Double Clutching?

Question

Am i right in thinking double clucthing is using the clutch to disengage gearing to neutral, coming off the clutch and then depressing it again to engage the gear so that you can apply the power quicker?

Answer 1

yes i think your are right

Answer 2

It is for gearboxes without synchromesh, some 1980s cars had no synchro on 1st so it is not that ancient.
Basically when changing down you depress the clutch move the gearlever to neutral "blip" the accelerator to speed up the gearbox input shaft to match the speed of the gear to be engaged and then disengage the clutch and select the gear, releasing the clutch again, this should result in a quiet change, this is not usually nescessary when changing up,
Synchromesh does this speed matching automatically with out any need to double declutch, but synchromesh will slow down racing speed changes , which is why racing cars and motorbikes have non synchro boxes.

Answer 3

yes

i was taught it as "double de-clutching"

But the purpose wasn't about getting back on the gas quicker. It slows you down. The deal was that in old cars, changing gears involved engaging a couple of cogs with each other while they were spinning at different speeds.

Crunch.

So instead of crunch, you double de-clutch, and that means the cogs aren't so wildly out of synch with each other when they meet.

Synchro-mesh was invented to get round that problem. What happens is that as you change gear a little metal collar slips onto a ring on the driven shaft (if I have it the right way round) and gets it in synch with the drive without actually applying any torque, just before the teeth of the two cogs mesh together. At that point they're spinning in synch so no crunch. Then you take your foot off the clutch and torque is applied through the teeth.

So with full synchromesh, no need to double declutch.

Some older cars still don't have synchromesh on reverse, hence the crunch you often hear.

Answer 4

When a transmission has no means of synchronizing the gears during a shift, there must be a means of synchronizing the speed of the input shaft and drive gear with the output gear and shaft.
The purpose is to allow the speeds to match closely enough to allow engaging gears without the "crash" or "raking" or "grinding" that would result without the manual synchronizing of the gears.
On modern transmissions, there is a mechanical means for this necessity, and the term is "synchromesh".
OLD equipment and most "big-rigs" still require the double clutching for both up-shifting as well as down-shifting.

For a clear discussion of the matter, go here------->

http://en.wikipedia.org/wiki/Double_clutch

Good Luck

Answer 5

It's actually called double de-clutching and is not neccessary with modern cars that have syncromesh gearboxes.. it was needed in older cars that had what was know as a crash gearbox. It's technical so I won't go into greater detail.
But you are right, the clutch goes down, gear disengaged, clutch comes off, clutch goes down a gain and a new gear selected.
All this done in quick time, there was a reason for it, ask if you really do want to know.

Answer 6

Double the clutch.

I haven't heard that it a while.

No you will not be able to apply the power quicker that way. in fact you may even end up doing some serious damage if you get the timing wrong. Also it will slow you down

The last time I had to double the clutch was well over 20 years ago and that was on a nasty buggered up old tractor which was a total ***** to drive.

Answer 7

This is from an old gimmer I drove when I was 15 years old a 3ton lorry and the only way to change gear was to double the clutch. But now with modern vehicles it will not make any difference to power at all.

Answer 8

It's proper name is 'double de-clutching' and it is what you had to do before they invented synchromesh. It was necessary for cars and lorries in the old days (even before my time!) but I did have an old horsebox many years ago which was a converted removal lorry and I sometimes had to do it with that. My Dad showed me how to do it!
It's a useful thing to know how to do as it can get you out of trouble if your clutch or gear box go wrong.

Answer 9

If you double declutch you first move the gear stick into neutral, lift the clutch and rev the engine slightly then depress the clutch and move into a lower gear. Usually done on very old cars to try and equalise engine revs when changing to a lower gear. you do not need to do it on modern cars.

Answer 10

In the 50 s there used to be what was known as a crash gear box with no clutch to change up gear you would let the revs go down and slip up the gear to go down you would hit the acc to rev uo and slip up.with the advent of syncromesh as in the clutch you dont have to do this.you can still dtc in syncro using the old method by the revs with no use of the clutch or even without doubeling

Answer 11

nearly right ,, but the idea is to rev the engine while out of gear just before you put it back into gear ..a good way in fact to drive if your syncromesh has worn ,, and it crunches ,,its also quite good if you can anticipate the the engine revs ,, and change up or down ,, without useing the clutch at all..the top drivers used to call it toe and heel because they only used one foot to do both at the same time