Double de-clutching

[tonyp]

Now, lets guess - Your great aunt's Austin Mini Clubman (li'l woody) automatic .....

[Lowtus]

Ha ha - the sort of cars I've had that had no synchro on 1st - you'd be stationary anyway when you needed to get to that gear (think A35, A40, old Landy stuff etc. You know, going up Hardnott pass in 2nd, revs dropping woefully, at the last gasp you swap into 1st, engine roaring lustily (ahem) doing all of - err 3 mph.

Yup, that's how I learnt the double-declutching trade. Completely outdated today, thank goodness!

[andydclements]

Now, lets guess - Your great aunt's Austin Mini Clubman (li'l woody) automatic .....

Oh so close, yet not the right shape at the back , and a different brand / badge.

One of only a few hundred in that model/ mark.

one of even few as it's auto.

Riley Elf mk3.

For those not so sad, it's like a mini, but it has a boot that looks like it's bigger cars (1100 of the time), and a different front style, and "luxury" half leather seats, carpets, wood trim, a glove box and wind up windows, and it came out before it's sister mini mk3.

Andy

[M Blur]

It's a noble art

On the road I don't practice any heel toe or double-clutching anymore.. it really isn't needed unless the clutch/box is weak to the power/rpm... I'm not a fan of heel toe for road either but it does make a more enjoyable drive. Many pedal boxes these days are frankly ill suited to decent heel toe and often the pedals are not at the right stops/heights. Also you need if you delierately cover with your right foot then that does tend to get in the way of making effective emergency stops. Also the iam now practices block changing with only one gear change below the point the revs are still laoding the trans.

also some folks downchange a number of times and that really doesn't make any sense bar for the hell of it. On track it's the only way to perform maximum (threshold) braking but that's no neccessary or advisable on the road. If you brake soon enough on the road then there is no need to heel toe to match revs.

When I was on track I experimented with left foot - flicking both feet from the braking phase into turn in (especially with some trail) is pretty tricky.. easier to perform if you set up the foot to conventionally brake then flick both feet right.. but maybe it'll come with practice.

I'd agree the point about smoothness between pedals but that doesn't neccessarily mean heel toe or double clutching.. often I've been in a car with someone and their efforts have caused more jerkiness than anything else.

I found the standard box in the Esprit too narrow and the pedals at the wrong stops.. I've had a proper floor mounted assembly put in so I can nail the heel toe better.

Running a 2-way for the first time what I've yet to find out is if the deceleration through the lsd will have an adverse response to de-clutch but either way I generally avoid double-clutching so to reduce the time in neutral..

Maybe one day I'll sufficiently practoce so it feels more natural to use more often.. driving an auto day in day out doesn't help mind..

Jon

www.iam.org.uk

Re Steve McQueen.. thought it may have been a dog box and he was loading the gear ring then crashing the upchange with a very small jab of clutch (prb easiest done 3-4th).. as you say I can't believe the trans/fly coudl be that heavy bu then maybe any rpm off cam was too much for SM.. I've heard very similar upshifts in classic 60s-70s racing, especially yank v8s... that or it's sth to do with the box itself maybe...?

[Autocross7]

I tend to throttle blip down in the Esprit, double declutch the Austin Healey, and realy do not do anything but shift up if I am going up the gears. If anything, I'll let the revs drop a bit for the change up on any car. I'll double declutch the Esprit in cases where the guy in front of cannot seem to figure out what the hell he is doing or going to do... then I am in neutral anyway - poised for the brake or the spot chance pass his dumb cell phone talking lip stick applying butt as soon as possible. all the while hoping I do not get rear ended by the guy in back also doing anything but actually pay attention and drive. If I am stopping I just select neutral and brake.

In the traffic here you'd find your self constantly changing down due to the fact that those who are inevitably in front of you cannot drive at all. Very frustrating to be sure. Two cars back at the light, 45 seconds go by before the first guy even moves on green, then 2-3 car lengths before the second guy moves... then you - off into 1st.... 2nd......... 3rd........<<< WTF??? The guy in front is braking on a straight with not one place to turn anywhere in sight!!! And the guy right in front of you needs to move into the left lans and match the first guys speed??? You are now doing 35mph in 50mph zone!

So, into neutral... 3rd.... 4th... no wait - back to 3rd... OPEN SPOT 2ND.... to the floor, 3rd to the floor.... (turbo gets a chance to actually spin here)... and into 4th - just in time for the next idot riding in the left lane with his right turn signal running since he left home yesterday!

