Let me get this right.....

Okay, now that you've had a sampling of the advanced theories, let's try the basics.

At a basic level, heel/toe is a technique for doing two things at once: braking and shifting.

Let's look at the shifting part. When you start out with a manual, you depress the clutch, push the shifter into the lower gear (with the synchros matching the layshaft to the output), then release the clutch. Feel that jerk as the two sides of the clutch match to each other? That's because the engine isn't running the same speed as the drivetrain.

You can help that by blipping the throttle a bit when you shift, to make the two sides of the clutch spin at about the same speed before engaging.

This is useful anytime, as it helps you get more miles out of your clutch, and keeps the coffee from falling off the dash.

But on the track, that jerk from a mismatched clutch release is more significant, as it translates down to tires already at the limits of traction -- an additional load that can make the difference between a turn and "going for a spin".

The key, here, is that you don't have to be braking to match revs during a shift. Before you add the complexity of trying to brake and match revs, you need to practice rev matching by itself, until it becomes second nature.

After that, heel & toe just becomes a matter of learning to work the throttle with the side of your foot, and working the brake with the ball/toe of your foot -- again, things that can be practiced separately.

Once you get all the components, then you can start putting them together.

It's tons easier to practice the parts separately than to jump in with both feet, as it were.

In terms of it's usefullness on the street: Well, matching revs does spare the clutch. You do tend to downshift at turns. But usually you have time to do the braking separately, before the turn, then downshift and accel through the apex.

I only h/t the Ferrari, because it's so easy to do. I usually don't bother on the Alfa, because the pedals aren't well matched. And I don't on the EVO, because (a) the massive turbo makes rev matching difficult, and (b) that stupid hydraulic damper that Mitsu installed on the clutch makes smooth shifts nearly impossible. It may be no coincidence that EVOs have a reputation for burning their clutches quickly. What the heck were they thinking?

 

If all goes well, power up-shifts without clutch will work on conventional car transmissions. However, if you mess up a few times, there is a good chance you will chip a gear tooth. Typical road car transmissions use quiet running but weaker helical cut gear design. Race car and commercial truck transmissions typically use noisy but very strong straight cut gear design.

I power up-shift a Formula Campus with straight cut gears. As stated by others, just momentarily lift on throttle and at same time quickly and firmly pull up to next gear. Throttle lift is just a split second and you are back on full throttle as the shift click into place. The firm pull on the stick is not for pulling out of the lower gear, but rather make sure it click into the next higher gear quickly and positively. When done right, you will feel the gears slide out from lower gear easily and literally click into the next gear.

Formula Campus has a very robust transmission, but even then I only do it for 3-4 shifts where shift gate is straight line motion. 1-2 shifts although also straigtht line shift gate motion but have a 10% chance of missed shifts due to wider ratio. As for 2-3 or 4-5 dog leg shift gate pattern, typically will have a 15% chance of missed shifts on average. When you miss a shift this way, the sound is not pleasant. And if your transmission has helical cut gears, it can also get to be very expensive.

As for down shifts without clutch with conventional transmission to left foot brake, I guess others who do it must be infinitely better drivers than I, because I can never do it consistantly with a conventional transmission. With straight cut gears maybe not too embarrassing, with helical cut gears I would not even try. IMHO there is no point in risking gear and synchro wear, when heel/toe will work nicely.

Now if you talk about left foot braking and/or power up/down shifts without clutch on a sequential shift race transmission, then all are easy. Not only are the gears straight cut, they use "dogs" to synchronise similar to motor cycles. So all you have to do is throttle lift to up-shift, throttle blip to down shift. So you left foot is completely free to just brake. I left brake on the Formual Renault I race, which has a very robust 6 speed sequencial transmission. Only need to use the clutch during start.

 

I agree and with the other points you made.

Racing machines are different than street units so I'm just gonna stick to street. My father taught me how to double-clutch in my air-cooled VW. It helped the down-shifting (the only time a 'modern' car needs to double-clutch or rev-match) from 4th to 3rd when climbing a hill so the car and engine wouldn't suddenly lurch. It kept the momentum moving forward smoothly.

Double-clutching is great to know during spooky road conditions, like ice It allows you to smoothly downshift. If, for whatever reason, I need to shift from 2nd to 1st then a double-clutch is the best way to do it w/o grinding!

I can double-clutch while cornering and my PERSONAL preference is to let the engine slow the car down along w/the brakes. Because the car has slowed down it will be below it's power curve thus the need to downshift. Double-clutching smoothly gets the car there!

"Power-shifting" isn't worth the damage it can cost IMO -- so I like to spend my $ on other things than trannies, call me cheap. Also, synchros are engineered to engage in a certain amount of time. Engagement that's too quick WILL shorten their lifespan! Clutch shifting quickly, particularly if you've installed a short-shifter (linkage) kit, can engage the synchros far too quickly and you'll hear grindage

A lightened flywheel does make rev-matching and double-clutching more difficult, BTDT.

My personal experience is that there is nothing wrong with learning how to rev-match and double-clutch, especially during slippery conditions.

Excellent page on the stuff:
http://318ti.org/notebook/shifting/index.html

And another:
http://www.urs4.com/technical/miscellaneous/Igor.html