In another post I made, several people concurred that skipping gears while upshifting in the S2000 causes pre-mature transmission failure.

Can someone, preferably a mechanical engineer, explain this?

I had a Corvette before this, and for anyone that's driven an LS1 powered vehicle with the GM transmission knows that it tries to force you from 1st to 4th gear to boost fuel economy. I don't understand why this would cause more stress on the synchronizers compared to normal shifting... especially when some FR cars have this built in from the factory.

I've been skipping gears in my MY04 since I got it and my gas mileage has reflected my driving style. The transmission setup is slightly different in the S2000, so perhaps this has something to do with it? I let the revs fall a bit more when skipping gears and it's never really been an issue... just curious why people say this causes transmission failure...

If you've had your transmission fail due to this, post up as well!! I'd like to know the mileage when it occured, if Honda warranteed the work, etc, thanks.

 

Refer to this post for a technical explanation:

https://www.s2ki.com/forums/index.php?showt...dpost&p=4581588

 

Ah wow... exactly what I was looking for, thanks. The search never turned it up due to my key words.

For anyone else interested... here's a quick explanation by smyroad

"1) It was the result of not using 5th - Moving quickly through 1-2-3 maybe 4 and directly to 6th. No grinding sound during shifting.
2) Cause was supposedly mushrooming of the sleeve teeth due to the syncros handling the velocity difference between input shaft and output shaft. The sleeve is soft metal because the torque per tooth is relatively low. Problem is the push from the synchros is enough to mushroom the ends.
3) Honda mechanic fixed it by forcing it into fifth, requiring much more force than I was willing use.
4) Mechanic said this IS a PROBLEM in other HONDA 6 speed transmissions.
5) This is not caused by abuse - unless skipping 5th is a crime."

Ah well... no more skipping gears for me thanks to S2Ki.com Even though my MY04 does have the new carbon-fiber reinforced synchronizers

 

I've had 2 Vettes and a Viper. All 3 have had "CAGS" (Computer Assisted Gear Selection). As the phrase suggests, you must realize that in those cars, the computer knows when and when not to allow the skip shift. ONLY if the revs and throttle position and road speed are all just right, will it allow the skip.
On any other car, without computer assist, there is no assurance that a driver will know what the "ideal" parameters are for doing a skip shift. Invariably, the rpm, throttle position and road speed are NOT correct and doing such a shift can mangle the syncros.

 

Would that hold true for say a 6th to 4th downshift? Would double clutching help either scenerios?

 

Yes, however, a 6 to 4 downshift can be DOUBLY dangerous in that if you start out with too high an rpm and/OR accidentally hit 2nd instead, you will also risk a mechanical over-rev. You've heard of those, right? In ANY skip shifting, REV-MATCHING is critical. If you're not so good at doing it, then don't skip your gears.

 

When going up through the gears, after I'm finished accelerating, I select each gear and fully release the clutch up to the desiered gear (such as 5th gear in a 45 MPH zone, after taking it to over 40 MPH in 1st gear. Will this alleviate the problem?

Also, I often skip several gears while downshifting to pass or just for kicks. Right now my rev matching isn't perfect, because I'm new to the S and it's my first manual transmission car. Is the damage derived from downshifts of this sort as bad as the skipped gear on upshifting? (Assuming I was within 1000 RPM of the exact match)

 

Great thread, great pictures, thanks.

It looks to me like the issue is that the bearings are so good in the S2000 transmission that the main shaft doesn't slow down on its own once the clutch is in. If you VTEC through third, then go to sixth, the synchros have to slow it down all the way from 9000 to 3000. Rowing through fourth and fifth distributes that slowing through three sets of synchros.

That also explains why GM friction modified transmission fluid seems to clear up these transmission issues for a lot of people. Not only does it make the synchros work faster, it may also put more drag on a freely spinning main shaft so that the main shaft slows faster. That wouldn't necessarily be so great for a downshift, though.

This suggests another shifting technique that might theoretically work well for this transmission. Pop out of gear before the clutch is put in, drop the engine revs while the main shaft is still engaged, then put the clutch in to put the transmission into the following gear. Basically, double clutching without the first clutch. Anyone want to risk destroying their transmission in the cause of science and try this?

 

I think the link I posted before wasn't working as I expected. Here is what I really wanted to point out, quote by S2WOOOW:

[QUOTE]This tranny is designed differently than most trannies.

 

If done properly, skipping gears will not harm the transmission.