Using a vacuüm operated diaphragm clutch and a 4 speed trans-axle the Sportomatic was a Porsche rave in 1976. As the driver, you would get to run your 911 without ever having to shift. Still, if you looked inside, you would clearly see that there a stick shift between a driver and passenger.
The Porsche Sportomatic is surprisingly similar to the early 4 speed manual transmission, with also having on the reverse a sliding gear to make a parking lock arrangement.
Using the vacuum servo arrangement, gear changing occurs automatically by having the clutch move in an opposite direction than your traditional manual clutch shifting. To drive using the Sportomatic is actually very nice, and very easy. All you is jump in, then stick in the key. Upon starting, the familiar Porsche engine sounds completely 911. The stick shift is completely 911 as well, in which all you do is shift into gear, and off you go.
Porsche’s biggest reason for even providing this option was for a growing youth of US drivers that just did not know or want to fool with a clutch. Even now, less and less car manufacturers are providing clutches and the problem will become an issue as manual transmission sales continue to dwindle to the hardest core shifter only car drivers, like myself. What was more remarkable was Porsche designers were completely was aware exactly how none sportsmanlike having a traditional automatic transmission was in the sports car world. Reinventing a special breed of sports cars, what Porsche did was then to make a “Sportomatic transmission”, a kind of semi automatic shifter that the Porsche driver would need to control. This kind of transmission wasn’t causing the driver to need to manipulate foot to clutch to shifting timing. This also got rid of some very notorious bad habits, like the infamous over-rev. You bet. Since this kind of transmission is not full automatic, it requires the driver to think of shifting gears like in a regular 4 speed. Start rolling in first gear… maybe get up to rolling speed in second and then third and fourth but the sound of the engine. There was never a fifth gear in those days.
Here at A. Bauer Porsche, we see them occasionally. Most of them had ended up getting damaged, and then it turns out they changed out to the five speed manual transmission. To change them out you will have to do some modifications to get them installed. Others, should one be lucky to get parts, can get them repaired with factory specifications.
The Sportomatic transmission option, (cost adding almost was not factory isolated option for the 911, but was also provided on five experimental pre 1972 914/6 as well. Amazing!!!
If you happen to have a Sportomatic Porsche, make sure to keep it because its rare, and more importantly don’t convert it to manual transmission.