I hope this isn't too OT, but I often have trouble changing UP the gears in the Furby - when really giving it the beans if I try and shift too quick it just misses and refuses to change (or makes lovely crunching noises) and I've noticed that the engine doesn't lose revs as quickly as a petrol when you drop the clutch and take your foot off the gas. It has meant a change in technique like accelerate/clutchandlift/wait one thousand/into gear/boot down etc...

As for the double de-clutching thing, I always find it enough to drop the clutch and blip the throttle (without raising the clutch in neutral) for a smooth downchange. Actually when I really need the brakes I use the extra engine braking from NOT blipping and slipping the clutch to bring the gear in. I REALLY need some TT brakes

some people are getting confused and thinking that DDCing is used up the box...

I know some excellent drivers who use it up and down the box..... I personally think they're just showing off though

Chris

I hope this isn't too OT, but I often have trouble changing UP the gears in the Furby - when really giving it the beans if I try and shift too quick it just misses and refuses to change (or makes lovely crunching noises) and I've noticed that the engine doesn't lose revs as quickly as a petrol when you drop the clutch and take your foot off the gas. It has meant a change in technique like accelerate/clutchandlift/wait one thousand/into gear/boot down etc...

Can't remember if it's the same on the Fabia, but on my diesel the revs seem to fall nice and gradually at the top end (4-4.5k) which makes smooth changes nice and easy, but changing lower down the rev range, eg at 2.5k, the revs plummet and require staying on the gas to sustain them. I suspect it's summat to do with the momentum in the DMF, but could be wrong.

Chris

And conversely, I find that the neutral, off throttle drop off rate is just about right for me.

I see a dead thread here, let me expand double de-clutching further.

If you are well able to master this then there is a big advantage, let me explain, The idea off double declu... as we know matches the engine revs. to the speed the clutch plate is turning. So if your clutch without warning becomes inoperable, what do you do? How do you drive home? Easy, you use the doble de-declutch method to change gear, up and down the box, problem solved. I've always practised this since I was a teenager each time I changed cars just to get used to the revs I can change gear at and it works ( Dad taught me the method of course). I've only had one cluch go all these years and managed to drive home, a bit hairy as you can imagine.

2 flaws in my idea I hear you say.

1. If the clutch breaks and the plates are stuck open then it's impossible to go any where, well true you are not going anywhere if this happens.

2. What happens if you have to stop? this can be solved by just braking the car till you stop and will stall the engine, you have already changed down the box to 1st. so when you want to move off again restart the engine and off you go again albeit a bit of a judder and not doing the flywheel much good so it's best not to practise this bit. The battery needs to be in tip top condition to do this..

So as the original poster says double declutching is useful.

I had to do that in my old Range Rover once.

Glad I knew how to do that, the army taught me in big trucks.

I do block shift for big downward changes in speed with a throttle blip.

It works for me...

Agree entirely with the above. I sometimes do this to smooth changes when down changing at speed but it takes practice with a Diesel engine as the revs take a bit longer to build. Heel and toe is a fine art which sometimes I can manage and sometimes can't. Some cars nowadays have pedal spacing where it is impossible. I could manage it on my Uno and in the Skoda but it was impossible in my Pug 106 as the throttle pedal was a tiny short travel thing set some way apart and lower than the brake. At motorshow I always look at the pedal spacing: The MINI has great pedal layout. The Elise (unsurprisingly) is terrific with the throttle right next to the brake. The worst, really surprisingly was Morgan. The accelerator was miles from the brake and you would have to have feet the size of the BFG to heel and toe.

Edited 30 May, 200917 yr by Matt Bodycombe

I am glad there are some drivers out there who can get themselves out of trouble when needed. Tried the double de-clutch up on the Fabia ok but it is lot more difficult downchanging as you say trying to get the revs up.

Soot just read your post again and am a bit confused, if your clutch fails, how are you supposed to double de- clutch. Are you talking about the art of precisely matching engine revs to enable clean up and down changes WITHOUT using the clutch. This is something i have never had the cajones to try.

