Porsche gearbox background:

The very first Porsche gearbox was a transaxle (a common case sharing the gear stack and the differential). All Porsche 356-997 street and race cars share this same design theory. From the first 356 design through the 1980s 911s, Porsche used their own design synchronizers. Even with several evolutions of their own designs, they still proved to be problematic.

The Porsche 911 transmission took on a huge improvement in reliability, durability, and ease of operation in 1987 with Porsche design 950, commonly called the G50 gearbox. They are used from 1987 to present day in all 911, 964, 993, 996, and 997-bodied cars. These gearboxes, made by Getrag, use the Borg-Warner (Ford) style synchromesh. A variant of this is still used in the 996/997 GT3, GT3R, and 996/997TT/GT2 cars.

As with the earlier Porsche transmissions, Porsche has manufactured many different gear ratios, as well as ring and pinion sets to allow the gearboxes to be set up for virtually any kind of driving. Most of the street car gearing is selected with fuel economy in mind, so there are many opportunities for performance improvements with changing gear sets or ring and pinions. The first version of the gearbox was a 5-speed, but with introduction of the 993 brought on a 6-speed version of the G50 gearbox. The 993TT and four-wheel drive 993 and 993 4S use a similar gearbox with a driveshaft that extends through the nosecone to drive the front wheels.

The G96 gearbox was introduced at the start of production 996/986 cars. The most noticeable difference in these gearboxes is the cable shifter. All 996/986 cars other than 1998-early 1999 996 GT3 cars use a cable shifter.

The 996 GT3 gearbox is different (type G96.90, G96.93, G96.96) from the standard 996. The GT3 gearbox has evolved from the 993 GT2 which, in turn, evolved from the 993 TT, and before that, the 1989 930 G50.50. The 996 GT3 box is also used in the 996TT/GT2 and 996 GT3 Cup/GT3 RS/RSR race cars. It has a dedicated oil pump and external oil/water intercooler, steel synchronizer rings on gears 3-5, and interchangeable gear ratios (main shaft assembled from individual ratios that are positioned, not pressed into place), and a 40% / 60% asymmetrical clutch type limited slip differential.

At the end of the 996 GT3RSR production, the sequential gear selection capability came to Porsche racing, the G97 6-speed gearbox was born. Holinger Engineering was consulted for design and production of the internal gear sets. The 997 Cup brought the sequential to mainstream production. The 997 GT3 RSR also uses the same type dog engagement design. Externally, these gearboxes look the same as their predecessor G96 boxes, using many of the same castings, coolers, oil pump, etc. These transmissions have proven themselves to be quite reliable, and as before offering quite a wide range of gear selections. Early 996 Cup/GT3Rs can be converted to sequential capabilities if a customer so desires.

After a year or so of testing, the 2008 997 GT3RSR introduced a new "clean sheet of paper" design to the transaxle. With Porsche's recent supercar the V-10 engined Carrera GT, a new manufacturer (Hör) was brought in to design the 6-speed gearbox. This manufacturer also designed and developed Porsche's new gearbox for the RS Spyder. This successful relationship with Porsche Motorsport also brought new eyes to one of the biggest issues with the G50 based gearbox. In the Porsche race world the axle geometry has been an issue for the past two decades. As the cars are lowered for racing, the axles tend to have more and more extreme angles, causing axle failure. This issue has been resolved with the new design. The gearbox is also lighter, and focused on details internally to decrease the friction on contact points.

More info can also be found at : www.gt3r.com

Porsche gearbox designations:

519 = 356 based 4 speed first Porsche designed box introduced in 1952
716 = 356 based 4 speed (58-59)
741 = 356 based 4 speed (59-65)
901 = 911 based 4 and 5 speeds (65-71), a derivative also used in all 914 (70-76)
915 = 911 based 4 and 5 speeds (72-86)
925 = Sportomatic (semi-automatic transmission)
930 = 911 turbo/915 based 4 speed (75-88)
G50 = 911/930 based 5 speed (87-89)
G64 = 964 based 5 speed (89-94)
G93 = 993 based 6 speed (95-99)
G86 = 986/Boxster gearbox (97-04)
G96 = 996 gearboxes (98-05)
G87 = 987/Boxster gearbox (05->)
G97 = 997 gearboxes (05->)