What is it, first of all? What does it do? And how/ when do you do it?

the explanation on this one is kinda hard to write out... I would recommend searching the site for someone that has already explained it.
The purpose is to RPM-match and pull you out of turns at a higher speed....
It is NOT intended for 1/4 mile races as Fast and the Furious wants you to believe

Just in case you are too lazy to search here's a short explanation

Double clutching is where you press the clutch petal to take out of gear release the clutch pedal, press it again to put it in the new gear.

Its purpose is to match the revs of the gear used to change gear with the gear providing the drive to allow them to mesh. This technique not generally required with modern gear boxes since they have synchomesh gears that do this rev matching for you.

Some racing gear boxes to not have synchomesh and older cars my not have synchomesh on 1st gear and reverse.

Even with synchos, double clutching is occasionally useful for getting ino 1st and reverse particularly on the WRX which is not the easiest manual gear box to drive.

You will often see double clutching mentioned with heal and toe shifting. This is a racing downshift technique where you blip the throttle between the time you disengage the current gear and reengage the next gear say from 3rd to 2nd. The idea is to avoid engine braking as the new gear comes into play by getting it up to speed before you engage it so the engine doesn't have to drag it up and consequently loose speed. The heel and toe part refers to what you do with your right foot since you need to brake and blip the throttle at the same time. With synchomesh you can heel and toe without the double clutch.

Double clutching is more popular with non-syncro'd dog boxes, but it can also limit wear on syncos in our trannys as well. Gary Sheehan double clutches when racing. Check out the second video down on his video page (the one pointed towards the foot box), and you get an idea of what double clutching is. Obviously Mr. Sheehan does it MUCH better than most, but you get an idea none the less.

http://www.teamsmr.com/html/videos.html

-Chris

Thanks guys. This seems sort of complicated for me lol.

ok paul walker

wow, cool video

The purpose of rev matching is to get the engine to match transmission speed. Its as simple as that; alot of people look at footage's of this in action and are confused, and tend to think its difficult. But really its not once you understand its purpose. I do it quite a bit when I'm RR and can tell you from personal experiences, I do it to save my transmission, by double clutching the shift is slightly delayed allowing the gears to lineup and the synchros to open up. When your RR the transmission speed is constantly going up and down and sometimes you will have a hard time getting into gear with just a single clutch, you can sometimes hear the synchro's grind a little.

The trick behind doing the heel toe action is you really only worry about balancing the braking, slowing your car down enough to make your turn. As far as the engine reving up, all that matters is you get the rev limiter to bounce up as high possible without redlining it so that once you have finished double clutching and have gotten into gear the engine rev will match the transmission speed. So basically getting it up as close to redline the more time you will have to get into gear. Because I'm just a weekend RR and its difficult to keep an eye on the dash at the sametime while I'm trying to setup for the turn I like to double clutch and heel toe twice just to make sure.

Hope this helps!

Enjoy.

C

I know this is off topic, but I gotta know if you got your name Mushashi from that television show that has the same name.


Jason

I know this is off topic, but I gotta know if you got your name Mushashi from that television show that has the same name.


Jason


No I didnt, to be honest I dont even know what that show is. Its kinda a long story, but I was looking for a cool screen name since I RR, and remembered the Japanese Samauri Musashi, it kinda fit, I'm not actually the Musashi with the sword, but with cutting corners, thats me; and since on my other forum's my sign is "cutting corners w/a butter Knife!" it kinda fits.

Thanks for asking.

C

Double clutching is more popular with non-syncro'd dog boxes, but it can also limit wear on syncos in our trannys as well. Gary Sheehan double clutches when racing. Check out the second video down on his video page (the one pointed towards the foot box), and you get an idea of what double clutching is. Obviously Mr. Sheehan does it MUCH better than most, but you get an idea none the less.

http://www.teamsmr.com/html/videos.html

-Chris
wow the bmw in the last video just blocks and hits him

Damn, the WRX in the vid sounds like a beast

When engine RPM reaches the gear at speed its called the friction point.
so if 3500 RPM in 3rd is 45mph then the friction point for 45 and 3rd on flat ground is 3500rpm.

You dont even need to use the clutch if you find the friction point. The gearshift will just slide into place.
***WARNING*** Dont do this on your WRX first, its a pain and the WRX is more difficult than most and you WILL grind badly if done incorectly.

Man, I need someone to show me how to do this.

wow the bmw in the last video just blocks and hits him


You noticed that too? Punk BMW drivers. I've never met one I like!

-Chris <---- hides photos of the E36 he owned prior to his WRX... :p

I'm new at stick so I may just not be capable of understanding this yet but let me see if I got this right because I find it very interesting:

engage clutch go into neutral and disengage clutch - clutch again go into new gear and disengage?

Is that correct? If so, is this because the engine continues to rev high while in neutral as opposed to having the clutch in the entire time you shift through to the new gear?

Thanks for bearing with a newb ;) really cool vids btw!!

I'm new at stick so I may just not be capable of understanding this yet but let me see if I got this right because I find it very interesting:

engage clutch go into neutral and disengage clutch - clutch again go into new gear and disengage?

Is that correct? If so, is this because the engine continues to rev high while in neutral as opposed to having the clutch in the entire time you shift through to the new gear?

Thanks for bearing with a newb ;) really cool vids btw!!

Yes that is how you double clutch assuming you mean "press the clutch pedal" by "engage" and "release the clutch pedal" by disengage.

but no it is not "because the engine continues to rev high while in neutral". It only does that if you keep your foot on the gas pedal while changing gears which generally you should not do.

The reason is to allow the new gear to spin up to the "speed of the car" so that the gears can mesh easily. In modern gear boxes the synchromesh gears do this automatically so double clutching is generally not necessary. Unless you are a racer you would probably only use this technique occasionally to get into 1st or reverse since the synchros on those gears can be less effective and on some older cars, non existent.

how is the new gear going to spin up to match the engine rpm if you're in neutral though (between the two clutch activations)? I may just not know enough about transmissions in general to grasp this... I need to find some documentation on it.

Releasing the clutch pedal spins gears.

http://auto.howstuffworks.com/transmission4.htm

Tim