Double Clutching?

[Griffo]

I've come across a phrase used in some motoring articles and forum posts where people have made reference to double clutching when driving hard.

Can anyone help me out and explain what the driver is doing when double clutching?

Thanks,

Griffo.


Migration info. Legacy thread was 17632

 

[Jamie Summers]

It's a racing term, used in conjunction with heeling and toeing. The idea is that by blipping the throttle on a down change (whilst the gears are disengaged), you bring the engine up to the correct speed for the gear you are changing down to relative to your speed over the ground, resulting in a smoother change. It used to be essential in the days before synchromeshes (these do the job for you !) - racing cars with straight cut gears still need to use this technique.

It's explained quite neatly here .

http://www.tcsracing.org/doubledeclutching.htm

Hope that helps !

Jamie


Migration info. Legacy thread was 17633

 

[Carrera]

Do you mean double de-clutch? I think that means releasing the clutch after changing out of gear, while in neutral, then depress clutch again to get in another gear. That's what you needed to do before synchromesh days. The purpose of that is to match the speed of the gears to engage. With synchromesh I don't really see the point of doing it unless you really want to look after your gears. I'm not sure why you need to do it when driving hard 'cos it takes so long to change gear this way. Far commoner to heel-toe and blip the throttle to match the speed of engine and gears.

Have I just made you even more confused?


Migration info. Legacy thread was 17634

 

[bosch]

double de-clutching does make for smoother gearchanges and saves the sycnromesh when you're using high revs. It also makes a great sound (patricularly in tunnels)! It's only relevant on down changes, and as Jamie & Mick says its used to match gear speeds.

Migration info. Legacy thread was 17637

 

[manek]

Double de-clutching can help reduce the tendency of the rear wheels to lose grip on slippery surfaces if you change down at high speeds, which can lead to a loss of control. It also saves wear on the transmission since it doesn't have to absorb the shock as the road wheels increase the engine's speed.

But mainly, it sounds good...


Migration info. Legacy thread was 17638

 

[Pickled Piper]

Double declutching or double clutching makes for smoother down changes even if you have got good syncromesh. It's one of those "old school" driving techniques that is not really taught any more.

If you brake at the ame time as double declutching then you are heel and toeing.

PP






Migration info. Legacy thread was 17642

 

[WillD]

The sound ..... the sound....... I was taught 11 years ago by John Lyon in a Caterham 7 side exit exhaust. Now with the 911's ..... it's makes me smile everytime...

Migration info. Legacy thread was 17644

 

[Griffo]

Thanks for all the info. Time to find a long tunnel and try it out for my self !

Migration info. Legacy thread was 17646

 

[graham_mitchell]

I don't think anyone got it right (though Butzi was closest). People seem to be talking about blipping the throttle to match revs between changes, which is of course good practice.

Double clutching is when you declutch, then select neutral gear, then release the clutch, then rev the engine to bring parts of the gearbox up to speed, then declutch, then select the new gear, blip the throttle again, then release the clucth. Hence 'double clutch'. It was necessary on very old gearboxes but frankly I doubt it serves any useful purpose in these days of synchros.

Migration info. Legacy thread was 17687

 

[luke]

I've been having lots of fun practicing this since reading the link suggested by Jamie in the second post on this thread (very good btw)...

If you just blip the throttle with the clutch peddle depressed, the engine doen't hold on the higher revs anything like as long as if you blip the throttle with the gear box in neutral and the clutch peddle released - which makes the double clutch method much more effective

Haven't found a clear enough piece of road to try adding heel and toeing to the equation, and, to be honest, doubt if I've got the co-ordination / double jointed ankle it feels like I need to pull this off


Migration info. Legacy thread was 17752