Porsche 911 991 vs 992 GT3: battle of the gearbox

Both these Weissach superstars are equipped with the same six-speed manual gearbox from Porsche Motorsport… but can Total 911 find any tangible differences between the two?

Written by Lee Sible

BATTLE OF THE GEARBOX

MANUAL GT3S DO BATTLE

Motorsport’s brilliant 991.2 takes on 992

North Wales. A glorious pocket of the UK, where the locals are friendly, the scenery is pretty and the roads are twisty. Never mind God’s country, today it’s GT3 country, our two stunning examples from the 991 and 992 generation playing cat and mouse on the slithers of blacktop running through vibrant, green topography.

Ahead of me, Phil Farrell is carving a fast line through the cambered curves in his Carmine red 991.2 GT3, the howl from its exhaust reverberating around the Welsh hills. I’m in hot pursuit in a Gentian blue, Touring specification 992 GT3, its low, wide nose hunting the tall uprights and shark-fin end plates mounted to the 991.2’s sculptural wing. We’ve covered these two glittering Porsche 911s in broader detail before, but today we’re back on winding asphalt to delve a little deeper into just one aspect that makes them both so special: their gearboxes.

The history of Porsche’s six-speed ‘box in the company’s GT product is well known. Binned for the 991.1 GT3 generation in 2013 when Andreas Preuninger famously announced PDK would be the de-facto transmission for Porsche GT cars going forward, a public outcry led to this decision being reversed. It was the 911 R in 2016 that first revived a manual stick-shift in a Weissach car, the U-turn complete when Porsche introduced the 991.2 GT3 a year later, when enthusiasts could choose either PDK or manual. By 2018, Porsche was producing a Touring version of said GT3, where any choice of transmission was once again removed, this time with stick shift being the compulsory gearbox.

For the current 992 generation, both manual and PDK are once again on the table, this time for both winged and Touring variants. Thus, equilibrium has returned to the Porsche GT stable, certainly in the eyes of purists who believe a manual transmission is to be at the epicentre of a car delivering such a visceral, driver-focused experience.

And so to today, and the B4391 in Snowdonia. We’ve sung the praises of this road in Total 911 many times before, the 8.2 miles from Ffestiniog towards Bala being a road we know very well. It’s the perfect stage to get these two exquisite GT3s dancing, and means I can focus more on the intricacies of their gearboxes rather than whether the next corner is likely to be a long left or hard right.

Both these GT3s use a six-speed manual gearbox to put 500-odd horses through the rear wheels (via a mechanical LSD), developed by the ‘wizards of Weissach’ at Porsche Motorsport. In fact, these two manual transmissions in the 991 and 992 GT3 share rather a lot… because on paper they’re exactly the same.

That’s right: the same number of gears, identical ratios and even mass – although while we can’t ascertain the exact weight of Porsche Motorsport’s six-speed manual gearbox (unless anybody has a GT3, a set of scales and a spare afternoon?), we do know a 991 GT3 is 17kg lighter if it has a manual gearbox fitted rather than a PDK. This 17kg difference is also evident in manual-to-PDK 992s, even though the 992 platform overall is 5kg heavier than the 991.

So if both gearboxes are the same, what on earth are we doing on a chilly spring morning in Wales, trying to split hairs?

Well, dear reader, you should know by now that with Porsche, identical numbers on paper don’t always correlate to the same physical feeling from where it matters – the driver’s seat. Just ask anyone who’s driven a 381bhp 996.2 GT3, and a 381bhp 996 GT3 RS. Porsche has proven time and again over the years that these cars really are more than the sum of their parts, and so splitting hairs is all part of the fun on this magazine.

With the GT3s still warm from our early-morning game of cat-and-mouse, I slide into the driver’s seat of the 991. Turning the engine over, it settles to a bassy, burbling idle, offset by a metallic chattering of the single mass flywheel. And right there, we’ve already stumbled across a key difference between the two cars: the 991 being winged means it comes with an optional single-mass flywheel (this isn’t available on Touring-spec cars in the 991 and 992 generation, to help differentiate between them and that halo 911 R). Pulling on to the road and again chasing Phil, who this time is piloting the 992 Touring, it takes all of a couple of hundred yards – and two cog swaps – to realise there’s very much a difference between the shift in the 991 and 992 GT3.

For a start, it feels as though there’s less travel to the shift in the 991 over the 992. The short, stubby form of both shifters is identical, and so the sensation isn’t synthetic, either. In the 991 there’s simply less movement required to move the shifter into each gear. It’s not quite as rifle-bolt as the legendary 911 R, but it does give a tighter, more direct feel over the 992. It’s marginal, don’t get me wrong, but very much apparent.

