G50 vs 915 gearbox – What are the differences?

Anyone interested in a Porsche 911 Carrera 3.2 will inevitably have heard or read the terms 915 and G50 gearbox. There are endless discussions about advantages, price differences and so on. But why does the question of the transmission dominate discussions about the popular G-model? What are the differences between the 915 and G50 gearboxes? Which is the better choice?

Porsche 915 – Stuttgart’s 70s gearbox

The 915 transmission was developed in-house by Porsche and was first used in 1972. Essentially, the Porsche 915 gearbox is a revision of the Porsche 901 gearbox that was used in the 911 F-model. Due to the constantly increasing torque of the engines, a new gearbox was needed that could cope with this. It was installed from model year (MY) 1972 to 1986 and was used in the 911 Carrera 3.0 and 3.2 as well as the 911 Carrera RS 2.7, among others. Until MY 1977, it was available with four or five gears, from MY 1978 exclusively with five gears. Reverse gear is always at the bottom right. The clutch is cable-operated.

From today’s perspective, the 915 gearbox has a few design peculiarities. Firstly, it has no springs that automatically return the gear knob to the center shift gate. This means that clean gear changes are essential. Another special feature of the Porsche 915 transmission is its synchromesh. It serves to smoothly adjust the different speeds of the individual gear wheels and the transmission shaft. This means that it is no longer absolutely necessary to use the clutch when shifting up or blipping the throttle when shifting down in order to achieve smooth gear changes.

Porsche used a solution developed and patented by Ferdinand Porsche. In contrast to the synchronizers commonly used today, the Porsche system does not prevent from shifting before the speeds of shaft and gear wheels were equalized. In principle, this enables fast gear changes with low shifting forces, but it wears out more quickly than the locking synchromesh designed by Borg-Warner commonly used today.

From MY 1987, the G50 gearbox produced by Getrag replaced the 915

After more than ten years, Porsche decided to retire the 915 gearbox. Ever-increasing engine power and growing torque required a new step in transmission development. As a replacement, the Stuttgart-based company chose the G50 gearbox manufactured by Getrag for the 1987 model year.

It differed significantly from the 915 in terms of synchromesh and general design. Instead of relying on the Porsche synchromesh as before, the G50 used a synchronization system developed by Borg-Warner. This synchromesh is generally known to be more durable and less susceptible to wear than the Porsche’s system in the 915.

Spring locks were also used for better and more precise shifting. As a result, the gearshift jumps independently into the gate for third and fourth gear, as is common today. Reverse is now at the top left. The clutch was operated hydraulically on the G50. This meant that less force was required. In the 911 Carrera 3.2 and 964 it had five gears, in the later 993 it was available with six gears until MY 1997.

What stands out in a direct comparison between the Porsche 915 and the Getrag G50?

The deeper we delve into the matter, the more exciting the direct comparison of the two gearboxes becomes. Because while the G50 is the technical winner at first glance, the driving pleasure is not so clear-cut. The driving performance of the Porsche 911 Carrera 3.2 before and from model year 1987 onwards makes you wonder. The earlier Porsche 911 Carrera 3.2 with 915 gearbox accelerated from standstill to 100 km/h in 6.1 seconds, just like the later G50 models. There is also no difference in top speed, with both versions achieving 245 kph/152 mph.

In addition, the Porsche 911 Carrera 3.2 with 915 transmission even feels a little livelier subjectively. This is due to the lower weight of the transmission itself as well as the clutch and flywheel. As a result, engines with 915 gearboxes rev up faster. In general, the G50 itself is reinforced and heavier in many parts. In combination with the heavier clutch and flywheel, the G50 drivetrain weighs twelve kilograms more. As a result, a 3.2 liter boxer engine with G50 transmission does not rev up and down quite as spontaneously as with the previous transmission.

It is also interesting to take a look at the gear ratios. While they are slightly shorter with the G50 transmission, a longer final drive ratio equalizes the effect. As a result, the rev level in the first four gears is slightly lower in Carrera 3.2s with G50 gearboxes than in with 915-equipped cars.

What are the advantages of the G50 gearbox over the Porsche 915?

So it’s not the driving performance that tips the scales in favor of the G50 transmission. Reliability, on the other hand, speaks in favor of the G50. This is because the gears and synchronization are simply designed to be stronger and more durable. In many cases, a well-treated G50 transmission will outlive the engine.

It also reacts less sensitively to wear in the shift linkage than its predecessor. If the bushings are worn, the gearshift feels imprecise very quickly. The result: increased play in the gear lever, mechanically imprecise gear changes and increased wear on the gearbox. In the worst case, gears can no longer be engaged without grinding or two gears are engaged at the same time. The gearbox must then be disassembled in any case.

That’s why a 915 gearbox that doesn’t shift properly is always a bit of a gamble when buying a 911. Either it is just the linkage or, in the worst case, the synchromesh. If the gearbox has to be dismantled, more worn parts are usually revealed than originally thought. This is why the price of a gearbox overhaul can only be determined afterwards.

The costs of an overhaul tend to be higher for the G50 gearbox

Due to its stronger design, G50 gearboxes tended to be overhauled less frequently. However, there is a small but: if something does break on the G50, the costs are usually higher than for the 915. Although the differences are no longer as big as they were five to ten years ago, there is still a price gap.

Porsche 911 Carrera 3.2 with 915 gearbox offered on Elferspot

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In terms of price, late Porsche 911 Carrera 3.2s are generally still slightly more expensive than earlier models. This is not only due to the change from 915 to G50 for the 1987 model year, but of course it has its share. G50 Carreras cost around 5,000 euros more than their 915 siblings. Is it causality or correlation that the price difference is not far off the price of a gearbox revision?

A Porsche 915 gearbox is not worse than a G50, but different!

Of course, a Porsche 911 Carrera 3.2 with G50 transmission feels more modern. The hydraulic clutch requires less force and shifting gears is easier for newcomers to classic Porsches. However, a professionally adjusted and well-maintained 915 transmission conveys a charm that the G50 cannot. It takes its driver on a journey back to the 70s!

All Porsche 911 Carrera 3.2 with G50 gearbox listed for sale on Elferspot

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The 915 driving experience is truly special and quintessentially 70s Porsche. It takes a little time to get used to. It also requires more driving skill. But that is precisely why there is something sublime about mastering the peculiarities of the 915 and it rewards you with great driving pleasure. The greater the challenge, the greater the victory – as the ancient Romans already knew. And that is exactly the case here.

The comparison between the 915 and G50 would probably not be such a big issue if both had not been used in the same model. Because let’s be honest: Does anyone mind the 915 gearbox in the Porsche 911 Carrera 3.0 or even RS 2.7?

Of course, the suitability factor for everyday use no longer plays a major role in most classic Porsche sports cars today. However, the G50 transmission offers easier access, especially for occasional drivers. The shifting feel is much closer to that of a modern gearbox than the 915. Our recommendation is therefore: if you like to get actively involved with driving techniques and want to experience the retro charm of the 70s, you can opt for a Carrera with a 915 without any regrets. Those who prefer the best of both worlds are best served by a late G50 Carrera.