TheSamba.com :: View topic - The Art of Double-Clutching

Mon Mar 01, 2010 1:05 am

The updated version, five luxurious pages where the original in 2004 was but one.

Please read through the whole thang and see if there is sufficient flow that you are "insightfulized" by the end. This is my first computer-generated font + Paint® drawing assistance. It takes three times longer than straight drawing, but with no paper to crumple up and throw away every time I mis-print a word, the time savings is ENORMOUSLY . . . negligible.
Colin

Mon Mar 01, 2010 1:42 am

That is fantastic!

Thanks Amskeptic. :)

Mon Mar 01, 2010 2:15 am

Nice read but double clutching was not invented to put less ware on your syncho rings as a matter of fact it will ware them way qwiker if you don't do it just right and most don't! Double clutching was for tranys (mostly in big trucks) with no synchos at all. Synchos were invented so you didn't have to do that. When you go to ingage a gear the syncho stops the gear for you so you can go into that gear, If you try to double clutch you will push up against the syncho it trys to stop the gear but the gear is still powered and just ware's it out unless you are right on the money. Beleave me double clutching is a fine art most can not master I have been a trucker in the past and it is very tuff to get right. I had a customer last year that did that in a syncro vanagon his trany was rebuilt and it was wasted in no time. When the trany came to me I couldn't figure out why all the synchos were wore all the way down and not working at all shot all the way. So I rebuilt it and talked to the guy trying to find out what happened he said he drives it double clutching I said you just voided the warranty. Nice wright up and graghics but false info. Oh and by the way using your clutch twice to do the job each time put more ware on clutch parts also. heres some food for thought
http://en.wikipedia.org/wiki/Double_clutch

Mon Mar 01, 2010 7:42 am

bigbore wrote: Oh and by the way using your clutch twice to do the job each time put more ware on clutch parts also. heres some food for thought
http://en.wikipedia.org/wiki/Double_clutch
wikipedia wrote: Double clutching can minimize this clutch plate wear by encouraging matching of engine and transmission RPMs before the clutch plates are engaged.
You may want to consider reading the whole page before linking to it.

Colin-This write up is fantastic. I was impressed with your old one and it is put to shame by this new one!

Phil

Mon Mar 01, 2010 7:45 am

well color me skeptical, or is it colour? Sorry, had to.

bigbore: double clutching was probably also invented for early VWs. they didn't always have synchros AFAIK. when you say it wears everything faster, do you mean if they "double-clutch" without using the clutch? Like what you do when the clutch cable breaks, or do you mean that even if you go
gear
clutch in
netural
clutchout
clutch in
gear

you will still wear it extra?

transmissions are fun, I have a hell of a lot of learing to do.

Mon Mar 01, 2010 8:00 am

** Threads removed **

C'mon kids, we don't need the spelling stuff in this thread.

Mon Mar 01, 2010 8:29 am

I can't offer any scientific data on what is more efficient or what wears less. I can only say that when I double clutch on downshifts the shift seems smoother and the syncros seem to work less. Plus it's fun to do! Along with heel-and-toe! :D

Mon Mar 01, 2010 8:32 am

I drove trucks also and they have non-synchro transmissions hence the need for double clutching. Double clutching with a synchronized tranny is wasted effort and not needed. Floating gears is a technique of shifting without using the clutch, matching road speed with engine speed but that is a entirely different topic. 8) :bay_red:

Mon Mar 01, 2010 8:36 am

wampe wrote: Floating gears is a technique of shifting without using the clutch, matching road speed with engine speed but that is a entirely different topic. 8) :bay_red:

really? the technique is exactly the same, aside from knowing how to rev the engine to "unlaod" the trans with the thing still in gear. I taught myself how to do this, in case of emergency, and damn did it come in handy. if you know how to double clutch, you know how to drive w/ a broken clutch cable or throw out arm.

practice this, and you will make it home (or 3 hours to a concert no one wanted to miss!)

Mon Mar 01, 2010 8:38 am

Floating gears has been much harder for me to learn. It seems to require that you have a really good feel for engine speeds. I still can't get the technique down, and I'm afraid I will do damage if I keep trying to learn it. But I agree that when it does work it's a great feeling.

