Double de clutching / Sliding
Discussion
After I bought my S, someone suggested mastering the art of double de clutching. Never tried until today, downshifting from 3rd to 2nd, tricky to get it just right but good fun 
Anyone always double de clutch habitually, or for fun? I remember paul from Austec doing it masterfully right before taking roundabouts (sounded great!) and then sliding the back end out slightly on exit
Speaking of putting the back out, is this hard to master? How responsive or easy is it to tell when an S is about to go, and maintain direction/control my apportioning throttle/steering during the slide. Im not about to try it
much safer asking more experienced S owners from the comfort of my easychair, with hotwater bottle, slippers and blanket 
Anyone always double de clutch habitually, or for fun? I remember paul from Austec doing it masterfully right before taking roundabouts (sounded great!) and then sliding the back end out slightly on exit
Speaking of putting the back out, is this hard to master? How responsive or easy is it to tell when an S is about to go, and maintain direction/control my apportioning throttle/steering during the slide. Im not about to try it
much safer asking more experienced S owners from the comfort of my easychair, with hotwater bottle, slippers and blanket I usually double declutch on downchanges, it's better for the gearbox and the clutch, and also sounds good in an S!
As for getting used to getting the tail out, well a lot depends on your car's suspension setup, the type of tyres and the amount of wear etc... no two cars will be identical. It needs a lot of practice!
You should get used to the principles on a skid pan session or something - they'll teach you skid control and also braking techniques. Skills for life Bob - and the life may be yours one day.
As for getting used to getting the tail out, well a lot depends on your car's suspension setup, the type of tyres and the amount of wear etc... no two cars will be identical. It needs a lot of practice!
You should get used to the principles on a skid pan session or something - they'll teach you skid control and also braking techniques. Skills for life Bob - and the life may be yours one day.
Double de-clutching is a waste of time unless you have a knackered gearbox. But, matching revs on downshifts is an essential skill if you want to make progress safely. One way (but not the only way) to do this is the 'heel and toe' technique where you blip the throttle to match the engine revs while maintaining pressure on the brakes. It takes a little practice to get the knack but quickly becomes second nature.
GreenV8S said:
Double de-clutching is a waste of time unless you have a knackered gearbox. But, matching revs on downshifts is an essential skill if you want to make progress safely. One way (but not the only way) to do this is the 'heel and toe' technique where you blip the throttle to match the engine revs while maintaining pressure on the brakes. It takes a little practice to get the knack but quickly becomes second nature.
Peter, I know you've a lot of experience of TVRs and of racing etc - but I always believed that for road driving, double declutching is kinder to the box and the clutch. I agree the other way is faster, but unless you're racing, that's not really the point...
each to their own though, it's not worth falling out over!
GreenV8S said:
It takes a little practice to get the knack but quickly becomes second nature.
Heel and toe as in the same foot, heel on brake toe on accelerator, ballerina shoes on?
Its easy enough to feel precisely how well a double de clutch was executed, Im sure with more practise it'll be second nature as you say, although the heel and toe might take a while longer to master!
tvrgit said:I think what Peter is trying to say, is that you don't need to hit the clutch twice, so the action is like double de-clutching, just leave your left foot down. This means braking either side of the down change, but is considerably easier, and sounds good too! Consider this technique the same as changing down on a motorbike.
Double de-clutching is a waste of time unless you have a knackered gearbox. But, matching revs on downshifts is an essential skill if you want to make progress safely. One way (but not the only way) to do this is the 'heel and toe' technique where you blip the throttle to match the engine revs while maintaining pressure on the brakes. It takes a little practice to get the knack but quickly becomes second nature.
Peter, I know you've a lot of experience of TVRs and of racing etc - but I always believed that for road driving, double declutching is kinder to the box and the clutch. I agree the other way is faster, but unless you're racing, that's not really the point...
each to their own though, it's not worth falling out over!
HTH
bridgdav said:
First left foot braking experiences....
Tooth removal from the steering wheel...
Passenger 'What did you do that for..?'
Like forgetting you are driving an Auto, then proceeding to engage the clutch.
How many of us can honestly say we haven't done this...?
My diesel passat TDi is an auto and it's also chipped and this makes a fast combination for pullimg away but I find it much quicker if I hold the car on the brakes with my clutch foot whilst my right foot is ready for business on the throttle.
The response from passengers has been one of surprise at how quick an oil burner can be.
You can only heel-toe in specific shoes in my S, as the accel is too far below the brake. I will have to remember to sort this out over Christmas.
Bob be careful with this technique unless you can try it where you can not do any harm. The V8S has a lot of torque and a light backend under braking. Too many / few revs at the wrong moment could leave you in a spin, especially in the wet.
The V8 is actually quite easy to get the hang of because the flywheel effect stops the revs changing too fast.
It is much easier to do when you are just driving about, but much of my technique goes out the window when I am actually trying to go fast. (Probably true of any adrenalin inducing activity)
Z
Bob be careful with this technique unless you can try it where you can not do any harm. The V8S has a lot of torque and a light backend under braking. Too many / few revs at the wrong moment could leave you in a spin, especially in the wet.
The V8 is actually quite easy to get the hang of because the flywheel effect stops the revs changing too fast.
