when to shift

This is extra helpful, I have been wondering about this when I shift while slowing down. I had a tendency to skip gear when I slow down while pressing the brake. Meaning if I am slowing down from 60mph at 5th gear, while pressing the brake, I slow down to 30mph and I put the gear from 5th to 3rd, skipping the 4th gear. This is what you are talking about, right? I am glad I only did it a couple of times and will avoid from now on.

Correct. Instead of moving the gear lever directly from 5th to 3rd, go from 5th to 4th to 3rd without engaging the clutch. It's so easy, even a caveman can do it.

As mentioned earlier, there is a service bulletin advising against the practice of skipping gears. Though there may be some people who seem to believe they are smarter than the engineers at Honda and believe it's okay to ignore such advice, or, they don't operate their cars with as much care as some other owners choose to, use your own judgment and consider the information carefully - especially in pre-'97 cars.

In 1997, the NSX received double synchros in 3rd & 4th gears. In 2005, the NSX received double synchros in 5th & 6th.
 
As mentioned earlier, there is a service bulletin advising against the practice of skipping gears. Though there may be some people who seem to believe they are smarter than the engineers at Honda and believe it's okay to ignore such advice, or, they don't operate their cars with as much care as some other owners choose to, use your own judgment and consider the information carefully - especially in pre-'97 cars.

I think its not so much that people want to outsmart Honda, but more that there is confusion for a lot of folks since every manual transmission works the same way essentially, and (for me) its the first time Ive seen an advisory like this.

In fact, what the guy above is describing (slowing down from 50 to like 20 for traffic or whatever and then shifting from 5 down to 3 to get rolling again skipping 4) is something I've always considered pretty normal and was actually advised to do so. Like here is a good example:

http://www.sdt.com.au/safedrive-directory-CHANGINGGEARS.htm

Note the FAQ:

1. Can you go from 2nd/3rd/4th/5th gear and straight into neutral or do you have to go through them all? Can I go from 5th to 2nd/1st?

Yes it is recommended that in a modern manual transmission you can skip gears when going up or down. For example; when accelerating you can if required change-up from 1st to 3rd, though 3rd gear may labour due to low engine revs.

So I think what is confusing to people (its confusing to me at least), is what is deficient in the Acura transmission that it needed that TSB and why?
 
You guys really confuse me now from the 2 posts above. What is the right way?

This is what I usually do- at 65MPH, I put it in the neutral ( coasting) to exit the freeway until complete stop by braking it. Is this normal to drive?
 
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The most sychro-friendly way is to just double clutch and rev match. If done properly, the synchros are theoretically not even in play.

This is really a discussion of minutiae. If you skip gears, it will save gas, but may, allegedly, cause additional sychro wear over the life of the car. Bogging the gears may also lead to extra clutch wear which is a more short term concern. Clutches are not cheap. Even if you double-clutch you are putting extra stress on the master & slave cylinders....sooo pick your poison. These are not all concerns unique to the NSX, but you seem to have opened quite the can of worms.

To the OP. Do yourself a favor and ask people cite sources for official information ("I read somewhere....." doesn't count), and pay most attention to those on this board who are qualified NSX technicians and/or have piles of experience breaking and rebuilding various components from racing.

note: I am not one of those people :)

NSX1: Could you or someone post a link to the TSB? Is it in the FAQ and I'm just retarded?

drtruong: IMHO there is nothing wrong with using brakes only to stop the car in normal street driving. Opinions may vary.
 
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...In fact, what the guy above is describing (slowing down from 50 to like 20 for traffic or whatever and then shifting from 5 down to 3 to get rolling again skipping 4) is something I've always considered pretty normal and was actually advised to do so...

Note the FAQ:
1. Can you go from 2nd/3rd/4th/5th gear and straight into neutral or do you have to go through them all? Can I go from 5th to 2nd/1st?

Yes it is recommended that in a modern manual transmission you can skip gears when going up or down. For example; when accelerating you can if required change-up from 1st to 3rd, though 3rd gear may labour due to low engine revs.

So I think what is confusing to people (its confusing to me at least), is what is deficient in the Acura transmission that it needed that TSB and why?

Mark, I agree that it is a pretty normal way of driving. Heck, I drove like that for most of my life (I'm 59 now.) Then, a couple years back, I was reading a thread here on prime about a guy who was complaining about having to have his transmission rebuilt because the synchros were gone. A discussion ensued about the TSB and gear skipping. I said to myself, "Oh shit! I do that all the time." I'd had experience rebuilding manual transmissions when I was younger and it immediately made sense to me, so, since I baby my NSX, I decided to stop gear skipping.

Since the synchros are a sacrificial item, I do whatever I can to reduce wearing them out. Besides eliminating gear skipping, I will go straight into neutral if I'm coming to a stop. I will sit at a stop for a few moments before putting it into 1st.


The most sychro-friendly way is to just double clutch and rev match. If done properly, the synchros are theoretically not even in play.

I wish I was good enough to do this.

NSX1: Could you or someone post a link to the TSB? Is it in the FAQ and I'm just retarded?

