I never double clutch, didnt know what it was...but I always heel toe...but now I will 2x clutch as well..thanks for the information!

 

I think at TAJ I am going to lean how to properly "Heel Toe"

 

I H&T at every opportunity

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by 944GASM:
<strong>I never double clutch, didnt know what it was...but I always heel toe...but now I will 2x clutch as well..</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Don't be silly. No need to double clutch. You wouldn't be taught that at racing school and racers don't double clutch.

 

I don't know if this has changed since 1997 when I went, but I was taught double-clutching at Skip Barber's Racing School. Of course, once you learned it and got good at it they mentioned that since those boxes in the Formula Dodges don't have synchros, you don't really need the clutch except to leave the line anyway if you're really good with rev matching....same as my old math teachers in school...always wanted to teach you the hard way first. BTW, no clutch is NOT good for your street car with synchros from what I've been taught to understand.

The reason for it is to match the input shaft speed to the revs on the engine when the car is in neutral as the clutch must be let out to spin it up.

Heel and toeing works best for me in any vehicle when I'm braking deep....slower and it's more work to get the foot over on the gas. Takes practice.

I do rev match when downshifting before corners as it helps keep the car balanced best.

 

I dunno, I just feel like I'm getting much smoother downshifts w/ double clutching than just plain rev matching, and I can't see how it'd damage the clutch / gearbox either. Anybody care to enlighten me?

 

I was taught to double clutch at skip barber as well. As of 2000 they still used straight cut, non-syncro boxes in their formula dodges. I think I double clutch because it is so satisfying when I get it right

 

I'm really surprised Skippy teaches double clutching. It's really old old school. I know the Jim Russell school has not for some time and the Spenard-David school did not when I went there. In fact, when I went to Spenard I was double clutching and stopped that very weekend.

There is no need to double clutch with a modern synchromesh gearbox and especially with a dog-ring straight-cut gearbox. You don't even need to use the clutch with those.

 

It is benefitial to double-clutch a car in an endurance race in order to save the gearbox. Although probably not needed most of the time.
and I believe driver operated clutches will not last ten more years, most road cars will probably have either automatic or manumatic, sequential gearboxes. Then we can all start left foot braking hehe

 

Hehehhe... I had always heard both of those terms and it was one of those "but was afarid to ask" kind of things. Come to find out NOW that I had been doing it for a while, but not becaus eI was track or street racing. I had a compression leak and the only way to keep the car from stalling when in neutral was to keep a toe on the throttle, i.e. when I would brake through the gears (as I do normally... less brake wear), I would H&T... actually it was more of a left & right, but the same concept.

Never be afraid to ask.

J.C.

 

I heel-toe downshift whenever possible. Sometimes it's hard with dress shoes (they make us wear a monkey suit & tie at work), but I still try.

As for double-declutching: I do this only in the morning, on the first couple of 1 to 2 UPSHIFTS. The shifts are smoother then. Yes, it's slower, but you should be taking it easy when you first drive the car anyway!

-Z.

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by GOBOGIE:
<strong> </font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by 944Fest (aka Dan P):
<strong>Hmmmm.. my technique is a bit different, but maybe I'm doing something different. I roll my right foot so the right side of it is bringing up the revs while the left side of it is braking. The left foot is busy on the clutch. Ideally, when the clutch comes up from a downshift the RPMs are there to meet it, and no clutch disk wear happens.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Nope, that's how I was taught too!</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">I started to try and learn yesterday, and this is the way I did it. I have larger feet, so I really can't angle my foot, and rolling it over just feels more natural. A little sloppy, but I nailed some of them perfectly. I noticed that I'd only do it down to 3rd gear though, cause by that tiem I'd be going slow enough to pop it in neutral and just wait for the light.

 

Heel and Toe most of the time, per Dan P and GOBOGIE. But I don't do it all of the time. To me, H&T is more for performance driving,or at the very least "spirited" driving and "casual" driving doesn't have the same rhythm. (Did I spell that right?) So as not to pick up any bad habits, I'll cruise neutral or whatever else while driving casually.

Never double clutch. Nothing against it, but it just seems time consuming to me. ...less efficient.

 

"- approaching a corner, start braking...
- clutch in with your left foot, gear to neutral, clutch out...
- twist your right foot in whatever way you feel natural with, so you can stomp on the gas pedal while still braking. Then just rev it
- clutch in, downshift to the appropriate gear.
- clutch out and apply gas as necessary"

_________________________

My first question was - "Why clutch in, neutral, clutch out, clutch in, gear, clutch out ?

Seems like an unnecessary step ? What is the purpose of letting the clutch out and going into neutral ? What does that accomplish ?"

I found the answer:

There is a countershaft in your transmission that double clutching is concerned with. Knowing tranny internals is required for this to make sense. The short of it is that you have synchros in your tranny that make double cluthing not required.

