Heel Toe Question

Where does the help/protection occur in the process of a proper heel toe shift? Is it during the shift from higher gear to neutral? From neutral to the lower gear? Or both? Is the higher rev "blip" needed when you disengage the higher gear, or just before letting out the clutch in the low gear?

If you hold the clutch in the whole time, the only thing it does is allow you to downshift without upsetting the car and reduce wear on the clutch when you let it out in the lower gear. If you don't blip, when you let the clutch out the engine is spinning a different speed than the transmission input shaft so the clutch has to slip a lot to speed up the engine to meet the transmission speed. This also slows the whole car down a bit. If you "double clutch" while you downshift, i.e. blip the throttle with the clutch out in neutral before putting the clutch back in and selecting the lower gear, you also get the benefit of reducing wear on your syncros in the transmission, since they will not have to synchronize between the transmission input and output shaft speeds. This is largely unnecessary on modern transmissions but absolutely essential on older transmissions that don't have synchronizers like big delivery trucks, etc. The whole process with a double clutch downshift is 1. clutch in 2. gearshift to neutral 3. clutch out 4. blip 5. clutch in 6. select lower gear 7. clutch out (toe in a bit of gas to keep rpms where they should be) steps 3 and 4 can be blended a bit since the input shaft of the transmission has so little inertia.

Although it's not necessary on newer transmissions, a proper double clutch still reduces wear. If you learn to do it well, it happens quickly & smoothly and simply isn't a big deal. Note that the best "blip" while it's in neutral would be just a little above the rpm the engine will have in the lower gear.

So the most important blip is before the clutch release into the lower gear. There is still some benefit blipping before shifting into the lower gear. I take it there is no benefit blipping before shifting out of the higher gear. thanks

These guys explain it in pedantic detail... http://www.drivingfast.net/car-control/rev-matching.htm

Quotes source post: 10497561

I agree" great explanation. For our cars heel and toe downshift is used for smoothness to keep the balance front to rear under braking.

Very nice, I like pedantic. Thank you.

I don't double clutch when I heel/toe in the 996(or any other car for that matter), it's too much pedal dancing for me and I end up neglecting the proper racing line, full threshold breaking, etc. Also, I find it a bit difficult in the 996 to give the throttle the proper "blip" to precisely match revs. I usually come very close to matching, which is good enough for me. I think the drive-by-wire system in the 996 makes it difficult to really feel and judge the proper amount of throttle application during a blip. IMHO, the throttle pedal in the 996(not including the cable throttle in the '99s) feels a bit dead and nonlinear.

+996 on the egas. My instructor might chime in here and agree on my blipping deficiencies but I agree with Dream above that there is not really any tension feedback or tactile feel from the pedal. I get much more "feel" with a traditional cable set up.