dmcantrell

What is 'double clutching' ??

Flyin'Brian

Push the clutch in and shift out of gear, then let out clutch, then push clutch in again, and shift to next gear.

dmcantrell

What are the advantages of this technique (if any), as far as racing goes??

Flyin'Brian

the only reason I can think of to do this is if your syncros are worn out.
Or if you drive a big truck that don't have any syncros. (Race the Brown truck :lol: )

SFVetteman

The purpose of double clutching is to match gear speeds when shifting, especially when down shifting. Once upon a time, manual transmissions were non-synchromesh in all gears or non-synchromesh in 1st gear and this was the technique to use to avoid grinding the gears when shifting.

In a synchromesh transmission, when you shift gears, a tapered ring (usually made of brass) contacts the gear first and through friction brings the gear up to speed or slows it down so that the gear will engage smoothly without grinding the teeth of the gears.

If you were driving a car with weak syncro rings, double clutching might prolong the life of the transmission. Also, if a syncro ring breaks, double clutching may provide you with a way to continue shifting without immediate further damage to the transmission.

chuckster

I loved that STUPID comment made in "The Fast and the Furious" when the bald dude was mocking on the other guys racing technique...

He told him he should have been "Double Clutching" to gain speed... :lolg:
What stupid technical consultant gave then that line to use in movie.. :conehead


[Modified by chuckster, 2:02 PM 7/24/2003]

dmcantrell

OK guys -- thanks for the answers.

The reason I ask is this -- this weekend I was forced to watch 'The Fast and the Furious' (I hate that movie by the way) and there was a scene where Vin Diesel was ragging on the main character (Brian, I think..) for not 'double clutching' while he was racing his '10-second Eclipse'. The line from the movie was somthing like this "...You never had me. You were granny shifting, not even double clutching..." or something along those lines. I started a conversation with my friends that that comment was total :bs but I didn't really know the details of 'double clutching' to explain it to them.

At any rate -- thanks for the explanation, and I apologize for even mentioning that movie title on this forum.

--dc.

SleepieAce

My friends and I had the same discussion after that movie. The consensus opinion was that double clutching a race car is the best possible way to blow an engine and that some tech consultant somewhere is an absolute :conehead

:rofl: :rofl: :rofl: :cheers:

Special K

A good drag racer, just like a good truck driver (semi), doesn't need the clutch. It's all in the timing of the shift. A clutch is usefull when stopped.

Bob
:flag

geekracer

I remember that scene :lol: I also remember when 3 sp trannys had syncho between 2nd and 3rd :sleep:

verskel

:iagree: ......and to add to the Vin Diesel / Fast 'n Furious movie......it's a whole 'nother ballgame to shift a '69 Dodge Charger vs. a Ricer Eclipse. ;)

Sometimes I'll double clutch my '68 just to make up the time it takes for my mile-long shift throws ! :lol:

chuckster

I used to shift without the clutch on my 85 Honda Civic all time.. It was fun. No grinding at all.. I had it to a science..

I am not brave enough to try it on my C5 :eek:
Anyone else do this???

Trey395

It's also used to keep the car in the peak RPM range while cornering...

GR8-LIFE

I've heard this before. Can you splain???

Fastlane

Why not simply rev the engine to ease the syncro strain during the clutch re-engage?

I see no reason to double-clutch, at all.

Special K

I'll make this real simple. The engine rpm must be the same while between gears as it will be in the next gear you put it in. If you go into the next gear and the rpm is 3000, then that's what the engine rpm has to be to get it in there without the clutch. Doesn't matter if you're down shifting or up shifting or speed shifting.

Bob
:flag

GR8-LIFE

I get it, thanks

Special K

Mark,

Just start out trying it real easy and leave your left foot on the clutch but not depressing it. That will be your security blanket. Practice makes perfect. Gradually over a period of time you'll be able to speed shift using this technique and in a close race it will make the difference. Ronnie Sox of 'Sox and Martin' (pro drags) never touched a clutch in a drag race.

chuckster

I am actually anxious to try it...

Do you lift the accellerator during the shift? If done properly...will it put any unnecessesary loads on the tranny or synchros?

I am wondering how effective this would be Drag racing...

Because if I am going to shift from 1st to 2nd at 6200 rpm and I use the clutch.. I will end up at some speed less than 6200..

If I don't use the clutch I need to shift much earlier to match the speed I need fo 2nd gear..
Don't I loose the benefit of the redline shifts?

SFVetteman

There’s speed shifting and then there’s power shifting. In speed shifting, some attempt is made to match the gear speeds. The quickest shifting drag racers use power shifting. Power shifting is done by keeping your right foot to the floor while yanking the shift lever from gear to gear. This is best accomplished with lightning fast reflexes and muscle working through a strong short throw linkage coupled to a strong close ratio transmission. Done successfully, it’s the quickest shift there is.

If your reflexes aren’t quick enough engine RPM gets completely out of hand and you won’t be able to engage the gear. Not enough muscle and you won’t be able to force it into gear quickly, as gear speeds are never properly matched with this type of shift.

Big cajones are usually required for this technique and a big wallet is a plus.