Double Clutching? Why Bother

[onehundred80]

Why would you bother to double clutch (double de-clutch) when the car has a synchro gear box? This means you use the clutch twice when once was good enough. The correct application of the throttle in time with the clutch on our gearbox precludes the need for the double clutching used on the old fashioned crash gearbox.
If you want to save the gear box and clutch, put it in neutral and use the brakes when slowing or stopping as brakes are cheaper than a clutch.
Keeping aware of developing traffic movement ahead of you and slowing rather than breaking at the last minute saves gas, brakes, clutch and gearbox. It also may prevent someone running into your rear end.

[blackcrossfire07]

Downshifting will not hurt the car or clutch. I tend to take my foot off the gas and let the engine rev down. If I ever downshift I make sure I am going fast enough for the gear I am picking so I don't go into gear with high RPM's. I don't abuse the clutch or the brakes... I have 55K miles with plenty of brakes left.

[Goldwing]

Agree with Blackcrossfire07 -- if you know how to shift properly, the clutch should last a long time. Applying the brakes, revving it up, and popping the clutch doesn't do good for anything in the drivetrain. As far as taking your foot off the gas and coasting in gear (engine braking), I do it all the time. It improves a gas mileage. On occasion, with a long stretch of road leading up to a stopsign and no other cars around, I'll take it out of gear and let it coast for quite a while before applying the brakes.

[Bladecutter]

Originally Posted by onehundred80

Why would you bother to double clutch (double de-clutch) when the car has a synchro gear box? This means you use the clutch twice when once was good enough. The correct application of the throttle in time with the clutch on our gearbox precludes the need for the double clutching used on the old fashioned crash gearbox.
If you want to save the gear box and clutch, put it in neutral and use the brakes when slowing or stopping as brakes are cheaper than a clutch.
Keeping aware of developing traffic movement ahead of you and slowing rather than breaking at the last minute saves gas, brakes, clutch and gearbox. It also may prevent someone running into your rear end.

Where in the world did this rant come from?
Somehow, I doubt anyone actually double clutches their Crossfire, and I doubt most people on here have actually owned a car that required double clutching in the past 30 years that wasn't a tractor trailer.

BC.

[Beaner]

Originally Posted by Bladecutter

... I doubt most people on here have actually owned a car that required double clutching in the past 30 years that wasn't a tractor trailer.

BC.

Well onehundered80 is not a young as he once use to be so more then likely the car he owned before the crossfire was probably made in the early 60's and probably got it brand new, so maybe double clutching was necessary

[Franc Rauscher]

Double cltching is rather difficult in the crossfire anyway as the electronic throttle does not give one a precise instant throttle response.

That said, I double clutch when downshifting thereby putting less strain on the engine and clutch assy. Did a lot of that at the Dragon last week end.

I was driving another Crossfire last Friday on the Dragon with poor synchros. I could hardly downshift to second without double clutching. My experience with old 30's Fords and LaFrance fire engines came in handy.

And I too wonder the point, purpose, and origin of the rant.

roadster with a stick

[onehundred80]

Originally Posted by Bladecutter

Where in the world did this rant come from?
Somehow, I doubt anyone actually double clutches their Crossfire, and I doubt most people on here have actually owned a car that required double clutching in the past 30 years that wasn't a tractor trailer.

BC.

On another thread a couple of members stated that they D/C'd, I wondered why in the heck anyone would bother. I moved the topic here as suggested by one . Don't get your knickers in a knot.
As you can see we have an admitted Xfire D/C'er in our ranks already on this thread. So your doubts are mis founded.
The other members swore it saved their gearbox. My thought is that it would halve the life of the thrust bearing in the clutch in the least.

[Franc Rauscher]

Originally Posted by onehundred80

On another thread a couple of members stated that they D/C'd, I wondered why in the heck anyone would bother. I moved the topic here as suggested by one . Don't get your knickers in a knot.
As you can see we have an admitted Xfire D/C'er in our ranks already on this thread. So your doubts are mis founded.
The other members swore it saved their gearbox. My thought is that it would halve the life of the thrust bearing in the clutch in the least.

