What is "Double (D) Clutching"?

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Jostyrostelli

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I hear you only double clutch with non synchro-mesh gearboxes...
Do you also double clutch with old trucks?
 

andyhui01

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what exactly is Double Clutching... I've heard it mentioned in Fast and Furious but I never knew what it meant :(
 

Mischief007

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I double clutch on the downshift since there is no need for the upshift.

Basically, I'm driving in 3rd and want to get to 2nd without the jerking downshift. Clutch goes in, out of 3rd into neutral, clutch pedal goes up, quickly tap the throttle, engage the clutch, into 2nd, and gas pedal. I do this in under 2 seconds now. Going from 5th to 3rd is what I'm still trying to master.

With the older gear boxes you had to do that for the upshift as well or you would be crunching some gears...lol.

I'm still learning heel and toe but can't do it with my current car because the gas pedal is lower than the brake pedal.
 

Jostyrostelli

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Aah Okej! Other word for what I already knew...so if you don't have a synchro-mesh gearbox you still have to double clutch on the way up.
 

Mischief007

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Jostyrostelli said:
Aah Okej! Other word for what I already knew...so if you don't have a synchro-mesh gearbox you still have to double clutch on the way up.
Yes :). Correct. You got it.
 

MXM

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Mischief007 said:
With the older gear boxes you had to do that for the upshift as well or you would be crunching some gears...lol.
Yes, but you shouldn't tap the throttle on upshifting. Because you need less revs than at lower gear.

The idea behind it is to syncronize the spinning mass between clutch and gearbox to be equal with gearbox. You can actually put a gear in without clutch at all, if revs are perfectly matched. I have no idea why the hell they needed it in F&F :lol:
And on downshifting... It's usefull on old cars, but I haven't heard anyone using double-de-clutching while racing. It take too long, so you hardly win any time. Tapping the throttle while clutch is pressed is enough to match engine revs and switch gear smoothly.
 

Mischief007

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MXM said:
Yes, but you shouldn't tap the throttle on upshifting. Because you need less revs than at lower gear.

The idea behind it is to syncronize the spinning mass between clutch and gearbox to be equal with gearbox. You can actually put a gear in without clutch at all, if revs are perfectly matched. I have no idea why the hell they needed it in F&F :lol:
And on downshifting... It's usefull on old cars, but I haven't heard anyone using double-de-clutching while racing. It take too long, so you hardly win any time. Tapping the throttle while clutch is pressed is enough to match engine revs and switch gear smoothly.
true as well. Almost no one uses it anymore. It's a lost art :)
 

Daniel

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It was very popular back in the 70's. Also its kind of important if your on a 2 stroke motorbike, so that you can keep it in the power band.
 

Phix

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When I downshift I Clutch in, neutral, blip throttle, downshift, clutch release. IS that bad? Should I double-clutch when I downshift? Car is a '92 Toyota Paseo.
 

v0od0o

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Some hardcore driving machines don't have synchro-mesh gearboxes, because these waste some power and torque along the way, and if you're driving one of those you'd still need to double clutch.... I think the F40 falls into that category
I found a useful article here: http://www.epinions.com/auto-review-6902-1618F526-3A351631-prod4

Also from personal experience I found out that when changing gears in my friend's citroen xsara at the redline at 6500rpm the gearbox consistently misshifts and needs the revs to drop down a bit before changing which wastes around 2 seconds, I think he can remedy that with double (de)clutching but he dunno how to do it :)
 

Mischief007

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very good read v0od0o.

So I'm actually minimizing the syncro wear on my POS Cavalier even further by re-engaging the clutch in neutral. Good to know. At least I do that automatically now without even thinking about it.

Still need a better vehicle for toe and heel though. Damn. Tried it a few times on the cavalier and I just over brake because the brake is higher than the gas pedal.
 

Phix

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I've been a '88 Cavalier Z24 and the clutch is SOOOOOOO DAMN LONG! I mean, fuck, I actually had to slide myself further into the seat just so I can get the clutch to the damn floor. What the hell is up with that.
 
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I use it (even though I wouldn't need to), but it makes for nice smooth downshifts.
 

Mischief007

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Phix said:
I've been a '88 Cavalier Z24 and the clutch is SOOOOOOO DAMN LONG! I mean, fuck, I actually had to slide myself further into the seat just so I can get the clutch to the damn floor. What the hell is up with that.
I know what you mean. But I only push it all the way in for first and reverse. All the other times I can have it pushed in 5/6th of the way in and still be very smooth. I think the clutch in my Cavalier is still new.
 

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You only have to push the pedal in far enough to disengage the clutch. On most cars it's about half way. On my car it's about 10% in. Means to shift gears i just tap the clutch. It's really, really quick. Just makes my car a total ass in stop/start traffic, but then the 205 always had a grabby clutch.

If you learn to heel/toe correctly, you can shift down gears without using the clutch. I learnt how to do that in my old car (suzuki swift gti). It was truly awful in corners, but had really feely controls, so it was easy to learn in.

Once you can heel/toe effectively without the clutch, you can switch to left foot braking, and forget the clutch altogether (apart from starting/stopping the car). Clutchless shifts are brilliantly fast and smooth, it's really amazing the first few times (the first few times you nail it). :)

Oh, i must point out that you practice left foot braking a lot before you try driving without the clutch, it takes a while to unlearn to dip the left foot between gears (and causing you to headbutt the windscreen).
 

andyhui01

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so this is basically the same as heel & toe braking... BTW can't you just hold the clutch and tap the throttle while shifting... I don't think it makes a difference
 

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^ As I said before, this way spining mass between clutch and gearbox will not be syncronized with gearbox. Think of it as simplified scheme of 3 parts:
engine--||----[ ]---wheels. Where || represents the clutch and [ ] gearbox. Use your imagination :)
You press the clutch, tap accelerator, so engine is reving correctly, but now you must put in a lower gear. The |---[ part is still spinning too slowly for that gear and it doesn't work smoothly.
But if you double-clutch so that you release the clutch pedal on neutral, reving the whole engine--||----[ part, so it's perfectly syncronised with rest: ]---wheels, you can put in gear very smoothly. If perfectly done, you don't even have to press the clutch second time. But it safer to do it, unless you're very precise.

I hope that wasn't too confusing.
 

Mischief007

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Cubits said:
You only have to push the pedal in far enough to disengage the clutch. On most cars it's about half way. On my car it's about 10% in. Means to shift gears i just tap the clutch. It's really, really quick. Just makes my car a total ass in stop/start traffic, but then the 205 always had a grabby clutch.

If you learn to heel/toe correctly, you can shift down gears without using the clutch. I learnt how to do that in my old car (suzuki swift gti). It was truly awful in corners, but had really feely controls, so it was easy to learn in.

Once you can heel/toe effectively without the clutch, you can switch to left foot braking, and forget the clutch altogether (apart from starting/stopping the car). Clutchless shifts are brilliantly fast and smooth, it's really amazing the first few times (the first few times you nail it). :)

Oh, i must point out that you practice left foot braking a lot before you try driving without the clutch, it takes a while to unlearn to dip the left foot between gears (and causing you to headbutt the windscreen).
I've always been afraid to try clutchless shifting. Maybe when I get rid of the car, I'll kill it and leave it to the junkyard...:)...lol
 
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