I think what he is saying is that if you can double declutch shift then it will be easier to pull off a clutchless shift in an emergency.

Probably, that's what I thought he meant anyway.

Soot just read your post again and am a bit confused, if your clutch fails, how are you supposed to double de- clutch. Are you talking about the art of precisely matching engine revs to enable clean up and down changes WITHOUT using the clutch. This is something i have never had the cajones to try.

This didn't make much sense to me either - no clutch means no double d. I once drove a Vauxhall VX2.3 estate for a week with no clutch, bit of a pain but quite possible, but I would have to say I didn't care what happened to the piece of junk. No where near as hairy as a auto Cortina 2.3 with no brakes:D

I often do this when changing down at higher speeds to smooth it out. I was tought this technique by my driving instructor and also further mastered the art while driving a 1960 something bus that required you to do it to change gear!

I have also change down and up gear without using the clutch a few times in my car using this technique so would no doubt be able to manage in a clutch breakage scenario!

Basically you don't touch the clutch and use the same method by reving the engine but it takes a bit more precision with the revs and just 'feeling' on the gear sitck until it slides into gear. It's basically doing the same as DDC but without using the lutch and you have to make sure the revs are spot on so that the clutch and gears are spinning as fast as the wheels on the car.

Phil

I think what he is saying is that if you can double declutch shift then it will be easier to pull off a clutchless shift in an emergency.

That's how I read it too and the process means that you're already doing the rev-match when the car is crossing neutral, rather than when the clutch pedal is down, so if you don't have the option of using a clutch you shouldn't notice.

I wish I'd been familiar technique when the clutch pedal in the Fabia snapped as I could have braved more than 1st gear when I limped it to a safe place for the recovery truck

Chris

Soot just read your post again and am a bit confused, if your clutch fails, how are you supposed to double de- clutch. Are you talking about the art of precisely matching engine revs to enable clean up and down changes WITHOUT using the clutch. This is something i have never had the cajones to try.

Sorry got a bit off subject, I am referring to the revs bit when the gear lever is in neutral. Its is kinda double do dah without using the clutch.

You can double do dah by forcing the gear lever into neutral, give it revs then drop into the lower gear, changing up, knock the lever into neutral,momentarrily , don't rev and it should slip easily into the gear up if the revs match the cars speed, The trick is knowing exactly what speed to change up. Downshifting just give the throttle a real good rev and keep pressure on the lever when the revs and speed off the car match the lever will drop into gear all by itself.

Practising this too much is obviously not a good idea. But if you drive very steadily like yer granny then this does work.

An excellent explanation of what it is and how it's achieved at TCS Racing - Racing Tips - Double Declutching

Chris

Chris - link doesn't come up with anything useful any more. care to amend?

In most modern syncro boxes all you need to do is blip the throttle when the clutch is down. You only need to use it when getting into gear early ie flat out then hard braking into a corner, you want to get down the box, so you can sort the corner out and get on the power early. It does help a peaky engine keep on cam. In a crash box you need to bring the clutch up while bliping to match the speeds better. In a dog box you can bang it in without the clutch, but you still have to blip. Get the flying Finns video! You can just take the syncros out of a std box and use it as a dog box, but it will not take as much hammer as a dog box. This is a trick (cheat) done on grp N cars, means you can leftfoot brake and do clutchless down changes.

I can heartily recommend NOT practising clutchless gearchanges in your daily driver as part of a "flat out then hard braking into a corner" scenario, unless you've got a supply of spare gearboxes handy. They're not really built for that kind of treatment.

And whats the difference between blipping the throttle with clutch in and double de-clutching? I do blip if I'm changing down in say the snow or wet or to make it smoother, don't see the point in DDC

And whats the difference between blipping the throttle with clutch in and double de-clutching? I do blip if I'm changing down in say the snow or wet or to make it smoother, don't see the point in DDC

Blipping the throttle with the clutch in while you are doing the gear change, or before or after the gear change, will match the engine speed to the road speed so that when you bring the clutch up, the car does not feel engine braking.