Theoretically it may save wear on the gearbox. But in truth i doubt it. The number of times you "miss" the shift double clutching probably grinds more off the syncs that you ever save.

It's just a cool technique that many drivers are too lazy or to inept to do fast and regularly. Especialy shifting up where it is less needed anyway.

Which is why I don't D/C going up.

As to the life of a thrust bearing, riding the clutch is the worst enemy of the thrust bearing. That said, the bearing cost less to replace than the syncs,,,or the gearbox.


roadster with a stick

[DSGoose]

I always double de-clutch the 1-2 shift when the gearbox is cold. Seems to be easier on me and the synchros. I rarely do it once everything warms up - it doesn't seem necessary.

Cheers,
Dennis

[Big Al]

"Knickers in a knot", c'mon now 180, how many on the forums users,(aside from you and I,) know what the h*** Knickers are anyway.
As far as double clutching a Crossfire, I drove trucks for 35 years, and when in my black limited beauty, I would not even think of double clutching,(a waste of time and knee energy, )at my age, that is not good.

[BlueStorm]

I practice DBL CLtchng all the time in the crossfire, it's not that difficult to do one you learn the timing on the throttle lag, it's much easier to do with the sprint booster but those are overpriced for what they do and cuase poor throttle resolution. I actually don't touch the clutch pedle during dbble cltching, what you need to practice is how to unload the tranny with the gas pedal, and then I manualy pull the shifter out of gear, then blip gas and shift into lower gears. if your wasting time pressing the clutch twice your going slower than the other guy and you will cause excessive wear to your throw out bearing and clutch..

down shifting I always blip the throttle to ease the loads on the syncros, remember they are usually softer brass, maybe some plastic parts too so the less work you make them do to keep the internal gears at he correct speeds for shifting the longer your tranny will last.

[Tazz]

These days, brakes are cheap and easy to change, so I rarely use engine braking. I downshift to be in the proper gear after braking, etc. especially on the track. I don't do the classic "double clutch" but I do match rpm's on downshifts so as to not upset the vehicle dynamics, and to have a smoother re-engagement of power.

[Bazzer]

Double clutching isn't necessary on a modern gearbox. If you want to master fancy footwork, concentrate your efforts on heel & toe. This can be useful on the downshift in a rear wheel driven car to match the engine speed to the road speed before engaging the clutch.

[onehundred80]

Originally Posted by Bazzer

Double clutching isn't necessary on a modern gearbox. If you want to master fancy footwork, concentrate your efforts on heel & toe. This can be useful on the downshift in a rear wheel driven car to match the engine speed to the road speed before engaging the clutch.

If you want to make things sporty on your way to the corner store, you can pick up a few pointers from this video. If you do not know what heel and toe and double clutching on the down shift is you can see it here, done by an expert.
Heel and toe and double clutching, requires fancy foot work. I'll stick to something simple, this makes it look like a routine in a Broadway show.
Heel & Toe + Double Clutching with Gary Sheehan - Car Videos on StreetFire

[Bazzer]

Originally Posted by onehundred80

If you want to make things sporty on your way to the corner store, you can pick up a few pointers from this video. If you do not know what heel and toe and double clutching on the down shift is you can see it here, done by an expert.
Heel and toe and double clutching, requires fancy foot work. I'll stick to something simple, this makes it look like a routine in a Broadway show.
Heel & Toe + Double Clutching with Gary Sheehan - Car Videos on StreetFire

Thanks for the video clip, its great watching it being mastered. Although I was taught how to use it on track by a professional instructor and to be honest, not really required to be used on a public highway unless you approach a roundabout whilst hard on the brakes.

Left Foot Braking is much easier to master and very useful for maintaining a balanced car during cornering, but you'll kiss the windscreen a few times during the learning experience.