There’s more weight to the 991 GT3’s shifter itself too, with a definitive snick through each gate, reminiscent of the excellent, feel some throw in a 997.2 GT3 RS. It all adds up to a more mechanical feel in the 991.2 GT3 when compared to the 992, the shifter of which feels superficially light at times. Again, the margins are slight, but clearly identifiable. The 992’s shift by contrast is more fluid, and you can really throw its lever around with ease. It’s ideal for tighter sections of these twisting roads where cog swaps are more frequent.

What’s most interesting here is that, if anything, you’d expect this difference to be the other way around. After all, the 991 GT3 with nearly 10,000 miles on the clock has been ‘worn in’, whereas the 992 has only just surpassed its 932-mile breaking in period. Nevertheless, it can be argued these idiosyncrasies play rather nicely into the specific functions of these two GT3s. The winged car, being more track focused, requires an altogether more aggressive driving style for fast lap times, and so a little more weight behind the shifter may aid a more positive throw. The Touring, in contrast, is designed to deliver high engagement on winding mountain roads, where a fluid shift could be more welcome.

The clutch pedal on the 991 is lighter than that of the 992 – which you’d expect, because the 991 is rocking the single-mass flywheel compared to the 992’s dual-mass item. However, the difference, certainly in terms of feel, isn’t as great as you’d expect. Both cars and their gearboxes come equipped with an arsenal of tech to help the driver get the most from them. An example of this is a rev-matching feature. Purists may baulk at its very concept, let alone presence, yet it actually works very well. Engaged automatically in Sport mode, the feature ensures smooth gear changes, most pleasingly so in the upper echelons of that mammoth nine grand rev range. If you don’t wish to use the rev-matching feature, just stay in Normal mode, or venture into the PCM to turn it off in Sport.

Another cool feature of both GT3s is the ability to flat shift, meaning you can keep on the gas while depressing the clutch pedal and reaching for a higher gear, only this time without destroying your clutch. This is because engine speed is automatically controlled by the car’s ECU during this process, allowing for quicker gear changes, even if it’s only by a few precious milliseconds. This feature may conjure some ‘nanny state GT3’ jibes, but in a car that revs so freely and so fast, my view is that any tech which can help us mere mortals keep up with it is most welcome. The reality is if you don’t wish to use the flat shift feature then, well… don’t!

On these roads, we spend our time switching mainly between second and third gears, only dropping to first for a super-tight right-hander, eeking out the revs each time to a cacophony of noise before changeups. On these roads, the cars are downright playful, and it’s a joy to drive them. A PDK equivalent would offer up a different kind of fun, but right now both Phil and I are pleased to be part of the 40 per cent of modern GT3 drivers who opted for a third pedal. So, on paper, yes, the transmissions in these cars are the same. However, right where it matters – in the driver’s seat – there are clear differences between the manual 991 and 992 GT3. I myself prefer the weightiness of the shifter in the 991, yet find favour with the fluidity of the shift in the 992.

Of course, there’s no right or wrong answer here. As ever with Porsche, it’s a case of choosing the right setup for you. Both GT3s are mesmerising machines and exquisite examples of automotive art, representing the high watermark of what just might, in years to come, be viewed as the golden era of the sports car, their manual gearbox at the heart of what makes them so special.

“I myself prefer the weightiness of the shifter in the 991, yet find favour with the fluidity of the shift in the 992”

BELOW The 992’s shifter is lighter in the hand than the 991’s, which suits multiple gear changes along a twisting section of road.

BELOW While the shifters in both cars are just as short as each other, it requires less movement in the 991 to change gears.

991 VS 992 GT3 MANUAL GEARBOX RATIOS

• CAR 992 GT3
• DRIVE SYSTEM: Rear-wheel drive
• GEARBOX: Six-speed, GT Sport transmission; Porsche Torque Vectoring (PTV) including mechanically rear differential lock with asymmetric locking rate (30 per cent traction, 37 per cent overrun) Gear ratios
• FIRST GEAR: 3.75
• SECOND GEAR: 2.38
• THIRD GEAR: 1.72
• FOURTH GEAR: 1.34
• FIFTH GEAR: 1.08
• SIXTH GEAR: 0.88
• REVERSE GEAR: 3.42
• REAR AXLE RATIO: 3.96

• CAR 991 GT3
• DRIVE SYSTEM: Rear-wheel drive
• GEARBOX: Six-speed, GT Sport transmission; Porsche Torque Vectoring (PTV) including mechanically rear differential lock with asymmetric locking rate (30 per cent traction, 37 per cent overrun) Gear ratios
• FIRST GEAR: 3.75
• SECOND GEAR: 2.38
• THIRD GEAR: 1.72
• FOURTH GEAR: 1.34
• FIFTH GEAR: 1.08
• SIXTH GEAR: 0.88
• REVERSE GEAR: 3.42
• REAR AXLE RATIO: 3.96