Double Clutching Article

[m5child]

I've found this article while browsing the web... It talks about double clutching while down shifting in emergency situations... I haven't personally heard of this before and wonder if you have any comments and explain it to me why double clutching can help you while downshifting... thanks

http://www.wisegeek.com/what-is-double-clutching.htm

[Niko_Fx]

I'm always granny shifting, not double clutching like I should

[NSXType-R]

Talking about downshifting, I heard that downshifting is bad because it strains the engine. My dad does it all the time though. Is it true that it's bad? The downshifting my dad does is not a high RPM downshift (more like 2K to 4K, not much more) and it's more like an engine braking thing.

[Jack_Bauer]

I've found this article while browsing the web... It talks about double clutching while down shifting in emergency situations... I haven't personally heard of this before and wonder if you have any comments and explain it to me why double clutching can help you while downshifting... thanks

That article explains the benefits of double declutching in emergency situations pretty well I think. Essentially, if you're on a slippery surface and need to slow down then applying force through the brake pads and discs creates a risk of locking up the wheels. Then you're into a skid and you're effectively out of control of the vehicle. Double declutch or heel and toe downshifting allows you to utilise the braking force from the engine and drive train, meaning you have to put less force through the brake pedal and there is less chance of a lock-up. To be honest though, in a new and modern car with all the fancy ABS, ESP, EBD etc there is probably not a lot of need for double declutching as the electronic safety nets are there to get you out of tricky situations like brake lock ups. It is only in cars without ABS that this technique is potentially useful for emergency situations.

Learning advanced techniques like that can never be a bad thing though, it's always worthwhile. Even if you never strictly HAVE to use it, it's good to know that you have developed the skills and awareness to be able to avoid such tricky situations. Plus as the article explains double declutching can avoid wear and tear of the gearbox internals, which is always nice if you have an older sort of car. In a newer car I'd imagine the gearbox would be robust enough so that it would take hundreds of thousands of miles before the synchros are knackered through normal "granny" shifting, unless you give your gearbox and car some SERIOUS abuse. Also heel and toe double devlutching helps greatly with smoothness in your driving, especially with downshifting when you're driving at decent pace. It's almost a necessity if you're gonna do any track driving.

On the right hand side of this page there is a good little picture tutorial of heel and toe downshifting for you, although that is only single declutching - http://www.turnfast.com/tech_driving..._heeltoe.shtml

I tried to find a video of someone heel and toeing on Youtube for you, but all I got was tapdancing moves and foot fetish vids.

[fa22_raptor]

I have a great video of someone double declutching and heel and toeing. However, it's very big and I don't know how I would show it to you guys.

[Gardin]

It's required in cars like my FIAT 500 with unsyncronized gearbox. And it's very small and with the engine in the back you don't want the rear end to brake loose, unless you are Schumacher, or just plain stupid. I have tried a little on loose surfaces and it's funny if you want it and are prepared, but if not it will scare you senseless!
If you drive new cars with all sort of electronics this is useless information, but if you drive old cars with unsynchronized gearboxes, you need to learn this...

[Jack_Bauer]

I have a great video of someone double declutching and heel and toeing. However, it's very big and I don't know how I would show it to you guys.

How big is very big? Too big to be put up at www.youtube.com or google vids? Not sure if they have upload size limits there, but I've seen some pretty huge vids on there. Give it a go, I'd lilke to see it.

[m5child]

Thanks Jack_Bauer

I understand the basic ideas of the article, although I still can't visualize in my head how it will work out... so if i need to downshift in an emergency situation i take the tranny out of gear, leave it in neutral (first clutch)... then the article mentions something to the effect of raising the revs a bit to keep the engine and the tranny at the same revs and then re-engaging the lower gear (second clutch)... I see the whole point of trying to match the revs of the tranny and of the engine in order to use the engine's inertia to slow the car... but I still don't see how that would actually happen... Maybe i need to do and try it myself...

Thanks!

[magracer]

Thanks Jack_Bauer

I understand the basic ideas of the article, although I still can't visualize in my head how it will work out... so if i need to downshift in an emergency situation i take the tranny out of gear, leave it in neutral (first clutch)... then the article mentions something to the effect of raising the revs a bit to keep the engine and the tranny at the same revs and then re-engaging the lower gear (second clutch)... I see the whole point of trying to match the revs of the tranny and of the engine in order to use the engine's inertia to slow the car... but I still don't see how that would actually happen... Maybe i need to do and try it myself...

Thanks!

As has been said before, double declutching is not requied on most modern cars. Toe and heel should be quicker than double declutching, and provide the same benefits (it can be fun too). I for one, use it on everyday driving.

[VtecMini]

On the right hand side of this page there is a good little picture tutorial of heel and toe downshifting for you, although that is only single declutching - http://www.turnfast.com/tech_driving..._heeltoe.shtml

That's interesting. I was told that heel and toe is actually not done with the heel at all, but the far right hand side of the ball of the foot. That's how I've always done it, anyway.

It's a damn sight easier on the ankle, I know that much.

[magracer]

That's interesting. I was told that heel and toe is actually not done with the heel at all, but the far right hand side of the ball of the foot. That's how I've always done it, anyway.

It's a damn sight easier on the ankle, I know that much.

That's correct, the name is decieving... it might be because it's done with the part where the ball meets the heel (i.e side)...

[KnifeEdge_2K1]

Talking about downshifting, I heard that downshifting is bad because it strains the engine. My dad does it all the time though. Is it true that it's bad? The downshifting my dad does is not a high RPM downshift (more like 2K to 4K, not much more) and it's more like an engine braking thing.

it is if you do it bad, the theory behind downshifting to slow down is to use the friction of the engine's internal parts instead of the brakes

i have to repeat ... the ENGINE'S internal parts, not the transmission's

the friction of the engine's parts are always the same (or differ by negligible amounts) but the gear ratios have a multiplying effect, this is why slowing down in 5th by coasting isnt as good as slowing down in 4th while coasting

anyways back to double clutching, the whole point of this technique is to rev match both the engine adn transmission gears prior to the actual downshift, granny shifting means you only rev match the engine, but the internal gears are all moving at the wrong speed, when you shift like this, the syncros must take up the slack and wear down as a result, modern sycro's are really good and will last much longer then other parts of the car thus making double clutching unneccesary in most situations, but most people still want to know what it is, and want to learn the technique

[KnifeEdge_2K1]

As has been said before, double declutching is not requied on most modern cars. Toe and heel should be quicker than double declutching, and provide the same benefits (it can be fun too). I for one, use it on everyday driving.

heel and toe and double clutching are 2 different techniques but can be combined

heel toe is a technique which provides maximum decelleration in anticipation of accelerating out at the end

double clutching is a technique to minimize strain on the tranny internals

both techniques deal with slowing down and downshifting, but are different in nature and purpose

[Egg Nog]

I'm always granny shifting, not double clutching like I should

Awesome, that totally made my day

[clutch-monkey]

pretty interesting article, good find