What exactly is double-clutching?

[dkbmx993]

proper downshifting is heel toe. similar to doubke clutch except left foot keeps clutch to the floor right foot applies brake. before you downshift you use the side of your right foot to tap the throttle to rev match without releasing the brake.


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[Mutant Racer]

Originally Posted by AmericanMuscleCars

I have no clue, maybe watch fast and furious 1. Vin Diesel talks about Granny shifting and double-clutching!

Everyone else described the double-clutching but Granny shifting is a generalization so it applies to a lot of things. It describes a person who drives a manual transmission like a lost and overwhelmed old lady.

ie....missing your shift points, riding the clutch, pedal mashing, over-revving before shifting, stalling, and so on.

[77rs]

You guys are too young!

[77rs]

All pre-war trucks were double-clutched. In fact, the Antique truck club of America's publication is callesd "Double Clutch".

[fz4k98]

Double clutching is not needed in synchro manual transmissions. The concept addresses the gear speed difference in a transmission when shifting gears. When the clutch is pressed in to upshift, the transmission gears are spinning at the gear speed you were in. The new gear will require lower spinning speed like the engine rpm.

Double clutching on a upshift slows the transmission speed by letting the clutch out and recoupling the transmission input shaft to the new engine rpm. If done right it sets the transmission speed to the needed speed for the next gear.

[Jim968]

People confuse double clutching with rev matched downshifting. Double clutching is no longer needed on modern cars as described above, so don't even bother with it.

Rev matched downshifting IS worth learning if you want smooth downshifts. Its critically important if you track your car and want to be fast.

[epkmvuoq]

We call double clutching,,,,,,,,,,,, dump clutch on street or mud,,, when tires begin to stop spinning and start to hook ,,,,, at this time hold pedal to the floor,push in clutch and dump it again to try and maintain throwing mud. When engine starts to bog push in clutch to build rpms and dump it again.
This is called a classic country DOUBLE CLUTCH !!!!!!

[epkmvuoq]

Originally Posted by epkmvuoq

We call double clutching,,,,,,,,,,,, dump clutch on street or mud,,, when tires begin to stop spinning and start to hook ,,,,, at this time hold pedal to the floor,push in clutch and dump it again to try and maintain throwing mud. When engine starts to bog push in clutch to build rpms and dump it again.
This is called a classic country DOUBLE CLUTCH !!!!!!

Also called tearing up your s##t

[90503]

Originally Posted by epkmvuoq

We call double clutching,,,,,,,,,,,, dump clutch on street or mud,,, when tires begin to stop spinning and start to hook ,,,,, at this time hold pedal to the floor,push in clutch and dump it again to try and maintain throwing mud. When engine starts to bog push in clutch to build rpms and dump it again.
This is called a classic country DOUBLE CLUTCH !!!!!!

lol...If you're a batter in a baseball game, you don't want to double-clutch your swing...and sometimes double-clutching a throw doesn't turn out so well......but in basketball, if you double-clutch, you might fake out the defender and get an open shot...lol...

[bw26ss]

ya, double clutching is like when you are going to shift to second, you basically rev and dump the clutch, this is very handy for chirping the tires in second or third, lol.

[epkmvuoq]

In a 1948 jeep you may have to double clutch that old 4 cylinder 4 or 5 times to make it out of a real bad mud hole. Keeping that tire speed up ! Lol :-))

[Norm Peterson]

Originally Posted by CamaroJoe96

Hello all, just wondering if some of you would like to chime in an enlighten me on this topic! I've tried doing research other places, but can't really seem to get a nice, straight answer along with an explanation. Basically, all I understand is that it has some thing to do with rev matching while down shifting, but apart from that I don't really understand the matter. The way I drive is putting the car in neutral while slowing down/coming to a stop, and then putting it into the appropriate gear based on my speed. Is this the right technique? And also, when should the double-clutch technique be used? Thanks fellas!
Joe

Double clutching is this ↓↓↓ . Minus the commentary, as double clutching still has merit.

Originally Posted by strych9

Double-clutching was the act of pressing the clutch pedal, shift to neutral between gears, release pedal, rev engine, press pedal, shift to next gear. Not very efficient.

Double-clutching is an obsolete method of shifting a manual. Before manual transmissions had synchronizers installed. Synchros do what double-clutching used to do: bring the meshing gears up to the same speed so that they could engage without grinding into each other.

To my knowledge, all modern transmissions have synchros, so double-clutching is not necessary.

Originally Posted by FaytalsCamaro

to be honest seems unnecessary in our vehicles due to technology advancement

Originally Posted by fz4k98

Double clutching is not needed in synchro manual transmissions.

Not as necessary, perhaps. But still beneficial to synchro life. When you completely disengage the clutch, the disc and some of the transmission parts won't be rotating at the right speed even if you give the engine revs a kick to match them.

What I also read in between the lines is a lack of understanding or sympathy for what synchros actually do, and too much willingness to assume that "technological progress" frees them from the burden of having to learn a skill.

