Rev Matching / Double Clutching

[some6uy008]

Hi, I'm a newbie at standard transmisiion cars and I hear those terms a lot but I'm not sure what they are. Can someone explain to me what it is and their benefits

[Xaqtly]

Rev matching is a technique used to match the engine speed to the gear you're about to downshift to. There's a few ways to do it but one of the more common ways is "heel and toe"ing. An example would be if you're in 4th gear and you want to downshift to 3rd. So you push the clutch pedal in, "blip" the throttle (tap the gas pedal to push the RPM up), shift into 3rd gear and let the clutch out. Ideally, when you let the clutch pedal back out the engine RPM will be right where it needs to be to match the car's speed in 3rd gear, and the transition is very smooth. The "heel and toe" part comes in when you're trying to downshift and brake at the same time. So to downshift from 4th to 3rd while braking, you first push the clutch in, then angle your foot so that your toes are on the brake pedal and your heel is on the gas pedal. You apply pressure with the ball of your foot to brake, and blip the throttle with your heel to bring the RPM up. While you're doing all that, shift into 3rd, and then you can let the clutch out. That's a good technique when you're driving on a road course, because you usually have to drop a lot of speed before entering a turn, so by using this technique you can brake and put the car in a better gear for the upcoming turn at the same time. Also, if your foot or shoe is wide enough you can use the sides of your shoe to do the heel and toe technique instead of actually using your heel and toe. It works the same way, but you use the left half of your shoe on the brake and lean the right half on the gas pedal to blip it instead. Double clutching isn't necessary in today's cars because of synchros. Double clutching is basically rev matching but in a much more involved way - First you push the clutch in, pull the gearbox out of gear and into neutral, let the clutch back out, then rev the engine, push the clutch back in, put it in a lower gear and let the clutch out. It's the same thing as doing standard rev matching as described above, but it take three times as long to do and it's completely unneccessary. It's useful if you're driving a tractor though.

[Xenonk]

double clutching is still a common practice in some older race cars to maximize braking and engine braking.. it's also a way to what is known as "feather clutch kicking" to keep the revs up high.. you'll see most of that through stunt driving techniques. The benefits of the rev-matching/heel-toe technique is to lessen the impact of the gears coming together, less of the clutch plate getting beat up, less of the brake pads and rotors (if heel-toe) from getting "chunked or hot spotted", and your syncros will last longer because they will do less of the work to rev-match for you. These techniques will keep the tranny and the rest of the drivetrain happy and live a longer life. Keefe

[S4]

Check this link for a video of some crazy heel-toe action: [URL=http://www.teamsmr.com/movies/2003%20Sears%20Point%202%20Lap.wmv]Click me![/URL]

[Stacie]

I can rev match, but I usually double clutch downshift...although I'm not really certain why, because there's not really any mechanical advantage to it...except maybe it feels cooler. Makes for smoother downshifts and most excellent for faster turns.

[rc0032]

[font='Times New Roman']Someone (today I believe) mentioned they were a moderator on a message board about driving stick. Can you post that boards url? [/font]

[Stacie]

It was [url]www.standardshift.com[/url] Don't know what that website is, but there's the URL.

[rc0032]

[font=Times New Roman][size=3]So what I was getting at is this thread has a good video of toe and heal[/size][/font] [font=Times New Roman][url="http://standardshift.com/forum/viewtopic.php?t=1075"][u][color=#800080]http://standardshift.com/forum/viewtopic.php?t=1075[/color][/u][/url][/font] [font=Times New Roman][/font] [url="http://www.sierranorth.com/downloads/heel_toe.MOV"]http://www.sierranorth.com/downloads/heel_toe.MOV[/url]

[Xenonk]

I have my own video of my heel and toe action (I mounted my [url]www.chasecam.com[/url] under the driver seat on the WRX). If anyone wants to see how it's done, you can just PM me your email so I can send you guys the file and a little bit of my autocrossing in-car-and-out-board camera. Btw, that video isn't all that great (bad hand positioning too on the steerining wheel and sloppy footwork).. I'll put up a link of my WRX heel-toe footwork.. just excuse me of my hairy legs :p Keefe

[Xenonk]

Right-click the link and do a "save-as" please. [URL=http://evasionoftruth.com/videos/]Xenonk's footwork[/URL] This was done back about 2 years ago on my WRX.. I just slapped some stuff together of my autocross run, and how I preposition my feet.. (yes, there are times when I put my right edge of my foot on gas while braking, noobs, dont try this at home.. it's one of my autox techniques a variation that I tried to emulate left foot braking). The heel-toe stuff is at the end of the video (when you see that I push in the clutch, that's when I am shifting.. but notice my foot is still on the brakes as I am coming to a stop)... on the very last part of the video, I am downshift rev-matching for a smooth acceleration.. I double pump the gas for two reasons: the 1st is to 'rev-match'.. the 2nd pump is the acceleration pump, it's to make sure when the moment I let off the clutch, the flywheel should be spinning up and creating some momentum and the clutch engagement should have NO JOLT when you let off the clutch. Be smooth with the let-off on the clutch.. you can be fast with the foot, but be smooth.. easy in, easy on out.. the car is not a $2 whore. Enjoy the car. Enjoy:

[Xenonk]

[quote name='rclark0032'][font='Times New Roman']Someone (today I believe) mentioned they were a moderator on a message board about driving stick. Can you post that boards url? [/font][/QUOTE] See my link for my video on my previous post. Keefe