Double declutching
Discussion
Chris71 said:
Hi,
Can someone explain exactly how you should double declutch on a down change. As I udnerstand it, you
Am I really double declutching that way, or is it just leaving it to the syncromesh?
The second way you might as well not bother double-declutching - you're simply downshifting and matching the revs as you let the clutch back in.Can someone explain exactly how you should double declutch on a down change. As I udnerstand it, you
- clutch down
- into nuetral and clutch back up, so you've properly 'engaged' neutral
- raise the revs to spin up the layshaft
- clutch down
- back into (lower) gear and clutch up again
Am I really double declutching that way, or is it just leaving it to the syncromesh?
As other posters have said, it's all about timing. You should be able to down shift by blipping the throttle in neutral without using the clutch at all - try that a few times (in someone else's company car!) and you soon learn to get the timing right. Pop the lever into neutral as you come off the gas, blip, then, if you get it right, it should glide effortlessly into the next gear down.
I double declutch when I'm (say) changing down on the approach to an A road bend, where I don't want to reduce speed, but do want to be in a lower gear for control purposes. I did this on a defensive driving day at work, and the instructor said it was the first time he'd ever seen anyone do it without being asked, so it must be pretty rare these days.
RobM77 said:
I've often gone against the grain and received criticism on this forum by suggesting that it is important to always be as far away from the limit of adhesion as possible when driving on the road. Most advanced drivers on here seem to advocate doing what you want so long as you don't breach the limit of adhesion.
I think that minimising the forces on the vehicle and the demands you place on the vehicle are aims that most advanced drivers will share. I'd suggest 'usually' instead of 'always' though. There are very occasionally situations where it's desirable or even necessary to approach or exceed the limit of adhesion. These are pretty exceptional situations though.Deva Link said:
I double declutch when I'm (say) changing down on the approach to an A road bend, where I don't want to reduce speed, but do want to be in a lower gear for control purposes. I did this on a defensive driving day at work, and the instructor said it was the first time he'd ever seen anyone do it without being asked, so it must be pretty rare these days.
Was the instructor specifically congratulating you on the double-declutch or just the blip as you changed gear?Bert
Interestingly the double-declutch to help the synchro has different timing than a blip to raise the revs on the downchange.
The "double-declutch to help the synchro" approach has to have the blip when the clutch is up to raise the revs on the input shaft. You then put the clutch down to change gear. If it is a slow gearchange which is likley on an old/knackered synchroed car, you can actually lose the revs for the rev match and indeed go on to blip again.
The blip just to raise the revs can happen later in the process as the clutch doesn't have to be up and then be put down again. I have had some success teaching youngsters to blip by getting them to do it as they select the lower gear. I say "imagine you have to blip the throttle as you feel the resistance on the gear stick going through the gate into gear". Works a treat!
Bert
The "double-declutch to help the synchro" approach has to have the blip when the clutch is up to raise the revs on the input shaft. You then put the clutch down to change gear. If it is a slow gearchange which is likley on an old/knackered synchroed car, you can actually lose the revs for the rev match and indeed go on to blip again.
The blip just to raise the revs can happen later in the process as the clutch doesn't have to be up and then be put down again. I have had some success teaching youngsters to blip by getting them to do it as they select the lower gear. I say "imagine you have to blip the throttle as you feel the resistance on the gear stick going through the gate into gear". Works a treat!
Bert
RobM77 said:
GreenV8S said:
Slowly Slowly said:
you can't mean blip the throttle with your foot on the clutch, please don't tell me you mean that.
I mean that. Tap in "single declutch", nothing comes up. Tap in double declutch and you get loads, I rest my case.................
I mean Youtube of course not Google.
http://www.youtube.com/results?search_query=single...
Edited by Slowly Slowly on Friday 13th July 19:05
BertBert said:
Deva Link said:
I double declutch when I'm (say) changing down on the approach to an A road bend, where I don't want to reduce speed, but do want to be in a lower gear for control purposes. I did this on a defensive driving day at work, and the instructor said it was the first time he'd ever seen anyone do it without being asked, so it must be pretty rare these days.
Was the instructor specifically congratulating you on the double-declutch or just the blip as you changed gear?Bert
that's because there is no such phrase as single-declutch. Just called heal n toeing.
If you watch Mr Vergers at work here....
http://www.youtube.com/watch?v=xTFRihT84Hs
You can see when he does a single downchange that there is no double-declutching going on!
Illustrated in a slightly slower yank tank here...
http://www.youtube.com/watch?v=ihCgxQnex5Q
Bert
If you watch Mr Vergers at work here....
http://www.youtube.com/watch?v=xTFRihT84Hs
You can see when he does a single downchange that there is no double-declutching going on!
Illustrated in a slightly slower yank tank here...
http://www.youtube.com/watch?v=ihCgxQnex5Q
Bert
Chris71 said:
Hi,
Can someone explain exactly how you should double declutch on a down change. As I udnerstand it, you
Am I really double declutching that way, or is it just leaving it to the syncromesh?
Once you've raised the revs to spin up the layshaft hold them there until the gear change is completed. The revs are already where you want them for matching the engine speed to the drivetrain. There is no point in letting them drop only to bring them back up a second time. This means keeping the throttle open just right, a little tricky, but probably smoother once perfected.Can someone explain exactly how you should double declutch on a down change. As I udnerstand it, you
- clutch down
- into nuetral and clutch back up, so you've properly 'engaged' neutral
- raise the revs to spin up the layshaft
- clutch down
- back into (lower) gear and clutch up again
Am I really double declutching that way, or is it just leaving it to the syncromesh?
When the clutch goes in the second time the spun up layshaft starts slowing down, so you want the gear selected reasonably quickly, otherwise the syncromesh is going to have to spin it up again. The clutch can then come out at your leisure. No haste is needed since you are holding the revs constant with the throttle.
The next step is to do all of the above two or three times while braking heavily .
GreenV8S said:
BertBert said:
that's because there is no such phrase as single-declutch.
Agreed.BertBert said:
Just called heal n toeing.
No, they're completely different techniques, which may be used separately or together.RobM77 said:
GreenV8S said:
BertBert said:
that's because there is no such phrase as single-declutch.
Agreed.BertBert said:
Just called heal n toeing.
No, they're completely different techniques, which may be used separately or together.GreenV8S said:
BertBert said:
that's because there is no such phrase as single-declutch.
Agreed.BertBert said:
Just called heal n toeing.
No, they're completely different techniques, which may be used separately or together.Bert
boxerTen said:
The next step is to do all of the above two or three times while braking heavily
That's why the raising of the revs by a blip is done when braking. It is extremely hard to maintain constant (raised) revs at the same time as braking (heavily). That's why the heel n toe uses a blip which is possible for mortals to do! Then you use timing of the gear and clutch to catch the revs at the right point.Bert
vonhosen said:
RobM77 said:
GreenV8S said:
BertBert said:
that's because there is no such phrase as single-declutch.
Agreed.BertBert said:
Just called heal n toeing.
No, they're completely different techniques, which may be used separately or together.RobM77 said:
vonhosen said:
RobM77 said:
GreenV8S said:
BertBert said:
that's because there is no such phrase as single-declutch.
Agreed.BertBert said:
Just called heal n toeing.
No, they're completely different techniques, which may be used separately or together.Gassing Station | Advanced Driving | Top of Page | What's New | My Stuff