DDC on the other hand is done between gears: Clutch down, neutral, clutch up and blip, clutch down and into the lower gear.

DDC is used to match the gear shaft speeds so that you can get the car into say first at highish speeds / revs. I find it particulalry useful on a cold gearbox full of full synthetic oil. The oil tends to a bit too slippery for the synchromesh to work when the gearbox is cold so using DDC to get into first while still on the move approaching a slow exit from a junction is ideal.

Chris

Chris sums it up nicely

This video demo's the steps......

Chris

Can't say if it is true now but in the early 1980's the Lancashire Constabulary Motor Driving School still taught double declutching and insisted drivers under instruction used it at all times.

It was obviously a necessary skill at the time where some older cars we would encounter would have crash boxes on some or all of the gears - particularly land rovers.

Even then there was debate about wether it was necessary and indeed if it damaged newer gear boxes.

We were required to double decluch both going up and down the gears.

All the gears had to be used going up the gears, ie, 1 2 3 4 but it was permissable to skip gear on the way down, eg 4 to 1 or even 4 to neutral when stopping.

Instructors were particularly disaproving of droping a gear and using the engine to slow ther car - always use the brakes and only then pick the right gear using ddc to match the correct revs.

It took me years to stop using double declutching although I still think it is a smoother down shift.

I coudn't say whether it slows a car down but remember advanced police drivers being taught to drive at 120 mph plus for traffic duties were not disadvantaged by ddc.

That is not to say that has anything to do with racing or even true for ordinary driving. All I'm saying is speed was being balanced with style, car sympathy and smoothness..

The one benefit of acquiring the habit is that it will help with clutchless shifts since the only way to do them is to time the revs exactly. The issue is not changing up since they fly in but going down the box where engine revs will have to rise to shift to a lower gear at the same road speed. Compound that with braking and changing gears and it becomes very difficult to down shift without a clutch. Once you come off the revs, and in particular once you apply brakes, it is very difficult to get the car out of gear. The answer is to knock it out of gear whilst the revs are constant or just rising slightly (blip throtle), then brake, then match revs and select the lower gear with a firm throw of the gear leaver.

Do it wrong and you will grind metal. Therefore, NOT recomended on a gear box you own your self.

However, clutchless shifting was useful when a clutch cable snaps on a Ford Granada (or any Ford) which happened often on high mileage examples in the '80s. The trick is to knock it out of gear when stopping at lights, switch off engine, select ist and start the car in gear with handbrake off when the lights change.

Nice to have a professional's point of view on these threads, FriendlyFire

There's a big difference between DDC and 'rev-matching' I now see. What are the benefits of DDC over just rev-matching (on a modern 'box)?

I always try and rev-match as I think I'm adding a certain 'finesse' to my driving, but is it purely superficial?

I always try and rev-match as I think I'm adding a certain 'finesse' to my driving, but is it purely superficial?

Rev matching is mechanically sympathetic as you're aligning the input and output shafts before engaging the gear so the syncros have to do less work and your passengers get a nice smooth ride.

DDC is really a technique that sits on top of that and defines how you rev match. With the normal change, clutch goes in, revs get matched, clutch comes out. With DDC, clutch goes in, change to neutral, clutch come out, rev match, clutch goes in, into target gear, clutch comes out. On a modern gear box there isn't any real advantage to doing it, although a side effect is that it slows your changes down to a point which means you're having to squeeze and holding the right revs, rather than the blip-and-catch approach, so it can sharpen accuracy and control.

Chris

Yeah, 'blip and catch' nicely describes my heel and toe efforts using the G25 on the PC. In rFactor I'm a driving god

In a real car, where the pedals are half a mile apart, it's* hopeless.

*I'm