Cameron

Edited February 15, 2008 by Autocross7

[neal]

Personally I don't DDC in the true sense by shifting into neutral to match the input and output shafts of the gearbox before shifting into the target gear. On a modern box it's just too cumbersome and unnecessary. Though I don't skip out gears. So if I was changing from fifth to second it would go: clutch in, four, third, second, clutch out. That way each syncho does its share of the work.

But I do always match the engine revs to the the road speed in the target gear before popping the clutch - makes for a much smoother shift which can otherwise unbalance the car (particularly on the track where it could cause the back to step out).

Upshifts are pretty easy: before popping the clutch 1>2 requires a slight pause, 2>3 and 3>4 can be done straight away, 4>5 requires a slight blip of the throttle.

Downshifts require a blip of varying amounts - easy if you're cruising, more tricky if you're braking at the same time. With size 11 feet I find it easier to twist my right foot with it covering both brake and throttle. But it is very satisfying if you get it right when braking hard for a corner on the track. No jerk as you pop the clutch and no pause before you're back on a steady throttle for the turn in. Everything should be smooth from beginning braking to going through the corner - though the ABS can sometimes throw a spanner in the works!

Edited February 14, 2008 by neal

[Vulcan Grey]

Though I don't skip out gears. So if I was changing from fifth to second it would go: clutch in, four, third, second, clutch out. That way each syncho does its share of the work.

Hrm...

The idea behind double clutching is that unless the clutch pedal is released the throttle blip will not actually speed up the synchros, it only raises engine speed to about where it needs to be for the next gear. The synchros still have to accelerate to match the other shaft speed.

So by changing 5-4-3-2 without ever releasing the clutch then you are still forcing the synchros to do all the work.

Personally I don't double clucth either , but when slowing for a turn I do heel-toe (braking while shifting) through all the gears, releasing the clutch for each gear, ie. 5-4-3-2 (braking steady, clutch in-blip shift-clutch out, clutch in-blip shift-clutch out, clutch in-blip shift-clutch out) With steady or increasin gbraking the entire time in a straight line before the turn.

[neal]

So by changing 5-4-3-2 without ever releasing the clutch then you are still forcing the synchros to do all the work.

No, that's what I'm saying - I don't DDC. But by going 5-4-3-2 each syncho does its share of the work. If you just went 5-2 (perhaps lingering in neutral for a while with the clutch still in as you braked) then the 2nd syncho would take a hammering.

Edited February 15, 2008 by neal

[Vulcan Grey]

No, that's what I'm saying - I don't DDC. But by going 5-4-3-2 each syncho does its share of the work. If you just went 5-2 (perhaps lingering in neutral for a while with the clutch still in as you braked) then the 2nd syncho would take a hammering.

True, you would never want to go 5-2.

So you just coast, with clutch in, and move the shifter through all the gears?

I go through all the gears but with engine braking along with foot braking, rev matching each time so I don't overrev. Going from 5-2 how do you know what revs you'll need? Seems too big a jump, especially on the track.

[kyliesmith.com]

MMMMmmm....No point in going 5-4-3-2-1 IMO if you dont have to, thats just wearing everything out more?? I admit to doing that most of the time though, but if its stopping reasonably firmly I do skip one gear and its usually third and I tend to blip into second always.

[mayevora]

MMMMmmm....No point in going 5-4-3-2-1 IMO if you dont have to, thats just wearing everything out more?? I admit to doing that most of the time though, but if its stopping reasonably firmly I do skip one gear and its usually third and I tend to blip into second always.

Yep agree kylie - I never do anything apart from block gear changes in any car I'm drriving.

[Lowtus]

The synchros still have to accelerate to match the other shaft speed.

Yup, just another part of the car doing the job it's designed to do. Like most mechanical things they will last longer with a bit of mechanical sympathy, but that's got more to do with not slamming the gear lever through the box for rushed changes than it has to do with pressing the clutch down twice. Of course, drivers who take the time to press the pedal twice probably won't be rushing their changes anyway....

[karluk29]

ok only read a few bits, but mine has done 29k and never had a clutch, and its still fine. i never do all that crazy clutch/left foot stuff, reason is im not a racing driver LOL. but as for wear, 29k on the original clutch isnt have bad me thinks, had a chip 10 for the last 15k miles aswell.

(ssshhh dont tell anyone, but i will let you into a secret, its only like a normal car with a pretty body guys)

Edited February 15, 2008 by karluk29

[M Blur]

But it is very satisfying if you get it right when braking hard for a corner on the track. No jerk as you pop the clutch and no pause before you're back on a steady throttle for the turn in. Everything should be smooth from beginning braking to going through the corner - though the ABS can sometimes throw a spanner in the works!

