Question: Defining the "Perfect Shift"

[Kakkyo]

I know that in the world of performance driving there's an "urban theory" that between automatic and manual transmissions, there's a certain amount of calculated power loss as the flywheel power is being shifted through the tranny and then to the wheels.

The supposed power loss numbers are as follows from what I have read:

Automatic: 20% - 35% power loss
Manual: 5% - 20% power loss (percentage is proportional to driver skill)

I have always wondered: What is the definition of a "perfect" shift? Supposedly, F1 and pro race drivers can hit the range of a 5% power loss versus us common folk who lose 10% - 15% on a daily basis.

Can someone help sort this odd thought that just randomly came into my mind?

[blackzx3_13]

F1 drivers have computer controlled semi automatic gear boxes. That is how they get thier "perfect" shifts.

[Majik]

What? I think you are thinking of the power loss caused by turning the drivetrain. It has nothing to do with the driver, but instead the layout of the drivetrain.

[Kakkyo]

Good point, lol... I did forget about that point. Though supposedly, they can even apply said perfect shifting to the streets (another urban legend).

Another point to stir the fire... On dyno runs, do the shifts (perfect or imperfect) change how the dyno results record out?

[POS Racing]

Another point to stir the fire... On dyno runs, do the shifts (perfect or imperfect) change how the dyno results record out?

Nope but nice try. The engine is capable of a certain amount of power how well you shift the transmission while on the dyno does not decrease or increase the motors potential.

The basic key to a decent shift is to get it done quickly and get back in the gas as soon as you can.

[Miatamoto]

I'm with Majik. The percentage of losses has nothing to do with the driver and everything to do with the drivetrain.

That said, it has no effect on dyno numbers. Plus, you usually do a dyno pull in a single gear with no shifting.

[Kakkyo]

Sweet, much thanks for the enlightenment, everyone. At least it kills that urban legend from doting in my exhausted brain.

[POS Racing]

Sweet, much thanks for the enlightenment, everyone. At least it kills that urban legend from doting in my exhausted brain.

Where did you find this "urban legend"??

[Kakkyo]

Memories of hanging out on G2IC and Club Si back in 2002 - 2003.

[Majik]

Oh well that explains it. In hondas they are somewhat held back by the shift. Because of the roller bearings in their flywheel the shift can control the power level. That might be the connection with F1 and the BAR honda team.

[Kakkyo]

LOL, you make it sound like my former roots in Honda were a bad thing, Majik.

[POS Racing]

Oh well that explains it. In hondas they are somewhat held back by the shift. Because of the roller bearings in their flywheel the shift can control the power level. That might be the connection with F1 and the BAR honda team.

[Kakkyo]

POS: Ironically, that image has a picture of the vintage Club Si forums before their revamp back in '04. LOL!

[altiain]

Oh well that explains it. In hondas they are somewhat held back by the shift. Because of the roller bearings in their flywheel the shift can control the power level.

And all this time I thought it was the muffler bearings...

[BAM!]

The basic key to a decent shift is to get it done quickly and get back in the gas as soon as you can.

you could shift without letting off the gas too kakkyo, just to make you think some more...muhahaha! im entertaining myself by doting your ehausted brain....

[Kakkyo]

you could shift without letting off the gas too kakkyo, just to make you think some more...muhahaha! im entertaining myself by doting your ehausted brain....

LOL, no way dude... I am sorely reminded of the crazy guy who installed the HKS 6-speed dog-mission that shifts clutchlessly. The sound of pulling gears just sounded awful... I have the video clip on my HD, if anyone wants to hear the terrible grinding from the guy's shifting.

[TheChadVIII]

Hah, I don't know why they don't make car transmissions like they do the newer street bikes. You can kick up or down a gear in the newer street bikes without using the clutch, if you're in the right rpm range ~500rpms out of 14,000, it'll go in effortlessly and noislessly. If you ain't in the right range it just simply wont go in, no grinding or anything, just locks you out of it until you hit the clutch.

But yea I've seen one of those HKS pieces of junk in action, awful!

[altiain]

Hah, I don't know why they don't make car transmissions like they do the newer street bikes. You can kick up or down a gear in the newer street bikes without using the clutch, if you're in the right rpm range ~500rpms out of 14,000, it'll go in effortlessly and noislessly. If you ain't in the right range it just simply wont go in, no grinding or anything, just locks you out of it until you hit the clutch.

Because those transmissions have straight cut gears, unlike the helical gears used for forward speeds in road car transmissions. Ever wonder why your car sounds funny (gear whine) moving in reverse at any speed? That's because reverse is a straight cut gear.

On motorcycles you typically won't hear the gear whine over the engine. In a car, where the gear's engagement area is usually much larger (in order to transmit more torque), that gear whine is loud. Street cars use helical cut gears because the sliding engagement of the gears is quieter, even though this requires the use of synchros for proper engagement.

Most purpose-built racing cars have "dog boxes", or transmissions with straight cut gears. They are stronger, shift faster, and can be engaged without the use of a clutch, but the transmission gear whine prevents them from being installed in road cars.

[Majik]

Well I was gonna post a video of a race tranny, but it wasnt as distinct as I thought. It is a cool video anyway so http://video.google.com/videoplay?do...99070825595194

[TheChadVIII]

haha it probably be noticable on anything other than /that/ ferrari~
that sucker sounds cool!