TD in DC

I have been practicing double-clutch heel/toeing ("DCHT") in preparation for Skippy, which requires students in the racing school to use DCHTing. (I actually try to practice all of the track techniques on the street so that I can try to commit things to habit).

Until this point, I had always single clutched:

(a) Brake using the left portion of the ball of my right foot;
(b) depress clutch near end of braking zone;
(c) shift into neutral;
(d) blip throttle with entire right side of right foot;
(e) shift into appropriate gear (I usually skip gears on the track); and
(f) release clutch.

At this point, I have this technique pretty well down and I can do it smoothly and quickly without chirping tires or overreving motor. I no longer have to think about it. I can't remember the instructor who taught me to pause briefly in neutral when shifting, but that tip was gold, and I am very thankful.

In order to DCHT, I now:

(a) Brake using the left portion of the ball of my right foot;
(b) depress clutch near end of braking zone;
(c) shift into neutral;
(d) release clutch;
(e) blip throttle with entire right side of right foot;
(f) depress clutch
(g) shift into appropriate gear; and
(h) release clutch.

The extra steps are not really a problem. However, what is very different is that it takes a much larger blip of the throttle to rev match.

Since you are blipping with the clutch engaged (not pushing the pedal), the engine doesn't want to rev as easily, and it slows down much more quickly. As a result, your margin of error for getting the second part of the process done (i.e., f through h) is much narrower.

You must roll your foot to the right with much more force and decisiveness in order to get a decent blip. Then, you must push clutch, shift, and release very quickly or the revs will have fallen too much and you significantly increase the chance of chirping your tires. This little exercise makes me appreciate KingLeh's shifting even more

It makes you much more aware of rev matching, speed of the car at the end of the braking zone, and release point of the clutch. As such, even though most of us do not "need" to DCHT, you might want to try to learn how to do it so that you improve your overall shifting technique, even if you do not end up using it on the track.

It sorta reminds me of my experience with braking and ABS. In the 996, I never had an issue with braking and never engaged the ABS. I honestly couldn't understand the emphasis on "threshold braking." Then, when I moved to the 944 without ABS, I learned how much control you really have over braking forces and the importance of proper threshold braking. Now I am better at braking in the 996 as well.

It is like taking a microscope to a specific technique and realizing that the only reason you didn't know how much you could improve was that you just weren't looking hard enough.

For all you fellow newbies, try to double-clutch heal/toe, you might like it.

InThePocket

Thanks for the description TD. I've only tried, and gotten fairly comfortable with the single-cluctch technique. I need to practice this. I remember reading that Danny Sullivan never double-clutched. He claimed IIRC that a more exagerated single-clutch blip would accompish the same thing.?

Roger

steve775

You can read about what you learned in a very good book, ISBN # 0-8376-0226-2, it says, "The blip is much more effective, however, if you positively connect the engine and input shaft by letting the clutch back out in neutral."

Also don't be slow to move into the next [lower] gear, it has to be done right away.

Benton

I did the Bertil Roos school, and the straight-cut gears are awesome to work with. It's really not that hard to do quickly once you get the hang of it. I'd love to stick a dog box into my 928, but a brand new transaxle is pretty expensive! Make sure you read Sunday Driver's post where he links to an article by Hewland about how to shift dog boxes.

38D

While this is an interesting excercies, it's not going to be of much use in your 944 or 996.

Jaws911

"While this is an interesting excercies, it's not going to be of much use in your 944 or 996."

Why not? (asks ownerof '86 911, who practices , but is VERY far from adept at "DCHT")

38D

Because all Porsches have a synchomesh gearbox, so no need to double clutch. The wear on the synchros when doing the single clutch method properly is very minimal (that's what they are designed to do), and it is much faster.

TD in DC

Agreed 100%. My point is that learning to do this might help you improve your single-clutch shifting by requiring you to be more precise. If you learn how to be more precise by using a more complex shifting technique, you should be even better when you go back to single-clutch shifting.

What can I say. It is wintertime, my wife and kids are away, and I am bored.

FixedWing

I disagree. Double-clutching will allow for much faster downshifts -- especially when skipping gears. Syncros take time.

Stephen

38D

I would bet that nearly all pro racers (with synchromesh gearboxes) still use the single clutch/cycle thru all the gears technique.

Geo

Good God.

Do the cars have wire wheels and drum brakes too? Talk about stuck in the 60s. Peace, love, dope......

Seriously, double clutching is ancient history. Interesting to know, but not all that useful. When I went to the Spenard-David Racing School in 89 I had to unlearn double clutching. I originally single clutched, but thanks to a description in R&T on how to heel/toe by Dennis Simmanitis (sp?), someone who I used to admire, he included double clutching in heel/toe so I taught myself to do it. When I found out it was an anachronism, it took me a while to get used to not doing it again.

Back when pro racers actually shifted their own gears in an H pattern, pros had already stopped double clutching as worthless. Watch "Drive to Win" with Mario Andretti and Gilbert Pednault and you will hear a number of pro drivers tell you it's not necessary.

For those suggesting it's necessary with straight-cut gears, you've actually got it backwards. With straight-cut gears you don't even need the clutch. Just blip between gears. I did it a number of times very smoothly in the Reynard 86SF F2000 cars I drove at school.

Again, interesting to know, but pretty useless beyond that. Unless of course you drive a car with a fold-down windscreen, a bonnet held down with leather straps with buckles, and wire wheels.

Geo

Quite correct.

JerryW

Just got back from Skippy in Laguna last week. They teach about the double clutch technique but you use the single clutch in the school cars. The reason they teach the double technique if if you end up driving an older racer that still requires it.
Just give it a large blip !

FixedWing

I think that is probably true.

Stephen

FixedWing

Let me guess ... were you using a Hewland gearbox at Spenard-David? That would be a pretty good reason to un-learn double-clutching.

I am aware that a lot of top drivers don't double-clutch but I'm not convinced that necessarily makes it a useless technique.

Stephen