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.
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.
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
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
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.
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
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->)