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YOUR RESEARCH'Doubling-the clutch' on downshift: Good practice or Showing Off?
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Run errands, 1st gear and 2nd gear are all i
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Hell, I can do 60 mph in second, and for around town running errands, 1st gear and 2nd gear are all I use.
'Doubling-the clutch' on downshift: Good practice or Showing Off?
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Leading evidence: 'Run errands, 1st gear and 2nd gear are all i' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'result of previous owners efforts' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Run errands, 1st gear and 2nd gear are all i' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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' (turn the 'M' upside down for clarity - its an oft used Aussie colloquialism that may be equally applied to a good mate, or the doode who just cut you off in traffic).
'Doubling-the clutch' on downshift: Good practice or Showing Off?
result of previous owners efforts
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Suspected cause
the shifting experience with each of my 911s go progressively downhill, likely the result of previous owners efforts to be heroes in the newer and newer cars.
'Doubling-the clutch' on downshift: Good practice or Showing Off?
Use broad powerband of the engine
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Suggestion
I actually try to not use the clutch very much but I do use the broad powerband of the engine.
'Doubling-the clutch' on downshift: Good practice or Showing Off?
Use clutch most of the time
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Suggestion
That truck, you didn't even have to use the clutch most of the time.
'Doubling-the clutch' on downshift: Good practice or Showing Off?
Use aussie colloquialism
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' (turn the 'M' upside down for clarity - its an oft used Aussie colloquialism that may be equally applied to a good mate, or the doode who just cut you off in traffic).
'Doubling-the clutch' on downshift: Good practice or Showing Off?
Use heal-toe if needed
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Suggestion
Yes, wear can be taken off the synchros by matching rpms as best possible, but the engine coming down during a normal shift when shifting up, and using a heal-toe if needed when shifting down, is more than sufficient.
'Doubling-the clutch' on downshift: Good practice or Showing Off?
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result of previous owners efforts
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Suspected cause
the shifting experience with each of my 911s go progressively downhill, likely the result of previous owners efforts to be heroes in the newer and newer cars.
'Doubling-the clutch' on downshift: Good practice or Showing Off?
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I grew up in Australia driving a Landrover Series IIA (who am I kidding, I drive a Porsche... so I skipped the 'growing up' step
). Anywho the 'crash' gearbox on that beastie required doubling the clutch on the downshift (disengage the clutch in neutral and press the accelerator to match the predicted transmission speed in the lower gear, before re-engaging the clutch and dropping into that gear). The double clutching is particularly finicky on a 3-2 downshift in most transmissions because the 3rd gear is typically a lot taller, plus this is often executed as you corner at an intersection with a few other things going on in the cockpit and on the road.
All my life, I have 'doubled the clutch' on downshift by default on all my stick-shift cars. This is partially out of habit, but also because I understand that: a) it eases the mechanical strain on the synchro (and thus the wear - promoting longer transmission life), and b) it moderately improves performance in the downshifted gear.
Fast forward too many decades and 15 years of ho-hum, disengaged auto transmission driving in LA traffic, and I'm now living the boyhood dream with a backup ride in a 22 y.o. Porsche 996 C4 Cab (recently acquired). Doubling the clutch on the downshift just feels right, but with the powerful engine in this puppy and the growling exhaust - I fear it is signaling '
Manker at the wheel
' (turn the 'M' upside down for clarity - its an oft used Aussie colloquialism that may be equally applied to a good mate, or the doode who just cut you off in traffic).
So, members of the Rennlist jury: Is doubling the clutch on downshift in a 996 defensible on mechanical and/or performance grounds; or should I stop besmearing the good name of fellow 996 drivers with my childish, show-pony antics? Technical inputs requested... unfortunately the "...
it sounds cool
..." arguments won't assuage the jaundiced eye of my wife (though it does demotivate her presence in the shot-gun seat, permitting me more unsupervised playtime).
I just bring the revs up in neutral with the clutch in during the downshift. Double clutching seems frivolous in a modern synchromesh car, but it certainly can't hurt and if you enjoy it then why stop?
Double clutching is doubling the wear on all the clutch components. I actually try to not use the clutch very much but I do use the broad powerband of the engine. Hell, I can do 60 mph in second, and for around town running errands, 1st gear and 2nd gear are all I use. The transmission is synchomesh so double clutching and RPM matching is a waste. You're just wearing stuff out. IMHO
OK... the middle ground: 'performance'... prep the engine revs at higher RPM without drive train load before re-engaging the transmission. Makes sense, but you argue for a no mechanical/wear advantage on the synchro gears?
