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Unlike a "normal" manual transmission, where each pair of gears (1-2, 3-4, 5-6) are located together, the 7MT gears are scattered at random locations through the transmission:
This greatly complicates the problem of allowing the use of a normal H-pattern shifter, since unlike a traditional transmission where, for example shifting from 1 to 2 uses a single motion to disengage 1 and engage 2, each shift needs to disengage a gear in one place and then engage another gear in a different place. The transmission does this by having a separate shift rod for each gear. A carefully machined rotating shaft moves the two shafts as required for each shift gate (moving up and down between gates):
The following blog post (in Japanese) provides the details:
PDK has been very cleverly disguised as a manual in MT7 format. Wonder how history will view MT7 against 997 manuals. I suspect it will be another 993 vs 964 vs G series ....
that's because the 7 speed MT is a PDK box in disguise
AHHHH.....Got it!! The clutch pedal is just a pause switch, with a grind noise symposer and a neutral default if the shift sequence is not followed properly.
"the GTS uses a slightly modified version of the seven-speed manual, which now has a lighter, more positive shift that will soon be rolled out onto all 911s".
Unlike a "normal" manual transmission, where each pair of gears (1-2, 3-4, 5-6) are located together, the 7MT gears are scattered at random locations through the transmission:
This greatly complicates the problem of allowing the use of a normal H-pattern shifter, since unlike a traditional transmission where, for example shifting from 1 to 2 uses a single motion to disengage 1 and engage 2, each shift needs to disengage a gear in one place and then engage another gear in a different place. The transmission does this by having a separate shift rod for each gear. A carefully machined rotating shaft moves the two shafts as required for each shift gate (moving up and down between gates):
The following blog post (in Japanese) provides the details:
Trying to plow through the incomprehensible Google Translate English version you linked to is a truly Sisyphean task. To which I cried, "uncle!" So I can understand if you got the totally wrong impression about the 7MT gears being "scattered at random locations through the transmission." But the cutaways tell a different story, don't they?
In truth there is nothing random about it at all. 7th, 5th and 3rd gears in the PDK are in the exact same locations in the manual. It looks like 1st is in the same place too, though the cutaways are oriented differently so 1st is barely seen and not labeled at all on the PDK. But it sure looks to be in the same place. Likewise 2nd, 4th and 6th, all the same.
What maybe- MAYBE- they were trying to say but got Lost In Translation (great Bill Murray/Scarlett Johansson movie btw) is that the gears aren't laid out as they would be if the manual transmission had been designed as a, you know, manual transmission.
But its not, because it wasn't.
What we have here, quite clearly, is a PDK transmission, together with another transmission based on PDK but altered to tolerate human interference. Check out the color-coded parts. Only the three in green are unique to the manual- and it may only be two. I'm not so sure about 7th- all gears are the same except 3rd. The manual clearly copies the PDK, at least to the extent its able to given its inherent old school design limitations.
If you want to read a real true story about "Secrets of the 7MT" here it comes. The secret is: its not even a manual transmission. Its a PDK transmission compromised and downgraded to work with an old fashioned single clutch.
What maybe- MAYBE- they were trying to say but got Lost In Translation (great Bill Murray/Scarlett Johansson movie btw) is that the gears aren't laid out as they would be if the manual transmission had been designed as a, you know, manual transmission.
Yes, exactly.
The key differences between the PDK and 7MT are that the PDK has two input shafts, one for gears 1,3,5,7 and the other for 2,4,6 (and I think R), with the twin clutches engaging one shaft and disengaging the other to accomplish a shift, and the PDK has a different case to accommodate the electrohydraulics to manage the clutches and shifting.
The 7MT has all the gears on a single input shaft, but they're in the PDK order, which isn't random, but is clearly "wrong" for a manual transmission. The clever linkage system maps the traditional H-pattern into the PDK gear order.
Clearly PDK is the wave of the future, and the 7MT a sop to old people like me who can't abide an automatic transmission, but it's nice of Porsche to go to the trouble. And without getting into the whole PDK vs 7MT question, I would note that the 7MT is as nice or nicer than any "traditional" Porsche manual transmission that I've ever driven. And an extra $4000 in my pocket doesn't hurt either.
(BTW the 3rd and 7th gear ratios are different between PDK and 7MT, with a taller 3rd and a shorter 7th in the 7MT, leading to some complaints about the big rev drop from 2nd to 3rd with the 7MT.)
the 7MT a sop to old people like me who can't abide an automatic transmission, but it's nice of Porsche to go to the trouble. And without getting into the whole PDK vs 7MT question, I would note that the 7MT is as nice or nicer than any "traditional" Porsche manual transmission that I've ever driven. And an extra $4000 in my pocket doesn't hurt either.
(BTW the 3rd and 7th gear ratios are different between PDK and 7MT, with a taller 3rd and a shorter 7th in the 7MT, leading to some complaints about the big rev drop from 2nd to 3rd with the 7MT.)
Why would you say "old people like you"? I'm in my early 30's and refuse to buy an automatic as it takes away the fun of driving the sports car. I'd imagine I'm on the young end of Porsche 911 buyers
Why would you say "old people like you"? I'm in my early 30's and refuse to buy an automatic as it takes away the fun of driving the sports car. I'd imagine I'm on the young end of Porsche 911 buyers
I would have assumed that for most younger (under 30, or even 40) drivers, a manual transmission is an anachronistic affectation. In an old (pre-microprocessor) car, every control was directly connected to some greasy bit of the car, and part of the joy of driving was to get the car to do what you wanted through these imperfect, nonlinear, levers and pedals.
Nowadays, every interaction you have with the car is mediated through a computer of some kind. The desire to use a manual transmission recalls that earlier day, but it's fundamentally futile, because every other interaction is indirect. In a car like the 991, the computers do a much better job than the driver that by any quantitative measure they are superior (as reflected in the PDK's quicker acceleration time and, I think, better fuel economy).
I would have assumed that for most younger (under 30, or even 40) drivers, a manual transmission is an anachronistic affectation. In an old (pre-microprocessor) car, every control was directly connected to some greasy bit of the car, and part of the joy of driving was to get the car to do what you wanted through these imperfect, nonlinear, levers and pedals.
Nowadays, every interaction you have with the car is mediated through a computer of some kind. The desire to use a manual transmission recalls that earlier day, but it's fundamentally futile, because every other interaction is indirect. In a car like the 991, the computers do a much better job than the driver that by any quantitative measure they are superior (as reflected in the PDK's quicker acceleration time and, I think, better fuel economy).
I am in my early 30s and I also ordered a manual 911 as I don't get the enjoyment I get from driving a manual with an automatic. I actually asked a group of friends about the manual vs automatic and out of 5 of us only one preferred a automatic. All of us were 32-35 years old.
Clearly PDK is the wave of the future, and the 7MT a sop to old people like me who can't abide an automatic transmission, but it's nice of Porsche to go to the trouble. And without getting into the whole PDK vs 7MT question, I would note that the 7MT is as nice or nicer than any "traditional" Porsche manual transmission that I've ever driven. And an extra $4000 in my pocket doesn't hurt either.
Good one. Imagine how good they could have made the 7MT if it'd been a priority instead of a sop. Then it would have been a really, really good anachronistic affectation!
11-14-2014, 07:22 AM
Interesting article about 7MT