I'd agree tho I try to trail into most turns, which settles the car more than braking first which is a slower way and only needed for hairpins with very fast/short apexes. On track you're encouraged to heel toe, double clutch (for weaker boxes, eduro) and trail all in 1 sequence... threshold braking should be constant so the main reason to match revs is to stop any extra load which will create a lock-up.. if you're not at threshold (tough to do with ABS in the dry; but easier in the wet) then it doesn't have much value.

All shifts should be smooth, deliberate and not forced.. you'll be faster and easier on the mechs this way.. and less likely to jam the synchro or miss a gear..

I would also make only one movement but it's a very deliberate gear - neutral - gear. double clutch only if the syncrho is suffering or if the clutch is a bit soft. It becomes mroe crucial with straight cut or dog boxes of course.. where you have to be very committed to each shift, or you schoose to crash the gears and rebuild your box more often..

ABS.. what's that.. .lol

Edited February 15, 2008 by M Blur

[neal]

I agree on the trailing throttle but that's getting pretty specific on the layout of the corner and approach to it. All I was trying to emphasise was that by operating both the brake and throttle with my right foot to avoid a jerk when popping the clutch, you're by definition already on the throttle for the corner so everything is as smooth as possible.

Just so I'm clear, if I was going down a straight at say 130mph in 5th approaching a 30mph corner I'd know that I want to be in 2nd for the corner and at 30mph that's approx 3k rpm. So right foot on brake and throttle I'd begin by braking (clutch still out, no throttle), wait till the rpm drops to say 1.5k, clutch in (still braking), go through the gears 5-4-3-2 whilst at the same time on the throttle to bring the rpm back up to 3k, then clutch out at 30mph staying on the throttle and round the the corner (hopefully!)

Edited February 15, 2008 by neal

[M Blur]

That's def one way to do it Neal.. tho maybe not the fatest or smoothest way through a turn on track.. by doing all your braking before turn-in you're giving away some and the transition wont be as good so your entry speed wont be as good, you get some initial pushing or you've over-braked yourself so you'll be slow.. all relative of course and trail-braking (not trailing-throttle, which is only needed for corrections at TP or mid-turn) does mean sliding the rear in which is not everyone's cup of tea.. and easier with a ruddy big rear wing on of course..

So 130mph terminal in 5th approaching a 30mph corner 2nd gear, 30mph @ 3k rpm. I think what you said is bang on, I just tell it in a different way..

So ease right foot off throttle and squeeze the brake to full braking point.. sure

Continue max braking, feed in clutch into neutral, into 2nd, covering throttle but not applying it. When you do this is a timing issue -

Continue braking, roll the foot to blip the throttle while continuing brake (only works if your brake hits maximum stop while avoiding having to add throttle. here you can either blip and match the revs as you let out the clutch or blip the throttle a few more revs then ease out the clutch as the revs drop.. (neither way is better as you're still in a braking phase). You have to ensure you don't feed in 2 many revs as you ease the clutch out as you'll accelerate or hamper your braking or lock up; 2 little and you'll of course bog down a bit, again lengthening the transition can help with trail-braking..

Ease off the brake as you turn into the corner, this gives you time to smoothly transition your right foot back from brake to throttle pedal during the maximum corner point (jst before the apex, often at the clipping point) so you can then squeeze on max throttle.

I found Ross Bentley's book particuarly good on this..

but we digress.. :lol

[neal]

That's def one way to do it Neal.. tho maybe not the fatest or smoothest way through a turn on track.. by doing all your braking before turn-in you're giving away some and the transition wont be as good so your entry speed wont be as good, you get some initial pushing or you've over-braked yourself so you'll be slow.. all relative of course and trail-braking (not trailing-throttle, which is only needed for corrections at TP or mid-turn) does mean sliding the rear in which is not everyone's cup of tea.. and easier with a ruddy big rear wing on of course..

Haha - sorry, I meant trailing braking. Though I must say I haven't been doing it much recently - partly because my rears are shot but mainly because the second last time I was on the track was in the streaming rain, and the last time we had to start late because there was still ice on the track :laughing:

So 130mph terminal in 5th approaching a 30mph corner 2nd gear, 30mph @ 3k rpm. I think what you said is bang on, I just tell it in a different way..

So ease right foot off throttle and squeeze the brake to full braking point.. sure

Continue max braking, feed in clutch into neutral, into 2nd, covering throttle but not applying it. When you do this is a timing issue -

That the bit I don't like - if you go directly from 5-2 then the input/shaft ratio in the box it being changed 0.76>2.06 which is a hefty step and hard on the 2nd syncho. Admittedly if you wait in 5th until the road speed is low then go to 2nd the actual rpm change won't be that great. But I prefer to run through the gears 5-4-3-2 so the ratio goes up gradually 0.76>1.04>1.38>2.06 and each syncho 'shares' the change. It's not as if you have to rush that part.

