If there’s one question that comes up here at Paul Stephens, more than any other, it’s that of the Type 915 gearbox versus the G50 gearbox, as fitted to the 911 Carrera 3.2.
Air-cooled 911s are, of course, a PS speciality and within that remit, the Carrera 3.2 (and the 911 SC) is probably the air-cooled 911 that we sell and deal with the most. Not surprising, given that Porsche built over 70,000 of them and it was by far the best-selling air-cooled 911 in the UK.
So, when it comes to the relative merits of the two transmissions, we have both experience and an opinion. Market forces and perceived wisdom point to the later – 1987 on – G50 gearbox cars as being the most desirable, with a better shift action over the earlier 915 equipped cars. In simplistic terms, that maybe true, but there’s rather more to it than that. So here’s the PS take on the 915 v G50.
Type 915 gearbox
Developed from the original 911 Type 901 gearbox, the 915 was introduced in 1972 to handle the increased torque demands of the 2.4-litre engines. Available in both and four and five-speeds, it featured a more conventional shift pattern. That is to say first being forward, and second back, rather than the 901’s dog-leg, back for first, forward for second etc.
Like the previous 901 ‘box, the 915 uses Porsche’s own synchromesh design. Good or bad – depending on your point of view – this is what gives the 915 gearbox its own distinct feel, which we will come to. The 915 ‘box also has a cable operated clutch. This too, has a bearing on the ‘feel’ of the ‘box in operation.
The 915 was Porsche’s go to 911 transmission from 1972 to 1986, and remained largely unchanged save for an external oil cooler, developed to help cope with the extra torque demands of the 231bhp Carrera 3.2 engine.
Getrag G50 gearbox
All hail the G50… Introduced in 1987, the G50 was as much a nod to the future of 911 development, as it was a replacement to the 915. As such it was designed to handle more power and torque and saw action in the Carrera 3.2 through to the 993 and was tough enough for the Turbo models too.
Crucially the G50 ‘box uses a Borg-Warner designed synchro and a hydraulically operated clutch. There’s no doubting that both these advances give the G50 gearbox a quicker and smoother shift over the Type 915 gearbox. However…
Weight and ratios
This is where it starts to get more interesting. There are many that maintain that a 915 equipped 3.2 Carrera ‘feels’
quicker and more agile than a G50 car, and there’s good reason for that.
The G50 gearbox is heavier than the 915 by 12kg (including clutch and flywheel). That’s weight that you can feel at the rear of the car. There are other factors that make the 915 equipped car lighter too. Bottom line a 915 Carrera 3.2 weighs 1160kg v 1210kg for G50 Carrera 3.2.
Then, there’s matter of gear ratios, or more importantly the final drive ratio. The G50 does have shorter 1st to 5th ratios , than the 915, but that’s to overcome an eco and emissions mandated (sound familiar?) taller final drive ratio of 9.31 (3.444) v 8.31 (3.875). The bottom line is that the shorter ratios in the G50, never really get on top of that taller final drive ratio.
Type 915/G50 gear ratios
- 1st gear: 3.182 – 3.500
- 2nd gear: 1.883 – 2.059
- 3rd gear: 1.261 – 1.409
- 4th gear: 0.965 – 1.074
- 5th gear: 0.763 – 0.861
- Final drive ratio: 3.875 – 3.444
Result? It may be marginal, but it’s not your imagination: A 915 equipped Carrera 3.2, does feel livelier and more responsive to drive. The proof is in the figures.
Type 915 equipped 911 Carrera 3.2
- Top speed: 152mph
- 0-60mph: 6.1secs
G50 equipped 911 Carrera 3.2
- Top speed: 149mph
- 0-60mph: 6.3 secs
The driving experience
This is really what it’s all about.
First up, no one moans about the 915 ‘box in a Carrera 2.7 RS, do they, and that’s not because every other facet of an RS outshines the gearbox, as to make grumbling about it irrelevant. The 915 ‘box is an intrinsic part of the classic 911 driving experience.
The secret/technique and ‘feel’ to the driving the 915 ‘box is not to rush it. Unlike the G50, the 915 isn’t sprung from second to third, or coming down from fifth to fourth. You need to guide the lever and the shift, and it can feel a bit vague, but very quickly it will become second nature. Likewise, there is a ‘spring’ to the feel of the cable clutch.
Don’t rush it. Changing up through the gears, you will feel a slight drag of resistance before the synchro lets go, and the next gear slots into place. Don’t worry, there’s enough torque to cope with any drop in revs.
This applies even more when coming down the box. Don’t expect to rush up to a corner and rapidly lose two or three gears. Plan ahead, be methodical, it’s the 911 way. Heel and toeing is good but not essential. Just as with changing up, apply a bit of pressure on the lever to prime the synchro and then shift.
A truly obstructive 915 gearbox is at best: one that needs a good linkage overhaul, or at worst: one that’s been abused and rushed and therefore will need a rebuild to really put it right.
And the G50? Yep, it’s a slick-shifter all right and none of the above 915 characteristics really apply. Is it better? It’s certainly more modern and the clutch is lighter/smoother as all hydraulic clutches tend to be. Back in the 80s when your Carrera 3.2 might have seen daily action and even a spot of city driving, the G50 would be welcome over the 915, but now? Well call us perverse, but a 915 equipped 3.2 is classic 911, involving, agile and satisfying drive. It’s a more tangible connection with the 911’s past, rather than its 964 and 993 future.
Market forces
It goes without saying that the 87-89 G50 equipped Carrera 3.2s command a premium over 915 models. Even if the G50 ‘box had never appeared on the scene, a later car is a later car and therefore will be more sought after, with a higher value. That’s how it works. And for our part we will continue to look out for and offer for sale the best G50 cars around. After all, why wouldn’t we?
But don’t feel short-changed if an earlier 915 Carrera 3.2 is what your budget will stretch to. Indeed, the market is better for having the option of choice and for all of the above reasons, the 915 cars make a very strong case for themselves.
And of course there is a point in the 915 v G50 Carrera 3.2 market, where prices will converge. Just how important is the gearbox compared to overall condition or that colour that you really want? In a sea of Guard’s Red Carrera 3.2s, that could be a crucial factor. Decisions, decisions…
And finally
And finally, it’s not all about the gearbox is it? OK, we’re fighting the 915 corner here, perhaps playing a bit of Devil’s advocate, but more than anything it’s about the classic, air-cooled 911 experience isn’t it?
And in that, the gearbox is just a collection of cogs. Important, for sure, but not the be all and end all.