The basics of tranny internals are that you have an input shaft to the transmission. The clutch connects/disconnects the engine from this shaft. The input shaft drives the countershaft of the transmission via a gear. The countershaft spins the opposite direction of the engine and that is where "counter" comes from. The countershaft is next to the output shaft of the transmission and has a series of drive gears on it. The output shaft of the transmission has a series of the reciprocal driven gears. The countershaft, when engaged to a gear, drives the output shaft in the opposite direction of the countershaft, which is the same direction as the input shaft.

All the drive gears are more like rings with teeth on the outside that spin around the axis made by the countershaft. When stopped in neutral with the cluth engaged, the engine spins the clutch which spins the input shaft which spins the counter shaft. None of the drive gear rings on the counter shaft are engaged to the counter shaft so the countershaft spins inside the drive gears. The drive gears have their teeth engaged with the (driven) gears on the output shaft. The driven gears are always connected to the output shaft. In this case, all drive gears, driven gears and output shaft are not moving/spinning.

When you want to move, you need to connect one of the drive gears to the countershaft. This is done by disengaging the clutch, then using the gear shift lever to slide a gear along the countershaft until grooves on the inside of the drive gear match up with grooves on the countershaft. One way to get things lined up is to have everything stopped: input/countershaft not spinning and drive gears not spinning (which implies driven gears and output shaft not spinning.)

If you disengage the clutch, the engine will not force the input and countershafts to spin. No input force on inputshaft/countershaft (they are hooked together, remember) makes it much easier to get the gear ring (which ever you want) to side over the grooves on the countershaft.

Once the gear is selected and engaged, releasing the clutch allows the engine to spin the clutch, the input shaft, the countershaft, the drive gear, the driven gear and the output shaft.

Once rolling, keep in mind that the output shaft of the tranny is permanently fixed to the rear wheels of the car. If the rear wheels are moving, so is the output shaft of the tranny. If the output shaft is moving, so are the driven gears and the drive gears. Drive gears are always connected to the driven gears, just not necessarily connected to the countershaft.

Say we are rolling in 1st gear, with engine connected to clutch, connected to inputshaft, connected to countershaft, engaged to 1st drive gear, which does torque multiplication via some ratio to the 1st driven gear, connected to the output shaff, connected to the rear wheels.

If we want to shift to 2nd, we need to get the counter shaft disengaged from 1st and engaged to the 2nd drive gear. You have a spinning shaft (the countershaft) and a ring gear to engage (the one corresponding to 2nd gear). The problem is that, due to the different gear ratios between 1st and 2nd gear, the 2nd ring gear (drive gear) is spinning more slowly than the 1st driven gear. So, when you select the next gear, the countershaft has to be slowed so that the grooves on 2nd ring drive gear will line up with the grooves on the countershaft.

Normally, shifting is done by disengaging the clutch which lets the input and countershaft "free wheel" with respect to the engine, then de-selecting the current gear. By deselecting the current gear (neutral) and disengaging the clutch, the input and countershaft can spin freely, but they also slow down as there is tranny friction to slow them. At the same time, you can select 2nd gear with the shift lever. When the grooves on the countershaft line up with the grooves on the 2nd drive gear, it will "go into gear". The difference in spinning speed between the countershaft and drive gear can determine how long it takes for the grooves to line up and "fit in". Also, since the input and countershaft are just spinning freely, cramming it into gear just causes an abrupt slow down of the input and countershaft which don't weight that much so there isn't that much momentum. Upshifting is easy on the car because it isn't hard to slow down the input and countershaft since they slow down due to friction anyway.

Now, let's say we are driving along in 2nd and want to select 1st gear. The countershaft is engaged in 2nd gear which is driving the output shaft via the driven 2nd gear. The 1st gear driven gear, though, is spinning much faster around the countershaft, but is disengaged from it.

To downshift, you disengage the clutch which lets the input shaft and countershaft freewheel. They are spinning however fast they need to to keep up with the 2nd gear ratio because we were in 2nd gear. When we select neutral, the countershaft and input shaft get to free wheel again. However, the 1st gear pair is spinning like crazy (very fast) because were were going a speed which is way fast for 1st gear. To select first, the countershaft and input shaft have to speed way up to get the grooves on the countershaft to line up with the quickly spinning 1st gear drive gear. How is this accomplished?

In modern transmissions, the gear pairs and countershaft have synchronizers (synchros) which come into play as a gear is selected. As you select 1st, there is friction between the countershaft and the 1st gear drive gear which spins up the countershaft to the speed of the 1st gear drive gear. This makes alignment of grooves in the countershaft and drive gear easy, quiet and fast.

In old trannys, or in worn trannys, the synchros may not have much friction or none at all. Then, you need to spin up the input and countershaft manually. To spin them up manually, without being in a gear, you select neutral, then let the clutch out (engage it). If you blip the throttle, it will spin up the input/countershaft and, if you do it well, you will then be able to select the lower gear.

The idea of double clutching is to always select netural before a downshift, blip the throttle, then clutch in, then select the lower gear. This is mean to either save your synchros or to be used on trannys that don't have synchros.


http://www.nsxprime.com/FAQ/Track/highperfdriving.htm

 

I heel-toe on the street every opportunity I get.

Sam