Clutching on Upshift: Unnecessary?

Oh for sure.  Just lift and jam that sucker in.  As a matter of fact, drain all that unneeded oil out of the tranny too.

Seriously though, unless you are running a constant mesh dog gear trans you will be clutching your upshifts.  We don't clutch the upshifts or the downshifts on the Gnome.  Look at a motorcycle trans and you'll see why.

With dog boxes you don't need to clutch - just get the revs close and the dog gears will slam into place under pressure.  It shockloads the entire drivetrain. 

There is a good image of the gears about 2/3rd down the page.
http://www.carbibles.com/transmission_bible.html

Exactly....the synchros on a stock trans will make you look like a hero for a short while....when they're gone, you're on your own. Unless you lighten the flywheel, can the revs drop faster than you can shift? Can you trust your ear to rev match closely enough? By the time it starts jumping out of gear, it's too late....I give the clutch a quick poke, just to decouple the driveline torque and rotational inertia in the engine....but then again I ain't winning...

The only team(s) that can get away with clutchless shifting would be the all-dog box bike engine cars, and the Angry Hamster showed what happens with a too-long shift lever coupled with iffy '80s Honda V-four transmissions.

I've been riding for 20 some years and have never damaged a motorcycle transmission shifting without the clutch, but synchro boxes are very much at risk without careful shifting.

You could do it if you lost the clutch- I once drove an old 911 across LA in traffic with no clutch (the 901 trans had its clutch release fork pivot ball unscrew)- but you wouldn't want to do it under race conditions. Plus, the shifts are pretty slow without the ability to decouple and move the gearbox internals quickly.

Technically, if you are rev match just right, you don't need the clutch.

I've driven plenty of cars that way.  It works but some are easier than others.  I am not fast at it either.

Snychros on the Z transmissions are a pointy ring that helps align the gears.  Emphasis on "helps" they grind off pretty easy. 

Nissan transmissions drive alright but seem to grind easier than I would like.

Mazdas seem to smoother. 

I could pretty easily drive my of 626 without the clutch but my Maxima doesn't like it.

I am sure a quick clutch free shift is a huge shock load to the transmission.

Not disengaging the clutch has to help keep it cool but it's gotta hurt.

Like other guys said, I am sure some hardcore race transmissions can handle this.  Most OEM transmission are probably gonna puke the guts or the clutch out.

We've blown 2 clutches out of the Z.  Wiped the friction material clean off one side of the disc twice.  First one was out of the parts car so it was not surprise.  The second one on the second race was a big WTF.

The current clutch has 2 races on it and it still looks good.

I say DO IT...what could possibly go wrong ...

But seriously you can only do that in a true racing transmission with straight cut gears...or a sequential

LOL. See, I knew you guys would have the answers. Thanks.

http://www.youtube.com/watch?v=OI2fGeL7DEE

It's a hell of a mantra, for sure. I'm trying to incorporate it into other areas of my life.

Our team solved this debate but getting rid of the pesky shifting entirely.  CVT FWT...or catastrophic FAIL (We're not sure yet).