Edited February 15, 2008 by neal

[t70]

If you're going from 5th to 2nd... then you should have plenty of time to rev-match and DDC for 2nd. ie -- clutch in pull out of 5th into neutral rev to 4000rpm... clutch in.. put into 2nd... re-blip to 3000rpm and engage clutch (rev difference is due to time difference while maximum braking from when you set up the gear to when you engage it.)

[M Blur]

Haha - sorry, I meant trailing braking. Though I must say I haven't been doing it much recently - partly because my rears are shot but mainly because the second last time I was on the track was in the streaming rain, and the last time we had to start late because there was still ice on the track :laughing:

That the bit I don't like - if you go directly from 5-2 then the input/shaft ratio in the box it being changed 0.76>2.06 which is a hefty step and hard on the 2nd syncho. Admittedly if you wait in 5th until the road speed is low then go to 2nd the actual rpm change won't be that great. But I prefer to run through the gears 5-4-3-2 so the ratio goes up gradually 0.76>1.04>1.38>2.06 and each syncho 'shares' the change. It's not as if you have to rush that part.

lol.. you had me worried for a mo there.. :lol

Sounds like my usual track day outing at KH.. rarely a dry line..lol

yeah I can see that now.. it would also stop you trying to bang the gear in and make you use neutral.. keeps it smooth.. main thing is you're braking all the way through. I'll give it a try but if I'm eating dunlops I'll let you know I still want to obviously make the change before the TP so don't want to lose time letteing the revs drop down too much.. just one a steady state of throttle, take a set and not too far off cam when I hit the apex

some boxes, like Porsche I hear def respond better to going down the sequence (i.e. actually .. which is what I now have + a 2-way so see how it goes.

[neal]

If you're going from 5th to 2nd... then you should have plenty of time to rev-match and DDC for 2nd. ie -- clutch in pull out of 5th into neutral rev to 4000rpm... clutch in.. put into 2nd... re-blip to 3000rpm and engage clutch (rev difference is due to time difference while maximum braking from when you set up the gear to when you engage it.)

Hehe - yep you're absolutely right. But I'd prefer to use a consistent approach and 5-2 is unusual, most of the time you're only dropping one maybe two gears and DDCing that is a bit hectic. Only exception to running through the gears would be if I'm pulling up at say a set of lights in which case I just leave it in the original gear until stationary then shift to neutral. That way the input shaft is stationary for engaging 1st.

Edited February 15, 2008 by neal

[t70]

Clever plan Neal! I must admit that I don't always double clutch on maximum braking -- One would have to skip a gear each time to warrant the time necessary. I do double clutch for most down-shifting situations though... and it's really only because it's fun and it keeps my skill level up. I very rarely double clutch on the upshift... however, I would probably consider it on the V8 when shifting from first to second because of the weak synchros in second... Though, I can't imagine another car that i've driven where that is truly necessary -- unless the synchros are mashed.

[neal]

Well that's the thing. Since I don't DDC the next best thing to avoid a weak point and save the box is to share out the work over all the synchos, hence the running through the gears even if I don't pop the clutch on each gear. And always stop in gear so the primary shaft is stationary for engaging first (or reverse).

As regards the 1-2 upshift, I would always short shift (4k max) that anyway. Apart from pulling away or if you're stuck in traffic, 1st is pretty pointless on the V8. It's too short and just lights up the rears, better just to get into 2nd as soon as possible. There's more than enough torque to pull easily in 2nd from practically any rpm.

Edited February 16, 2008 by neal

[jeff_hooper]

This is all such soft stuff. Back in 1977 my mate had an old Morris Marina with a totally shagged gearbox - you had to double de-clutch UP and DOWN and get yours revs and timing absolutely right...

Another fun trick I used to do was in an MG Metro I had for over 20 years and 100,000 miles and at the end was actually trying to break it, over the last few years, severak times I drove it without using the clutch at all other than when setting of from stationery... A fun challenge.

Last year a mate had his clutch cable snap on a Renault saloon and he was looking for a tow a few miles to the garage, but when he started flapping about never having been towed before. I suggested it might be easier for him to drive it.. He thought I was mad so I drove him around the estate a few times and showed him how to change gear without the clutch and how to pull away in first on the starter motor... it was all flat roads with no hill starts...

He chose to do it that way rather than be towed and made it no problem...

Jeff H

[oneshot]

Yep

When I was at university I had an Austin Healey Sprite (not a frogeye!!) and the clutch failed on the Friday. Couldn't get to a garage until Monday so I drove it around without the clutch for the weekend. Ok until you come to traffic lights etc