Double Clutching Article

[taz_rocks_miami]

Here are some links to vids on double clutching and heal and toe downshifting guys:

http://video.google.com/videoplay?do...88575741675515

http://video.google.com/videoplay?do...73124257173554

http://video.google.com/videoplay?do...54456325722769

Article on the different shifting tecniques:

http://www.waycoolinc.com/z3/essenti...e/shifting.htm

[NSXType-R]

Thanks Taz, those were some pretty helpful videos!

[magracer]

heel toe is a technique which provides maximum decelleration in anticipation of accelerating out at the end

I don't agree with your statement. Heel and toe allows you to syncronise your engine speed and gearbox speed. It has nothing to do with maximum deceleration. That is achieved with your brakes, not your gearbox and not your engine (we are talking cars and normal road conditions here). Ultimately it allows you to be at the optimal gear change when you need it. It also makes downshifting smoother so the balance of the car is not disturbed when you engage a gear and thus can brake or corner at the limit.

We agree, in that they are similar techniques for different purposes, but my message for the one that started the thread is that double clutching for a normal road car is nearly useless, while toe and heeling besides being useful is fun.

[h00t_h00t]

If you find heel and toe useful on the roads you need to slow down a bit

[NSXType-R]

I don't agree with your statement. Heel and toe allows you to syncronise your engine speed and gearbox speed. It has nothing to do with maximum deceleration. That is achieved with your brakes, not your gearbox and not your engine (we are talking cars and normal road conditions here). Ultimately it allows you to be at the optimal gear change when you need it. It also makes downshifting smoother so the balance of the car is not disturbed when you engage a gear and thus can brake or corner at the limit.

Heel and toe by itself doesn't decelerate your car but by using it it can help you engine brake faster which would indirectly lead to deceleration, correct?

[m5child]

it is if you do it bad, the theory behind downshifting to slow down is to use the friction of the engine's internal parts instead of the brakes

i have to repeat ... the ENGINE'S internal parts, not the transmission's

the friction of the engine's parts are always the same (or differ by negligible amounts) but the gear ratios have a multiplying effect, this is why slowing down in 5th by coasting isnt as good as slowing down in 4th while coasting

anyways back to double clutching, the whole point of this technique is to rev match both the engine adn transmission gears prior to the actual downshift, granny shifting means you only rev match the engine, but the internal gears are all moving at the wrong speed, when you shift like this, the syncros must take up the slack and wear down as a result, modern sycro's are really good and will last much longer then other parts of the car thus making double clutching unneccesary in most situations, but most people still want to know what it is, and want to learn the technique

Okay, Now i have a much better idea on how this works... thanks guys... but one last question... how do you manage to get the tranny and the engine to match revs? i mean, its kinda easy for the engine since you have a tachometer on your dash which shows revolutions but since i haven't seen a car that has an RPM meter on the tranny, it would be hard to figure out how much you should rev the engine, no? (since the engine is the only component who's RPM's we can manipulate via the gas pedal)

[magracer]

Okay, Now i have a much better idea on how this works... thanks guys... but one last question... how do you manage to get the tranny and the engine to match revs? i mean, its kinda easy for the engine since you have a tachometer on your dash which shows revolutions but since i haven't seen a car that has an RPM meter on the tranny, it would be hard to figure out how much you should rev the engine, no? (since the engine is the only component who's RPM's we can manipulate via the gas pedal)

Only experience can help you there. I guess its mix of sound, vibration and pedal position. At first it will not be too smooth, but soon it will become second nature. If you are doing it well it almost feels as if you don't need the clutch... warning: you DO!!!. I messed a gearbox syncro because I thought I was better than I really was.

[taz_rocks_miami]

Thanks Taz, those were some pretty helpful videos!

You're welcome

Heel and toe by itself doesn't decelerate your car but by using it it can help you engine brake faster which would indirectly lead to deceleration, correct?

Engine braking takes some of the strain off the brakes as you're slowing down, but it's not a substitute for actually braking. Specially at track speeds. Heal and toeing will help you downshift smoothly to the correct gear as you exit a corner.

[KnifeEdge_2K1]

I don't agree with your statement. Heel and toe allows you to syncronise your engine speed and gearbox speed. It has nothing to do with maximum deceleration. That is achieved with your brakes, not your gearbox and not your engine (we are talking cars and normal road conditions here). Ultimately it allows you to be at the optimal gear change when you need it. It also makes downshifting smoother so the balance of the car is not disturbed when you engage a gear and thus can brake or corner at the limit.

We agree, in that they are similar techniques for different purposes, but my message for the one that started the thread is that double clutching for a normal road car is nearly useless, while toe and heeling besides being useful is fun.

the act of blipping the throttle allows you get the engine to be at the correct rpms for the lower gear, but that's not all heel and toe accomplishes

heel toe allows you to brake AND rev match at the same time, if you had to do these 2 motions seperately you would need to brake much earlier to allow yourself the time to shift into the lower gear

[KnifeEdge_2K1]

Okay, Now i have a much better idea on how this works... thanks guys... but one last question... how do you manage to get the tranny and the engine to match revs? i mean, its kinda easy for the engine since you have a tachometer on your dash which shows revolutions but since i haven't seen a car that has an RPM meter on the tranny, it would be hard to figure out how much you should rev the engine, no? (since the engine is the only component who's RPM's we can manipulate via the gas pedal)

that's what double clutching is for, when you're in neutral with the clutch let out (not depressed) the input side gears of the tranny and the engine are running in sync, when you match the engine's rpm you are matching the transmission rpms at the same time

for more detail you really need to know the internal mechanics of a manual transmission, there's a good article in howstuffworks.com that can explain this alot better then i can

[magracer]

the act of blipping the throttle allows you get the engine to be at the correct rpms for the lower gear, but that's not all heel and toe accomplishes

heel toe allows you to brake AND rev match at the same time, if you had to do these 2 motions seperately you would need to brake much earlier to allow yourself the time to shift into the lower gear

But left foot braking is cooler...

[h00t_h00t]

Only if you don't have a clutch.

[KnifeEdge_2K1]

But left foot braking is cooler...

that doesnt let you shift down tho

and the point of left foot braking is to increase rearward brake bias to induce oversteer. nothing to do with shifting down or slowing down

[magracer]

that doesnt let you shift down tho

and the point of left foot braking is to increase rearward brake bias to induce oversteer. nothing to do with shifting down or slowing down

Just as blipping has nothing to do with toe and heel...

While we are all changing subjects, let's discuss chess now.

p.s. There's a famous myth that says that when a rookie in a series is too fast, you just have to mention left foot braking for him to get slower for a couple races. That's why I mentioned left foot braking. And left foot braking is most fun when you DO have a clutch... a little bit of samba dancing goes on at the pedals.

[cmcpokey]

If you find heel and toe useful on the roads you need to slow down a bit

i completely disagree.. i heel toe at all rpms in all conditions. it just makes for a smoother drive. and it does help slow down a lot from speed. you just have to be quick with your shifting and blipping.