It is much easier to do when you are just driving about, but much of my technique goes out the window when I am actually trying to go fast. (Probably true of any adrenalin inducing activity)
Z
tvrgit said:
Peter, I know you've a lot of experience of TVRs and of racing etc - but I always believed that for road driving, double declutching is kinder to the box and the clutch. I agree the other way is faster, but unless you're racing, that's not really the point...
each to their own though, it's not worth falling out over!
Sometimes it is useful to double de-clutch. When there's a big change in revs and the gearbox is hot the synchros take longer to bring the 'box up to speed and you can sometimes match the engine revs quicker than the synchros will bring the gearbox up to speed. In this situation it is actually quicker to double declutch. I also agree that if you're in a hurry it is kinder on the transmission to double declutch than risk beating the synchros and grinding metal. Double-declutching definitely has its uses. But I still maintain that it is not a technique that is necessary under normal conditions. The problem I have with it is that it needs care to get it right, extends the time taken to change gear and keeps your gear lever hand busy, keeps your feet busy longer and diverts attention, at a very critical time when the driver should really be concentrating on braking, steering, and lines.
As well as the distraction to the driver on the road, it is also a distraction during discussions of driving technique. Time and again I come across people who are confused about the difference between heel and toe versus double declutching and don't know what they are for. This is why I make no apology for saying this each time the topic crops up: double declutching is largely irrelevent, concentrate on getting the heel and toe technique sorted out or find some other way to match revs. Getting the revs wrong on a downshift is horribly dangerous and I reckon probably accounts for at least half the single vehicle TVR accidents.
I'm happy enough with that - I think the main point, as you say, is matching engine revs and wheel speeds - TVR's are not the sort of cars where you want a lot of sudden engine braking at the wrong end!
It's funny how techniques develop - I learned to double declutch because a lot of the scrappers I drove in my early years did have knackered gearboxes, so I can do it almost without thinking, and without a huge delay.
Despite a starship mileage since then, I've never really got heel and toe to the same degree, I still have to think about it so it actually takes me longer!
It's funny how techniques develop - I learned to double declutch because a lot of the scrappers I drove in my early years did have knackered gearboxes, so I can do it almost without thinking, and without a huge delay.
Despite a starship mileage since then, I've never really got heel and toe to the same degree, I still have to think about it so it actually takes me longer!
GreenV8S said:
Getting the revs wrong on a downshift is horribly dangerous and I reckon probably accounts for at least half the single vehicle TVR accidents.
I'll remember that. I've learnt so much since I started driving, the more I learn the more I realise how much I dont know/how much more there is to learn. The same with all things, I suppose.
If you're figures are even close to accurate, they're scary!
I'll admit I still dont fully understand heel and toe yet, but will keep practising the double de lurching and try not to double de crunch
50%
I know we discussed this here before, but why exactly do the rear wheels 'lock up' as opposed to loosing traction momentarily? (If I recall correctly, someone warned of this during downshifts)ukbob said:
If you're figures are even close to accurate, they're scary!
I don't have any facts to back this up, it's just the impression I've got from seeing offs and near misses over the last few years. Losing the back end under braking seems to be the most common way to go off, and I think this is caused by a combination of too much rear brake bias, insufficient rebound damping at the rear, and failure to match revs. Its quite scary being in a car with somebody who doesn't do it, you can feel the car squirming more and more the harder they push into the corners.
ukbob said:
I'll admit I still dont fully understand heel and toe yet, but will keep practising the double de lurching and try not to double de crunch
ukbob said:
50%
You're right that it isn't as simple as the wheels actually locking up. It is more of a balancing act between the engine braking trying to slow the rear wheels down to engine speed, the rear brakes trying to stop them, and friction between the tyres and the road trying to keep them going at road speed. What usually seems to happen is the sudden engine braking slows the wheels down to engine speed but the wheels don't actually stop. For example the wheels might slow down from say 80 mph to 60 mph while the car keeps going at 80 mph. When this happens the back end of the car loses all lateral grip and the car becomes unstable. Then it is just a question of whether the driver can keep the car balanced until they grip again, or whether the car will swap ends. Since this mistake is common with inexperienced drivers, they're often not well placed to keep it under control and it is a down to luck whether the car spins before they finish braking.
GreenV8S said:I suppose this is quite possible at any speed, depending on the severity of the clutchout or the degree/mistime of the 'manouver'?
What usually seems to happen is the sudden engine braking slows the wheels down to engine speed but the wheels don't actually stop. For example the wheels might slow down from say 80 mph to 60 mph while the car keeps going at 80 mph. When this happens the back end of the car loses all lateral grip and the car becomes unstable.
I only tried it at -40mph. Another hypothetical question - those that double de clutch and have accidents, Im assuming we are talking about a fairly rapid or overconfident executions though, right? Im playing as gently as I can without being too slow, at lowish speeds only on straights.
ukbob said:
I only tried it at -40mph. Another hypothetical question - those that double de clutch and have accidents, Im assuming we are talking about a fairly rapid or overconfident executions though, right? Im playing as gently as I can without being too slow, at lowish speeds only on straights.
Sorry if I implied that double-declutching caused accidents. The problem is failure to match engine revs before engaging the clutch. The more abruptly the clutch is engaged the worse the effect is. Even if you are confident about matching the revs accurately it is worth engaging the clutch gently because this greatly reduces the effect of any mismatch. And if in doubt, it is better to engage the clutch with too much revs rather than too little.
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