Richard, I looked for it, but so far, unsuccessfully.
 
Richard, I looked for it, but so far, unsuccessfully.

No problem. I was just curious if it contained any technical details regarding why they issued it. If they were questionable, I would have expected them to already be a problem with my car. Maybe it is, or was and has been fixed once. I haven't driven another 5spd NSX to have a good basis for comparison. None of the mechanic-types that have driven it (Barn Man included) have mentioned any maladies though.

I habitually heel/toe(when necessary) and rev match for downshifting. Double clutching isn't bad on upshifts, but not very practical unless you are driving pretty lazily and doing stuff like skipping gears. On the down shift it takes a little thought to actuall blip at the right time so as to get all the shafts & gears synched up. Of course I had an MR2 Turbo to practice on and I have a spare transmission for it that I picked up for about 1/10th of what an NSX tranny costs. :)
 
Mark, I agree that it is a pretty normal way of driving. Heck, I drove like that for most of my life (I'm 59 now.) Then, a couple years back, I was reading a thread here on prime about a guy who was complaining about having to have his transmission rebuilt because the synchros were gone. A discussion ensued about the TSB and gear skipping. I said to myself, "Oh shit! I do that all the time." I'd had experience rebuilding manual transmissions when I was younger and it immediately made sense to me, so, since I baby my NSX, I decided to stop gear skipping.

Since the synchros are a sacrificial item, I do whatever I can to reduce wearing them out. Besides eliminating gear skipping, I will go straight into neutral if I'm coming to a stop. I will sit at a stop for a few moments before putting it into 1st.

.

I wish I understood the physics of it more... If the car has come to a dead stop, I cant figure out why it would matter. If the car is rolling, but at a gear appropriate speed, it seems like it couldnt make a really big difference, although I can see how it would be a bigger difference than stepping back down through the gears.

That said, Im trying to learn the "right way" now. Sort of tricky! As everyone knows driving a manual has to almost become muscle memory for it to be routine. Once thats committed learning a new way isnt easy! :D

I never skip going up, so thats not an issue. Ive tried double clutching, but Ive just never been able to get used to that.

Still curious to me that Acura felt they actually needed to issue a TSB on this when no other manufacturer needs to. Whether or not it actually causes additional wear to the synchros, no other manufacturer that Ive seen has felt it was a big enough deal to actually issue a TSB.
 
One version of the alleged "TSB" is in post #6 of this thread: http://www.nsxprime.com/forums/showthread.php?t=74757

In my opinion, it looks more like an article from a monthly Service Department newsletter or some such.

As far as my $0.02 on the subject here...if we all should be so worried about synchro damage when skipping gears because we are driving lazily...what the heck kind of damage are we doing when we are driving hard??? I can't imagine that either shifting method, in moderation, is going to cause excessive damage to any transmission, let alone a sports car transmission.
 
I found a pretty good explanation of how this works. Reposted for your easy viewing pleasure. Link to full article at the bottom.


"normal" shifting:

1 engine turning at a slow speed, higher gear is engaged, layshaft turns at a slow speed (to match the higher gear)

2 clutch is disengaged, engine is now independent of the transmission

3 gear shifted to neutral, the layshaft is now independent of the driveshaft

4 blip gas, engine speed is higher (to match the need of the lower gear), layshaft is still turning at a slower speed to match the previously engaged higher gear

5 gear shifted to the lower gear, the layshaft needs to turn faster to match the lower gear, the synchromesh uses dynamic friction to match the speed of the layshaft to the speed of the driveshaft

6 clutch engaged, the engine is now connected to the layshaft, which is already turning at a higher speed

Although clutch wear is minimized, synchromesh wear still exists. This may not be an issue because the synchromesh only needs to match the speed of the drive shaft (lots of momentum) to the speed of the layshaft without the engine engaged. The layshaft has a relatively low mass, therefore it is easy to match its speed to that of the driveshaft.

Double Clutching

1 higher gear is engaged, engine and layshaft are turning slow to match the higher gear

2 clutch is disengaged, layshaft turns independent to the engine

3 neutral is selected, driveshaft and layshaft are now independent

4 clutch is engaged, engine and layshaft are connected

5 blip gas, BOTH engine and layshaft speed up

6 disengage clutch, layshaft is independent to engine

7 shift to lower gear, layshaft is already turning at a higher speed to match the lower gear, NO SYNCHROMESH ACTION!

8 reengage clutch, engine is already at a higher speed, no clutch action


For those not already familiar with the basic layout of transmission guts, this may help. Ignore the "dog ring" stuff since unless your NSX is a racecar (maybe not even then) you don't have that. Also, this may be obvious, but the driveshaft spins the flywheel which would be sandwitched to the other side of the clutch.

typicalgearbox.jpg


Full article w/video explanation of synchro function:
http://www.carbibles.com/transmission_bible.html

Disclaimer: This only approximate the basic function of a generic transmission and all items may or may not be applicable to the NSX.