[Franc Rauscher]

Originally Posted by onehundred80

If you want to make things sporty on your way to the corner store, you can pick up a few pointers from this video. If you do not know what heel and toe and double clutching on the down shift is you can see it here, done by an expert.
Heel and toe and double clutching, requires fancy foot work. I'll stick to something simple, this makes it look like a routine in a Broadway show.
Heel & Toe + Double Clutching with Gary Sheehan - Car Videos on StreetFire

Thanks for the video.
As one can plainly see, the double clutching was done on the rapid single and multi gear downshifts, not on the up shifts. One can also see that the driver was not doing it to save brake pads. Or the synchros.

Look at it from this perspective. The driver's function in the vehicle is to manage momentum and energy. He must communicate the energy forces of the engine and maximize the momentum forces of the vehicle to achieve the most efficient transmission of these forces into velocity. The more input axis's of control, the better he can do this. The faster he can communicate a new input the faster his overall velocity.

The biggest reason to double clutch when shifting down is to facilitate a more rapid engagement of the gears in the transmission. The only purpose is to improve control of the vehicle during aggresive manuvres on the track.

Wheels that are impeeded by braking lose steering control. Your front wheels have bigger brakes because they do the most work when slowing the vehicle. However, when their efforts are expended braking they are NOT steering.

Steering seems an important part of negotiating a turn, don't you think?

Engaging the engine to put drag on the rear wheels allows them to stay behind the forward advance of the vehicle making the front wheels stay in front where they belong. And allows the front wheels to do the steering part more freely.

Therefore any engine braking, especially with an open rear end, significantly helps to control progress over the ground. D-Double clutching facilitates that downshift, especially when shifting down more than one gear.
Getting the engine RPM's up quickly adds to the power available as the driver executes the turn. Downshifting not only adds control, it stores momentum energy of the vehicle into the flywheel and other moving parts of the engine/drive train.

Brakes dissapate this energy as heat. Said another way, brakes throw this energy away.

Management of the forces involved in the progression of ones vehicle can be controlled by devices mounted in the car. For those who bought manual shifters, we can engage our three pedals and the steering wheel, giving us four axis of control both accelerating and decelerating. Tha'ts 8 axis of control.

For those who bought push and go, push and stop Auto, you have only two pedals and a steering wheel. You can't use the tranny all that well for rear wheel control so you actually only have 4, maybe 5 with a good tranny, inputs to your vehicles movement over the ground.

That is why a good driver, who knows how, can get an underpowered manual to keep up with an overpowered auto in the twisties. Don't believe me?

Ask a few SRT6 owners who tried to keep up with me at the Dragon.


roadster with a stick
The way it should be

[Mike-in-Orange]

My first car was equipped with a manual gearbox and my father taught me how to double clutch when downshifting. He used to race a fair bit in Belgium before coming to the States back in '55 with mom, my older brother and two older sisters. He spent a fair bit of time with Paul Frere, before Paul became famous as a race driver (class wins in the Mille Miglia, overall at LeMans, etc) and journalist. I've been using this technique ever since, and that first car (a 1974 Dodge (Mitsubishi) Colt GT) went 198,000 miles with only a handful of adjustments to the clutch. Later on my 1984 BMW 318i needed the thrown out bearing replaced at 145,000 miles but the clutch itself was still going good when I got rid of the car at 189,000 miles. I'm either incredibily adept at the task, or it simply ain't hurtin' nothin'

With the Crossfire my wife can hear me coming home as our house sits on the side of a hill overlooking the main road where, with clear traffic, I approach downhill in 5th and heel/toe and double clutch my way to 4th, 3rd and finally to 2nd to make the corner into our development. She can hear the Magnaflow exhaust ripping off those shifts and says even the dogs have gotten to know the sound - daddy's home!!!!

[BoilerUpXFire]

Originally Posted by Mike-in-Orange

She can hear the Magnaflow exhaust ripping off those shifts and says even the dogs have gotten to know the sound - daddy's home!!!!

And what a sweet sound the magnaflow is

Althought I do not think my new neighbors 3 week old baby likes it much