Sneeze2K

double-clutching would be even worse for the synchros when upshifting because you need to slow the input shaft down not speed it up. double-clutching is used for downshifts by accelerating the input shaft to the equivalent speed of the gear you are engaging. there is nothing wrong with skip shifting as long as you give the input shaft time to slow down before engaging the higher gear. if you are going from 1-3 give it a couple seconds to slow down and it should go in easier with less synchro wear.

xviper

This topic has been beaten to death for over a decade. Every time someone new comes along and takes a course or does a Google search or has been "skip shifting" all his life, they "don't understand why it's such a bad thing". Sure, there are ways you can skip shift and do no harm but for the most part, not everyone is able to perform this simple task "properly", so the general advice is to not do it. To lead someone who doesn't understand the concept into believing it does no harm and it's OK to go ahead and skip shift with complete impunity is misleading and poor judgement. Sometimes, a little information is a bad thing.

The following are 2 pictures sent to me over 10 years ago from one of the head guys at Honda USA, who was in charge of their technical division in Torrence, California. That department received every single damaged part from every S2000 and NSX in N. America. I knew him for many years and he sent this to me to post up to show S2000 owners the dangers of skip shifting. As a representative of Honda USA, he could only post up so much, beyond which, he was not authorized to do so. What he did was to be the final say as to whether or not a customer would be denied warranty claims at the time based on the damage incurred and how it was incurred.

This first picture shows a "normal" syncro. Note the pointy ends to those metal strips .................


This next picture shows a damaged syncro from improper skip shifting. Note the points have all been shaved off and are flattened ................


Now that most warranties are gone on S2000s today anyway, there won't ever be an issue with it being covered or denied. It's on your nickel, so please skip shift all you like. I'm sure everyone will know exactly how to do it right so this kind of damage will never occur.

Billman250

I have had plenty of S2000 transmissions apart for this reason.

The gear that is skipped TO will have the engagement side of that gear collar beaten to death, just as xviper posted.

The input shaft should be slowed incrementally with each gear and not by skipping, and I assure you your syncros will burn up in addition to the gear collar if you skip shift.

This had been proven by many here including a Honda engineer named woodwork who used to post here regularly. You can search for his posts.

thomsbrain

Rev matching the engine and rev matching the input shaft are two completely different things.

Rev matching your engine will do NOTHING to spare your synchros unless you are double-clutching, which achieves engine and input shaft rev-matching at the same time.

Rev-matching your engine spares your clutch and reduces transient shock to the rest of the driveline during clutch engagement.

Rev-matching your input shaft spares your synchros during gear selection with the shifter. Synchros exist for the sole purpose of "automatically" rev-matching your input shaft. Synchros will last a long time if you use them they way they are intended to be used: matching the speed of the input shaft to the output shaft, ONE RATIO AT A TIME.

If you skip gears, it has a similar effect on the synchros as over-slipping the clutch does on the clutch. Imagine driving slowly and shifting early but revving the engine to redline in neutral and massively slipping the clutch out for every gear change. It would destroy your clutch very quickly. That's exactly what skip-shifting does to your synchros.


The above post by spets describes what happens to the input shaft and synchros during skip-shifts and normal shifts. Read it and win.

thomsbrain

Not quite. Double-clutching can be used without the throttle blip during upshifts to match input shaft speed and save the synchros. It just happens to be of little value because in most cases the input shaft is already slowing down at a decent rate even without the double-clutch.

conzetts2k

Got it no skip shifting lol

BLAQ&GREYs2k

Three awesome answers from the big names I was hoping to hear it from. Thanks for shedding some light "on a topic that has been beaten to death for a decade", much like many topics on this sight.

A thought of question: The greater the change in gear ratio from the first gear TO the next gear, the greater the damage to the syncros due to the speed of the input shaft. Does your statement of skip shifting being bad apply to skip shifting to downshift from 6 @65mph to 4 to slow down into an off ramp? Here the gear ratios are much closer together so would you agree the impact on the sycros would be less than from 1-3?

If so then I think I can settle with skip shifting is bad depending on which RPM and gear you are in. Because what if I shift from 1st gear @20mph to 3rd gear? That wont do damage still will it? The input shaft is not moving nearly as fast as 1st gear @ 7k straight to 3.

AP1Driver

Do what you think is best, it's your car... My S is proof that skip shifting ruins synchros in this car: The PO (original owner) skipped 3rd daily from the day he bought it and the synchro's been grinding since 40k when I bought it.

SpitfireS

The only post one needs to understand(*) is post #7, by spets.
That's the explanation why it is bad.


(*)

un·der·stand
[sup][/sup]/ˌʌndərˈstænd/ Show Spelled [uhn-der-stand]
un·der·stood, un·der·stand·ing.
verb (used with object)
1. to perceive the meaning of; grasp the idea of; comprehend: to understand Spanish; I didn't understand your question.
2. to be thoroughly familiar with; apprehend clearly the character, nature, or subtleties of: to understand a trade.
3. to assign a meaning to; interpret: He understood her suggestion as a complaint.
4. to grasp the significance, implications, or importance of: He does not understand responsibility.
5. to regard as firmly communicated; take as agreed or settled: I understand that you will repay this loan in 30 days.


Now.. its never bad to ask questions.
But... suppose someone wants to learn how to drive.
First lesson in the car.
First question by student: "What's that round thing in front of me?"
Maybe... that person should not drive at all.
(get my point?)

james0933

Rowing through the gear without engaging the clutch is still ok, correct? Or not ideal?