Originally Posted by Jim968

People confuse double clutching with rev matched downshifting. Double clutching is no longer needed on modern cars as described above, so don't even bother with it.

Rev matched downshifting IS worth learning if you want smooth downshifts. Its critically important if you track your car and want to be fast.

Near as I can tell, rev matching without double clutching actually works best when there is a little clutch drag (not 100.0% disengaged). For hurried downshifts this does work, but when you're not in a hurry it's a little easier to get the revs for all those "in-between" bits matched with a double clutch.

There still is a time and place for double clutched upshifts even with fully synchronized transmissions. When it's cold (say, 25°F and below) and you are holding the engine revs down (like you should be doing), the tranny oil can be stiff enough to basically stop the gears from turning in less time than it takes to get past the neutral gate. It is very definitely advantageous to double-clutch and rev-kick the upshift to get everything back to "matched". Most typically, this is the first couple of 1-2 upshifts and has something to do with the wider gear spacing between those two.


Norm

[Jim968]

Originally Posted by Norm Peterson

Double clutching is this ↓↓↓ . Minus the commentary, as double clutching still has merit.










Not as necessary, perhaps. But still beneficial to synchro life. When you completely disengage the clutch, the disc and some of the transmission parts won't be rotating at the right speed even if you give the engine revs a kick to match them.

What I also read in between the lines is a lack of understanding or sympathy for what synchros actually do, and too much willingness to assume that "technological progress" frees them from the burden of having to learn a skill.



Near as I can tell, rev matching without double clutching actually works best when there is a little clutch drag (not 100.0% disengaged). For hurried downshifts this does work, but when you're not in a hurry it's a little easier to get the revs for all those "in-between" bits matched with a double clutch.

There still is a time and place for double clutched upshifts even with fully synchronized transmissions. When it's cold (say, 25°F and below) and you are holding the engine revs down (like you should be doing), the tranny oil can be stiff enough to basically stop the gears from turning in less time than it takes to get past the neutral gate. It is very definitely advantageous to double-clutch and rev-kick the upshift to get everything back to "matched". Most typically, this is the first couple of 1-2 upshifts and has something to do with the wider gear spacing between those two.


Norm

Under normal driving conditions the syncros will last the life of the car. No double clutching required. There is no purpose in attempting to extend their life. You paid for the syncros. Use them! Nobody advises avoiding 2nd gear in an attempt to extend its life.

If you’ve ever instructed students on the track who were attempting to double clutch, you’d understand why I advise against bothering with it. It ends up slowing them down and making them wonder why they’re getting passed by a girl in a Miata (real life example of a student I had in a Porsche 993).

If you want to develop the skill just to complete the set of skills in your tool box, then fine. Just realize that you’ll need it about as often as you’ll need a 50mm socket. And whatever you do don’t learn it at the expense of perfecting your skills for proper rev matched downshifting.

[Norm Peterson]

I guess we need to separate street from track, and maybe agree to disagree a little.

Originally Posted by Jim968

Under normal driving conditions the syncros will last the life of the car. No double clutching required. There is no purpose in attempting to extend their life. You paid for the syncros. Use them! Nobody advises avoiding 2nd gear in an attempt to extend its life.

That logic works quite well for the average driver who chugs around turns and ramps/corners anywhere from one to three gears too high. There's simply a lot fewer shift cycles involved, and the vast majority of those are upshifts (which are naturally more or less rev-matched as long as you lift a tad). It was pretty firmly instilled in me to take as good a care of things as could reasonably be done. You can probably call that a generational thing, a function of having parents who lived through the Depression of the 1930's.

Waste not, want not, as it were. Any presumed improvements in synchro durability simply isn't going to change that attitude.

If you’ve ever instructed students on the track who were attempting to double clutch, you’d understand why I advise against bothering with it. It ends up slowing them down and making them wonder why they’re getting passed by a girl in a Miata (real life example of a student I had in a Porsche 993).

I wish I was instructor level, but I'm not. Just a guy who works at driving smoothly and shifts a lot to keep the engine spinning where it's reasonably happy. Actually, I know I don't double-clutch the 4-3 out on the track, and just those two gears adequately covers everything from 50 to 125 or so (keeping in mind that I only have 315-ish HP to play with, and that redline in 2nd is only 65-ish).

"Attempting to" suggests that said students weren't particular familiar with either double clutching or rev-matching, and come from the world of mostly mindless street driving where downshifts are done only when the engine is lugging too badly coming out of a 90° turn at a residential neighborhood intersection. Of course they're going to be klutzy at it . . . no matter which method they were attempting to use. I'm going to claim an exception here, based on 40+ years and tens of thousands of double-clutchings worth of practice.

But just so you know, if I'm being a little extra careful I can get away with not using the clutch at all once I'm not needing to grab 1st . . . upshifts and downshifts both. Maybe fit that alongside your 53.5 mm socket .


Norm