BOSS

I go on other auto forums and read a bunch of narratives and watch all kinds of videos etc. The one thing that is often brought up is "double clutching" while racing somebody in a straight line. I recently watched a video of an E55 vs. Z06 and the guy in the Z was double clutching supposedly.

Now, double clutching is just that I assume - double clutching. I'm thinking it limits the lag caused by gear switching to some extent, is that correct? Why do it in the first place? How does it help performance? Probably worthless in a car like a Maxima, unless it's heavily modded, am I correct?

Somebody please elaborate more on this.

Thanks

Terran

iTrader: (6)

It needs to be done in old army trucks and such that have no synchros. I'm not sure of the specifics, but it may simply be rev matching which is better for the tranny but not necessary.

Ceasars Chariot

iTrader: (16)

http://www.driversedge.com/dblcltch.htm

96explorerxlt

You can just throw it in the lower gear and rev up before letting the clutch engage, thats easier and much faster I think.

98SterlingMax

Ceasars link explains perfectly, remember it's for downshifting and saving wear on the synchros, don't know why someone would do it racing somebody in a straight line.

Terran

iTrader: (6)

Ok I just read that. Can somebody explain why you should let off the clutch in between? Normally I just rev match at the same time as I am shifting to whatever gear I'm going into. Is this bad for any reason? What do you guys do?

99se5spd

Thats what i do and ive always done and never had a problem.



It also helps you not loose your inertia.

98SterlingMax

The clutch is let out in neutral to get the gears spinning up to speed before engaging the lower gear, simply pushing the clutch in and blipping the throttle before letting the clutch out and after engaging the lower gear only saves wear on the clutch, not the synchros. That's better than nothing I guess.

mzmtg

iTrader: (11)

Watch these vids at The M5 Driving School to learn all you need to know about shifting and launching.

SteVTEC

I double clutch all the time, but not when accelerating in a straight line!

It saves wear on the synchros and the gear engagement is also a lot smoother vs just rev-matching alone. It takes a bit of practice, but after you get your brain hardwired for it, it's just as easy as any other shift. I only ground the gears once or twice while I was teaching myself. oopsie.


What's sad is when people say they double clutch when they don't even know what the hell it is, and when that isn't even what they were doing in the first place.

eckohb

iTrader: (4)

i remember in the fast and the furious, vin diesel saying paul walker was granny shifting instead of double clutching like he should have been...were they just trying to sound like they knew what the were talking about? seeing how you probably wouldnt double clutch in a street race?

endus

iTrader: (1)

You would never double clutch when you're upshifting. There is no point. The only thing it would do in a straight line race is slow you down and make you all jerky.

I double clutch pretty much all my downshifts now, except if I am really pushing it sometimes I will just revmatch. Once in a while if you're a little hot into a corner and trying to heel and toe the downshift it's a little too much to double clutch....but that's what syncros aer for anyway!

The advantage to double clutching is that with rev matching alone, the syncros still have to spin the layshaft up to the new transmission speed, but not the engine. With double clutching, the layshaft *and* the engine are matched to the new transmission speed so there is basically no wear on the syncros and you can get *very* smooth downshifts. You can even downshift into first gear with absolutely no jerk...but it's difficult.

Here's a great site which helped me to understand all this...

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

and in aprticular start on this page...

http://auto.howstuffworks.com/transmission3.htm

Brudaddy

iTrader: (2)

Double clutching and rev matching are two totally different things that give a similar result. While rev matching is easier on the tranny and the syncros, it is still harder on the clutch. Double clutching is letting the rpms match for the next gear you want to be with minimal wear on the tranny, syncros, and the clutch.

I know how to double clutch, but I usually just rev match. Depends on the setting though.