shifting and double clutch instruction

[jmc1313]

You are doing the same thing I am doing. When you shift into neutral the gears are disconnected, let the engine revs drop to the correct rpm, shift into the next gear. Sam with downshifts, shift into neutral, increase the rpm’s to the right speed, shift into lower gear, no clutch required. You need to hit your rpm’s accurately but when you do it’s the smoothest ride possible.

[Solamar]

Forced to learn the above as a cheep teenager with a VW bug and broken clutch cable.

Came in handy later in life learning to drive tractor trailers. Clutch is only to get started, then it's just rev match shifting, and yes, same principle as double clutching.

[icarp]

Originally Posted by jmc1313

You are doing the same thing I am doing. When you shift into neutral the gears are disconnected, let the engine revs drop to the correct rpm, shift into the next gear. Sam with downshifts, shift into neutral, increase the rpm’s to the right speed, shift into lower gear, no clutch required. You need to hit your rpm’s accurately but when you do it’s the smoothest ride possible.

JMC, I'm not sure I agree with your explanation . The use of the clutch and the double clutch offers the smoothest shifting possible . The shifting of a racing dog box ,
Hewland , or the like is still best for the trans longevity to use the clutch on the down shift . Clutchlees upshifts are the fastest , but this is a racing transmission , torn down and rebuilt on a regular basis . So remember downshifting is not an emergency , just be smooth and efficient .

Shifting street gearbox without a clutch is possible , but not without wear on the inner parts .
So if you loose the clutch operation , you can still drive the car back to safety .

The purpose video is for the basic explanation of the double clutch operation, yes there are some modifications to the style and the execution . But for now lets stay with the basics .
Thanks for all the interest
Ian

[jmc1313]

People seem to think I’m advocating just slamming the transmission into gear. It’s more of a zen experience, rpm’s rising and falling in response to the input from the driver and road. When the speed is matched there is no wear on the gears. Next time you are on the road listen to a semi accelerate from a stop, there is no lurching or grinding of gears. They are only using a clutch to start.
I’ve put 250k miles on a Toyota Celica and a million miles on a truck without a transmission or clutch problem.
Try it, you might be surprised.

[icarp]

John, jmc1313
I made a video to introduce an explanation of the concept of double clutching . I have been teaching racing, and restoring racing cars for 47 years , in a wide variety of cars I might ad , from the early 1920's to modern GT and formula cars . How about a Wilson Pre Selector Gear box ? In my last post, I think you missed my acceptance of your point that some racing transmissions love shifting without the clutch . A motorcycle transmission loves to shift as well, without the clutch . I also agree that a syncro trans can be shifted without using the clutch . But choosing to shift the car without using the clutch is going to cause most people trouble . Also I did state it is possible to get your self home with a broken clutch operation .
Your truck trans is designed to be shifted without using the clutch. "designed to be shifted without using the clutch". Not "can be shifted" . I agree that synchronizing the speeds of the gears is key.
I mention that many times in the video

Just stating that some of "your" vehicles can be shifted with out using the clutch might be confusing to the readers . I am trying to appeal to the majority of the readers .

I wrote the Lesson for teaching our "Special Forces" on how to drive a manual trans car . It is part of a lesson plan that is considered a part of the ultimate lesson plan for all of our "Special Forces". It is a 6 day intensive program .
"Man Trans " is 45 minutes of classroom, then we had less than 15 minutes, per student, to teach each student every thing there is to know about driving a manual trans car . I'm sure there were things in the lesson that you were not aware of as well .
15 minutes to become familiar and proficient, with the entire process.

I am just trying to help the Porsche owner become more familiar with the art of shifting
Ian

[MikeD930]

Ian...I never thought about double clutching during upshift. I have yet to became proficient in double clutching including heel/toe while downshifting. Since watching your video I have a better understanding on how to do it properly and I will make an effort to double clutch more often if not every time. Thanks for sharing your knowledge with us about double clutching.

[icarp]

Originally Posted by MikeD930

Ian...I never thought about double clutching during upshift. I have yet to became proficient in double clutching including heel/toe while downshifting. Since watching your video I have a better understanding on how to do it properly and I will make an effort to double clutch more often if not every time. Thanks for sharing your knowledge with us about double clutching.

Mike , thanks for the nice words . Double clutching on an upshift , is for helping a bad or worn syncro . I suggest the practice of double clutching on an upshift as a way to increase the opportunity to develop the skill set , the more you do it, the better you get at it . So double clutch on every shift for a while . Practice slowly.
As with all driving skills , the more you think about them , the better you get.
I try to think of all of my driving skills at some point while I'm driving .
Ian

[alexandervdr]

great video, takes the macho and nonsense out of the double clutching, to replace it with facts, logic and method

[kent olsen]

When my boss bought a Freightliner tractor and trailer (16 speed) to carry the race-car his son and I went out to learn to drive it. Up-down shifting without the clutch was difficult. Sometimes I would just barely hold a little tension on the shifter so I could feel the speed of the gears and slip it into the next gear as I felt it slow down. My biggest problem was slowing for a turn where I needed to drop 2-3 gears. I could never seem to find the right gear and remember times when I had to stop and start over. No one ever suggested I just use the clutch, hmm.

