What is Double Clutching?

[fsr]

Originally posted by malcolm
huh?

actually, it's a trick set-up where you actually have two clutch pedals.... much faster shifting...

ROFL!

Is that what they mean when they say dual plate clutch?

[rwd polak]

What do you mean huh,
i didn't feel like explaining it becuase it already has a billion times.

[Tuner]

Originally posted by rwd polak
What do you mean huh,
i didn't feel like explaining it becuase it already has a billion times.

Please don't explain, cuz your dman wrong.

[artika]

I see so many uber technical explanations for this.


Double clutching merely disengages the clutch in between shifts (ie. in nuetral) so that the input shaft matches the same rpm's to match evenly with (X) gear.

If you're in 4th gear @ 3000 rpms
What RPM would be needed to engage the car in 3rd gear?

Why wear your synchros or possibly damage bearings/u-joints/etc, etc. when you can just hit the throttle with the clutch out between a shift so that there is no jarring, no jerking, and no sudden change in speed/power on the drivetrain... and it helps tremendously in corners because a sudden change in wheel speed and or power diversion can cause a loss of traction.

Double-Clutching = The Arch Nemesis of a Clutch Kick.
It may take longer but on an endurance race where drivetrain parts are harshly used, it could be the difference between winning and loosing. Ever blown a 3rd/4th gear synchro? the most used, the most shifted-into gears?

Yeah.. and tranny rebuilds aren't that cheap.

I heel/toe and double clutch all the time.
What's trick is when you don't use a clutch to shift and just rev-match the gears. Not good on a tranny, but it gets the job done when you blow clutch slave cylinders (like me the other night!.. drove 20 miles without a clutch!)

[jasonaries]

that's IT! (endurance driving shading today's skills)

Now I'm starting to understand why high performance driving feels like a whole new world to me. I've honed endurance driving skills for 8 years and am now stepping into a whole new realm when I practice performance driving. Adapting to race conditions versus endurance conditions feels alien to me. hmph.... who'd ever thought.....

[Hubert Young]

I don't know what's been said here but here's my 2 cents on double clutching.

Double clutching is for gear box without sychros. When you are in neutral with clutch engaged, you spin the gears in the gear box but not the output of the gear box, so you car stays stationary but again the gears will be spinning with the engine. Revving the engine, the gears spin faster. The idea is to rev match so you have a smooth engagement of 3 components: the wheels, the gears and the engine. When downshifting, shift to neutral, blip the throttle to bring the engine and the gears up to the speed of your wheels, then put it into the lower gear, you would have matched the speed of all the three components: again the wheels, the gears and the engine. As a result, you put less stress on the drivetrain, mainly clutch and the gears in the gear box. Also the downshift would not upset the weight of the car, making the tire contact patch to the road relatively constant compare to non-revmatch downshift.

Gear box with sychros does not really need doubleclutching since the sychros are doing the work for you to match the speed of the gears. However, I still do doubleclutch sometimes because I found that it's quicker for me to do the rev match than wait for the sychros to do it for me... I am talking split seconds here... especially shifting to second or first... (or may be I just feel it's quicker, since I learned how to double clutch when I first learn how to drive and downshift, timing is better for me that way, I usually couldn't get it into first when drifting if I don't doubleclutch) It's not really critical though.

Hubert Young
Motorsport Dynamics S14

[blargonator]

i want to learn how to double clutch and i am always doing to foot work and hand motions in my classes. cant wait to take out the porsche in the summer (.....i feel like a old man) it just seems like something that i should learn early so i always have that skill. oh and with heel toe do you do these steps.
1) it is in 4th and 9,000. you start braking and it goes down to 7,000
2) you shift into neutral blip the throttle and put it in 3rd.
is that so you also have the car slowing itself down also from being in a lower gear? oh yeah
"Ever blown a 3rd/4th gear synchro? the most used, the most shifted-into gears?"
i hope not. my car is a 4 speed manual.

[scirocco]

Originally posted by scirocco
ok just read yellowboy's post and mine and you'll get it. let's say your redline is at 9,000 rpms and when you upshift the revs drop down to 7,000 rpms. now you're at the track in 4th gear at 9,000 rpms and you are approaching a corner. a second gear corner. this is what you do normally with good synchros:

1. foot on the brake, wait for revs to drop to 7,000 rpms
2. clutch in
3. blip throttle, rev up to 9,000 rpms
4. downshift to 3rd
5. clutch out
6. wait for revs to drop to 7,000 rpms
7. clutch in
8. blip throttle, rev up to 9,000 rpms
9. downshift to third
10. clutch out, and take the corner

this what you do with bad synchros, i mean REALLY bad synchros

1. foot on brake, wait for revs to drop to 7,000 rpms
2. clutch in
3. shift to neutral
4. clutch out
5. blip throttle, rev up to 9,000 rpms
6. clutch in
7. shift to 3rd
8. clutch out
9. wait for revs to drop to 7,000 rpms
10. clutch in
11. shift to neutral
12. clutch out
13. blip throttle, rev up to 9,000 rpms
14. clutch in
15. shift to 2nd
16. clutch out


see the difference?

now lets look at double clutch upshifting
you have turned the corner and you exit at 6,000 rpms in 2nd gear... this is what you do normally with good synchros

1. foot on accelerator until revs up to 9,000 rpms
2. foot off accelerator
4. clutch in
5. shift to 3rd
6. clutch out
7. foot on accelerator

this is what you do with BAD synchros to double clutch

1. foot on accelerator until revs up to 9,000 rpms
2. foot off accelerator
3. clutch in
4. shift to neutral
5. clutch out
6. wait for revs to drop to 7,000 rpms*
7. clutch in
8. shift to 3rd
9. clutch out
10. foot on accelerator

*not only is this technique slower and much more complicated, but during the time of your shift wand waiting for revs to drop, you lose speed, sometimes even four or fives times as much speed as tou lose in normal upshifting. so now you should see that this technique is slow and bad and good synchros are key to winning races and easy driving all the time.

listen people, I think i explained this well enough, the questions have been answered by malcolm and me so I think this thread should be closed. Either that or stickied... no... just closed

[blargonator]

you are on at some crazy hours. so am i. anyways still no explanation of heel toe.

[scirocco]

no i explained how its done a long time ago in the post two posts above this one i quoted it

[Ghost of Duluth]

Question is answered.