Mon Mar 01, 2010 8:40 am

learning it is deffinatly terrifiying. I also taught myself how to drive stick, so I do most everything by feel. learn to double clutch first, then to float gears, is my reccomendation to anyone listening. I assume you've got it by now

did i mention how much a tach helps this process?

Mon Mar 01, 2010 8:49 am

Great article Colin! Thanks for taking the time to do this!

But it is winter, and your fresh air vents are open!.? :lol:

Mon Mar 01, 2010 8:59 am

Nice...
I learned to drive without a clutch because my first VW broke the throw out rod..

Plus I had a 52 chevy truck that I named bitch, because she always wanted to grind third unless you double clutched...

Remember the old dodge hemi trucks? Automatic after first, but still had a clutch.

Our 51 dodge truck had to be double clutched...

VW's are easy to drive without a clutch, but starting it in first gear has to be hard on the starter :)

Mon Mar 01, 2010 9:01 am

or the passengers, depending on battery condition.

Mon Mar 01, 2010 9:05 am

79SuperVert wrote: Floating gears has been much harder for me to learn. It seems to require that you have a really good feel for engine speeds. I still can't get the technique down, and I'm afraid I will do damage if I keep trying to learn it. But I agree that when it does work it's a great feeling.

Do you have a tachometer? The key to floating gears is to keep the engine at a specific RPM while shifting. Myself, I prefer automatic transmissions. I did enough shifting when I drove trucks. :D :bay_red:

Mon Mar 01, 2010 9:13 am

Emeritusx wrote: Nice...
I learned to drive without a clutch because my first VW broke the throw out rod..

Plus I had a 52 chevy truck that I named bitch, because she always wanted to grind third unless you double clutched...

Remember the old dodge hemi trucks? Automatic after first, but still had a clutch.

Our 51 dodge truck had to be double clutched...

VW's are easy to drive without a clutch, but starting it in first gear has to be hard on the starter :)

Sounds like the synchros went out in your Chevy truck. A lot of old vehicles needed to be double clutched but those days are gone. I depress the clutch once when I shift the bus, less wear and tear on the drive train. :D :bay_red:

Mon Mar 01, 2010 9:39 am

wampe wrote: 79SuperVert wrote: Floating gears has been much harder for me to learn. It seems to require that you have a really good feel for engine speeds. I still can't get the technique down, and I'm afraid I will do damage if I keep trying to learn it. But I agree that when it does work it's a great feeling.

Do you have a tachometer? The key to floating gears is to keep the engine at a specific RPM while shifting. Myself, I prefer automatic transmissions. I did enough shifting when I drove trucks. :D :bay_red:

No tach. But I can see how it would be great as a temporary fix until I got the hang of listening to the engine.

Mon Mar 01, 2010 9:45 am

It makes easy sense that depressing the clutch twice for every shift would wear the pedal/ lever mechanism.

Couldn't you just keep the clutch in? - or does releasing it while it's in neutral reset something? I can't see how revving it in neutral is different from revving it with the clutch in? -Then you'd only be pushing the clutch in once and you'd get the same result, as long as your rpms match what the input shaft of the tranny is revolving at? -this would be just like gear floating, just with use of the clutch as a safety?

-Like, if you're shifting properly, shouldn't this be your goal every time, to bring rpm near input shaft speed as you judge it, then release the clutch (feather) to engage? Is the first clutch push (or release I should say) just an extra step?

Mon Mar 01, 2010 9:52 am

it takes no effort to spin the input shaft, thast why you drop the cluch in neutral. when you shift you are meshing the input shaft with the output. in simplified terms. By having the clutch engaged when you do this, you know the speed of the input shaft is the same as that of the engine. otherwise you have three speeds todeal with , inputs haft, engine, and output. if you have the clutch engaged, you know the speed of the input shaft, and if you know how fast you are rolling, you know the speed of the output, this allows you to bypass the syncrhos.

Mon Mar 01, 2010 11:39 am

Quote: It makes easy sense that depressing the clutch twice for every shift would wear the pedal/ lever mechanism.

the throwout bearing is what gets the unnecessary wear.