: The gearbox would have to be rebuilt with shorter gears. I reached out to my friend and Porsche expert, Hans Lapine, who put me in touch with his 996 Cup guru, Lance Aspesi at Dutchstone Global Services. I told Lance that I thought the ratios of the G96/91 (996 GT3 Cup) transmission looked pretty good to me. Lance thought that changing the ring and pinion from 3.44 to 4.0 would give us the desired result. The G96 transmission of the GT3 is different from the one in the non-GT 996 cars. Its roots can be traced back to the iconic G50 transmission, no wonder that Porsche was still using it in 2004!
After Lance pulled the transmission he discovered that it was on its last leg. One of the previous owners had tracked the car without properly servicing the transmission oil (the rule of thumb is to change it after every track event). The ring and pinion needed to be replaced (which we were doing anyway), all the bearings were shot and there was damage to the main housing due to the excessive bearing wear and movement of the output shaft. Lance built up the surface and machined back to spec.
The Guard limited slip differential looked good but the shop who did the initial installation had used threadlocker and didn’t follow the correct torque procedures. In order to remove all the bolts, some of them had to be cut off without causing damage to the end plate. There was also a cracked thrust washer inside the differential but luckily it hadn’t caused any damage.
The stock dual-mass flywheel was still present but it had seen better days. As they don’t have a very long service life, Lance suggested a single-mass lightweight flywheel. Then a case of “while you’re here, you might as well” set in and I ended up with Cup shifter cables, metal shifter bushings, a new 4th gear, new single-mass lightweight flywheel, new pilot bearing, new clutch, new pressure plate, new throw-out bearing, new guide tubes and new bearings for every gear. In other words, I got a brand new transmission.
Porsche factory parts don’t grow on trees and with the rebuild bill growing by the day I was thrilled that Harry Season had reached out to me in regards to an original painting he coveted. As the president of the Roadrunner Region of the Porsche Club of America, he was quite fond of the original 930 painting that I had been commissioned to paint. This painting served as the poster and T-shirt art of the 50th anniversary of the clubs existence. Harry and I quickly struck a deal: He would receive the original painting and I could cover the bill of my G96 transmission. Win-Win.
The new rebuilt transmission really transformed the car. It’s quicker off the line and the lightweight single-mass flywheel lets the engine spin up immediately. The fuel consumption suffers a bit, but that’s no surprise. And of course, the best part is the sound: At idle with the car in neutral and the clutch engaged it sounds like you have a bag of marbles in your gearbox: Just like a 996 Cup!