I'd be pretty surprised if well executed double-clutching effectively makes any noticeable change to clutch life as compared to a standard heel-toe downshift, but I have no actual evidence to support this.
Downshifting without rev-matching at all seems like a bad idea though... Even in a modern car.
I thought I was alone with double clutching. That was how my dad taught me as a bonus after I learned to drive a manual. He said that was how truckers did it but never gave it much thought until recently as I have started to teach one of my kids to drive a manual. I picked up a technique from an article I read and it helped my son,learn without all the herky jerk motions when I learned. After he started to get it I told him, now I am going to teach you to double clutch and he gave me a WTF look�lol
oh and that fast and furious gearbox is missing additional reverse gears..lol
So yes on the double clutch for the toterhome, 10spd trans and no syncros, rpm match or double clutch is the only way.
On ther car its a big no. 1st and 2nd gear in that trans r both double syncroed. U r just wasting your leg and not doing the car and favors. Honestly it will just make u slower.
U need to know your equipment and treat it appropriately.
Agreed. Double clutching is an artifact of old transmissions that didn't have a synchromesh. Most large commercial truck gearboxes don't have synchromesh, however a 911 is not an 18-wheeler, and shouldn't need to be shifted like one.
Yes, wear can be taken off the synchros by matching rpms as best possible, but the engine coming down during a normal shift when shifting up, and using a heal-toe if needed when shifting down, is more than sufficient.
My 2-cents, IMHO, etc.
I actually DO double-clutch shift 1st-2nd and especially 3rd-2nd when the tranny is cold. Just like keeping the revs below 4K until oil is hot. If you look up weaknesses in Porsche transmissions, it’s my understanding it’s their synchros. Also, slows down shifts.
Thanks to all members of the jury for your insights. I now have a new T-shirt on order with an anchor on it, and my clutch-doubling days are in the rear view — though a little rev matching with the clutch in may be retained on the shift as I "...
learn my equipment
...". I am new to living this long-held Porsche dream and wondering why I waited so long - what a blast! I've lived at my current home for 7 years and never realized Mount Wilson was on the way to nearest milk, toilet paper, post office, ATM, etc, etc...
As for my wife in the shotgun seat... if she asks why I don't double the clutch any more, the answer will of course be because I know she doesn't like it!
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Pressure on the shifter, light lift and your out of gear, in with the clutch put it in gear release clutch.. Its main benefit is it slows you down just enough to let all the synchro's do their job and you don't hit the new gear under full throttle.
A power shifted Getrag is a broken Getrag.. Even the monster ones..
I have an O L D truck that has no syncro gears. I know I should double clutch that thing, but I just don�t know how, so I simply hold the clutch in until RPM is basically idle, then find the next gear slowly. I never learned how, and I don�t drive that truck fast enough to care.
The 911, on the other hand - heel and toe downshifts on the most mundane corners. Just for the fun of it.
On the 996 it�s really not necessary but I do a double-clutch heel-and-toe downshift just for the fun of it. The 915 transmission in my �72, really likes to be double-clutched though, it shifts effortlessly that way.
Rev-matching without double-clutching saves the clutch, but you still wear out the synchros. And I don�t buy that double-clutching wears the clutch faster, that sounds like nonsense to me.
I double clutch all the times in all my manual gearboxes but that is out of habit. As for showing off, I am almost never driving with anyone else so I am just showing off to myself.
During a summer job at a local dairy, I had the opportunity to daily drive a Mack twin-stick, which required a two-step, one hand on the wheel sometimes two hands on the levers, and double-clutching was the only way for me almost every time. So after owning a variety of Volkswagon beetles over many years, a series of 356's, and now with a 996 cab, it's heel and toe all the way. It somehow feels right...although I do miss the sound of those forgiving four-cylinder air-cooled motors and how simple they were to repair.
Similar experience. I drove a Detroit diesel straight truck and had to match gears or double clutch. That truck, you didn't even have to use the clutch most of the time.
Agreed. The 915 in my 72 is butter. You can sneak it into the next gear with the back side of your small finger. the shifting experience with each of my 911s go progressively downhill, likely the result of previous owners efforts to be heroes in the newer and newer cars. I'm blaming it on video games. As a result my 996 requires the most attention to get it shifted properly. Granted, a first world problem and the result of higher mileage, by my choice of cars. Actually, I find it kind of satisfying and challenging in a way. It sure makes a difference during the first 20 minutes of cold transmission fluid I can tell you.
