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The Topic says it all......
What is Double Clutching?? and how do you do it??

I remember hearing it from Fast and the Furious.....
Does any char from ID ever do it??

Double clutchin is a technique originally created by truckers with bad synchros. It involves engaging the clutch for a downshift, disengaging it halfway through the shift, then engaging it again aand finishing the shift. It should never ever be used by a person serious about racing.

Dude you didn't know? That's why you lose the drags...granny shifting when you should've been double-clutching. Either by an inch or a mile, a win's a win. I live my life one Nos bottle at a time.

I'm fast AND furious.

jk

Alex

double clutching is used to downshift with cars with either bad synchros or no synchros. the technique entails depressing the clutch, put the gears into neutral, let go of the clutch, match rev, depressing the clutch again, downshift then match rev and release the clutch.
the reason to do this is that if you downshift with a car w/ bad synchros or no synchros you will get your gears to grind as you downshift. the match rev in the middle lets your downshift smoothly.
if you go to racing schools like skip barber, their open wheel cars do not have synchros so this techique is important. sometimes if you want to downshift to first gear, doing this would be useful too.

Thanx peepz... I understand the concept now...

But another Q arises now...... What is synchros??
What are some cars w/ synchros?? w/o synchros??

i know what it is but i cant put it into words so here ya go :

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

i love howstuffworks.com

For the people that are too lazy to click the link, here you go:

QUOTE

Information and images are taken from howstuffworks.com Manual transmissions in modern passenger cars use synchronizers to eliminate the need for double-clutching. A synchro's purpose is to allow the collar and the gear to make frictional contact before the dog teeth make contact. This lets the collar and the gear synchronize their speeds before the teeth need to engage, like this: The cone on the blue gear fits into the cone-shaped area in the collar, and friction between the cone and the collar synchronize the collar and the gear. The outer portion of the collar then slides so that the dog teeth can engage the gear. Every manufacturer implements transmissions and synchros in different ways, but this is the general idea.

you usually double clutch before going through a corner to keep your revs up or something like that..I could be wrong.


when you're shifting you're supposed match your revs wif you speed neways so bad syncros shouldn't be a problem if you know how to shift.

rally cars are not syncronized hehe, when the driver wants power he goes and get it ...rally is so nice !

A lot of current rally cars in the WRC have semi-automatic sequential shifters. Sequential in that you can't jump straight from 4th to 2nd without passing 3rd also, therefore there's only a lever for upshift and downshift. And in acceleration the transmission works as a racing automatic, so the clutch is only used when the rally driver downshifts.
Alex

I think double clutching can done without using the clutch by simply shifting out of gear to neutral, matching revs and then shifting down or up. It can actually be better for the car than using the clutch to shift if you know how to time it correctly.

...if you do that then you screw up your clutch plate. and if you can't get the timing right you'll grind your gears like crazy.

this is a REALLY bad idea.

i know a lot of race car drivers do it because it saves time and if you know your car well enough you should be able to do it smoothly

i'm talking abotu before SMG's

the M3 SMGs are "supposed" to be faster than manual or so they claimed. it uses electronic rev-matching to keep up eves when u down shift in turns. I whish i could try it someday cause everyone says is so good

You can also perform a "perfect launch" with the BMW SMG system, only once every 24 hours I think, and 10 times during the life of the clutch. But I hear the time it takes to shift is in miliseconds, which is pretty cool if it's true.

Alex

Yeah but you got to replace and I'd rather have something take a bit longer but I can use for over 5 years of my life then to use something a bit faster for 2 weeks of my life

I don't think you wanna have to replace any bmw part. I have an E30 325i and it costs me a bundle if I need to bring it into the shop to repair. and for newer bmws I'm sure it'll be 10 times more than what I'm paying heh. and esp cuz it's a special transmission system it'll be hella expensive to replace.