[NY65912]

Many years ago I would drive a 1960 B model Mack oil truck. Very easy to up-shift w/o the clutch.
Always dbl clutched down shifting as it was a crash box. It had an incredibly tight gear box.

Thanks for the video and thanks to Tom for presenting it on Garage Time

Cheers

[911pcars]

Double-clutching on upshifts isn't necessary. The gear ratios decrease during an upshift 1-2-3-4-5, thus engine revs gradually decrease during upshifts. Thus as the engine revs decrease from the previous gear, it will gradually match the revs of the next higher gear selected . You should be able to feel that engagement threshold while holding the lever against the synchro as the revs decrease.

OTOH, reving the engine (in neutral) while double-clutching during a downshift increases the matching revs as each lower gear is selected.

Sherwood

[Lyle O]

I watched the video and read all of these posts, and took my car out to try this. It is not easy changing 45 years of trained muscle memory! I have a lot of practice to do to get even close to feeling comfortable...

[pampadori]

Sherwood, double clutching on the 1 to 2 upshift is the only way my dogs don't grind. I am in need of some 915 work but have a 2nd baby due this month so car is on the back burner, so to speak.
It may not be necessary but it is the only way to get the two shafts in the trans to match speeds and make the shift free from grinds.the falling rpms of the engine won't help do that.

[hitch911]

I too have been practicing as Ian suggests. He mentioned it'll take 3-5 years to get really good at it. Probably spot on, like changing your golf swing. A swing fix may work on the driving range and even on the first tee but how about on the 72nd tee of your club championship with a 1 shot lead? For me to make downshift double clutching instinctive and natural will take many hours of practice. Love the reward of a good shift though and something new to work on. Thanks for the video and sharing your knowledge of shifting fundamentals.

[911pcars]

Originally Posted by pampadori

Sherwood, double clutching on the 1 to 2 upshift is the only way my dogs don't grind. I am in need of some 915 work but have a 2nd baby due this month so car is on the back burner, so to speak.
It may not be necessary but it is the only way to get the two shafts in the trans to match speeds and make the shift free from grinds.the falling rpms of the engine won't help do that.

If you allow engine revs to drop during the shift, the worn synchros will struggle to match revs. Try shifting before the revs drop below the rev zone it would be at the current car speed. If double-clutching helps, the above procedure is essentially equivalent. At the end, do what's necessary to get in gear and minimize add'l wear.

Hitch,
D-clutching is just another driving skill. Not necessary for basic car control, but suggested for better car control and to extend service intervals. How long does it take to master golf, culinary skills, playing an instrument .... or curling? It's a continuous learning process, especially for skills you care about. It's been loosely said that Jack Nicklaus, at his peak, would still hit 500 practice balls a day.

S

[josephvman]

I have no issues with heel/toe in my other cars, but the pedal on my 3.2 make it very difficult. Anyone else struggle with this on their air-cooled car?

[hitch911]

Sherwood, Nicklaus worked very hard and then there's Hogan who said there weren't enough daylight hours in a day to practice all the shots he needed to practice. No substitute for hard work for sure. Will take your advice and find a quiet country road and practice in the higher gears for starters. I feel somewhat duty bound to improve my skills so my carrera benefits too. Fun stuff.

[Alan L]

Great video - well explained.
I had the misfortune some yrs ago to break a clutch cable on my SC. Normally you would think of a lift home for the car. I was only part way in to a long journey in a remote area. I drove it several hundred miles with no clutch - and not flat straight road. Twisty up/down country road and a few towns in between. Used the wide torque band of the 3.0 as much as possible to conserve shifts, and my gearbox - but got to know where the revs needed to be. And with a little pressure on the gear lever you could feel when it wanted to slip in. Those synchro bits in a 901/915 box are $$$expensive.
That box some 10-12 yrs later is still in the car and performing perfectly.
What had happened was the clevis pin holding the fork to the pedal cluster had worn thru. Subsequently, each pedal cluster I have pulled apart has been in bad shape. There are plastic bushes that are usually badly worn, and the clevis pin always has wear also. Something to check. PITA to get to - which is why they don't get checked. I replaced the SC clevis pin with a cut down high tensile bolt. Not sure if it was the right thing to do - but it is still all holding together OK.
Alan

[911pcars]

Originally Posted by josephvman

I have no issues with heel/toe in my other cars, but the pedal on my 3.2 make it very difficult. Anyone else struggle with this on their air-cooled car?

The way the pedals are arranged, it's easier to toe on brake and heel on gas pedal. The gas pedal is typically not on the same, preferred level as the brake, but it can be raised or a block installed to approximate the brake pedal at some applied position. Don't lower the brake pedal. Not recommended to run out of range with brake to spare.

One of the Porsche aftermarket companies has a fully articulated, hinged and turn-buckled gas pedal that should satisfy all manner of foot sizes, angles and bone spur projections.

[Alan L]

Bear in mind you are normally depressing the brake pedal a fair bit when heel/toe on the downshift. It should line up approximately in the area of the gas pedal. I use the ball of my foot on the brake and sort of roll my foot over a bit - using the heel and lower side of the foot on the gas pedal. The top of the gas pedal shouldn't be too far away from the brake position. it maybe a case of adjusting how you are using the foot. Try some alternate techniques. You don't need to reach near the bottom of the gas pedal. Not like normal driving where you rest the heel of the foot on the floor and position over gas pedal.
Alan