Explanation of double-clutching taken from HERE


::EDIT:: nice find NSX-2004/074
 
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One version of the alleged "TSB" is in post #6 of this thread: http://www.nsxprime.com/forums/showthread.php?t=74757

In my opinion, it looks more like an article from a monthly Service Department newsletter or some such.

As far as my $0.02 on the subject here...if we all should be so worried about synchro damage when skipping gears because we are driving lazily...what the heck kind of damage are we doing when we are driving hard??? I can't imagine that either shifting method, in moderation, is going to cause excessive damage to any transmission, let alone a sports car transmission.

Ah! Nice! Well thats not a TSB!!! Thats one of those little "helpful info" articles. I would suspect there is a similar article somewhere about not approaching the redline. This one is starting to seem like one where common sense should just prevail. Understanding a bit about how a manual trans works, I think it isnt too hard to figure out if a certain behavior is going to be brutal on the synchros.

My fear was that there was something specifically wrong/different with the Honda/Acura trans that warranted them actually stepping out from the norm.

This article is more along the lines of "Dont forget to change your oil!"
 
If you want to maximize MPG, then perhaps maintaining a low target RPM range is desired.

but also keep in mind, the more you shift, the more wear and tear you will put on your trani and clutch.

Shift low when cold
 
Note the FAQ:

1. Can you go from 2nd/3rd/4th/5th gear and straight into neutral or do you have to go through them all? Can I go from 5th to 2nd/1st?

Yes it is recommended that in a modern manual transmission you can skip gears when going up or down. For example; when accelerating you can if required change-up from 1st to 3rd, though 3rd gear may labour due to low engine revs.

This info has to be deleted in the FAQ. :wink: There have been several discussions of people including me who avoid skip-shifting.
 
dont skip going up, dont be lazy. rev match when going down gears, at least from 6th or 5th to fourth, dont take it out of gear rolling at 65mph. Its not hard rev matching. push clutch in, rev it and down shift. People do it all the time racing in those hard core videos from japan. They know how to drive the nsx, hardcore upshifting and down shifting......Japan races the hell out of the car, they designed it to do just that. If the gt wing was more appealing to everyone, car probably whould have had a gt wing and been lowered more too. Come on, its basically a race car. The only harm to this cars gears can be shifting like a granny at 2k every gear.
 
...The only harm to this cars gears can be shifting like a granny at 2k every gear.

You've to explain that. My grandma didn't have a driving license but I'm pretty sure she's wondering herself like me why shifting at 2k every gear will harm the gears. :confused:
 
I think I got this link from another prime member, but anyway it shows double clutching in a great way, and in an NSX. I never tire of watching this, I love the multi window filming.

http://video.google.com/videoplay?docid=7014510364856677447&q=nsx&hl=en#

I've seen that video several times and what he is doing is single-clutch heel & toe on the downshift and single clutch on the upshift. Unless I missed something, he does not actually double-clutch anywhere in that video. Would you mind to post an approximate time stamp for when there is a double clutch?

This video, on the other hand...
http://www.youtube.com/watch?v=0j-3xIZK-Bk
 
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I should've included the fine print in my last post where I claim no responsibility for any hours of your life wasted on youtube, etc. etc. :).

That was pretty good, he got the part about double-clutching correct. The key is that your throttle blip has to come while the stick is in the neutral position and the clutch is out.

One important thing to ignore though: with our cars (early 5-speeds in particular) you can forget about "shift as fast as you can", since that can result in afore-mentioned "money shift".

The best method is to be gentle and positive with the stick. It is self centering, so use that to help you find gears. I have a feeling most folks that are trying to go from 5th to 4th and end up in second probably had a whole handful of shifter and were trying to yank it down a gear in a moment of adrenaline. Been there, done that in my MR2, thank goodness it just locked the rear wheels and didn't find a weak point before that.

It's better to relax and use your wrist, or even your just your fingers to move the stick around vs. using your whole arm. The level of precision is just that much better. Think of it as writing. Your letters didn't come out well when you were 5 and moving the crayon around with your whole arm did they? You're grown now and using a nice ball-point pen. A little flick of wrist, allowing the spring-action to work with you is all you need.
 
What type of damage can be caused to the engine from high revs when the engine is cold?

Engine oil needs to rise to a certain temperature to reach ideal viscosity and provide adequate lubrication. The most damage to an engine is caused within the first few minutes of operation.

It's also important to remember that even if your temp indicator says "OK", that's coolant temperature and your oil will take just a bit longer to reach optimal temp.
 
The best method is to be gentle and positive with the stick. It is self centering, so use that to help you find gears. I have a feeling most folks that are trying to go from 5th to 4th and end up in second probably had a whole handful of shifter and were trying to yank it down a gear in a moment of adrenaline. Been there, done that in my MR2, thank goodness it just locked the rear wheels and didn't find a weak point before that.

+1. The Borg Warner T5s in the 280ZX turbos and foxbody Mustangs are famous for stripping 3rd gear for this very reason. Overzealous shifting.
In the NSX, with the reverse gear refusing to engage, all you really need to do is pull back, the stick centers, and you end up in 4th.

The NSX, more or less, feels like you have to "ask" for the gear. You wait at the gate, and a split second later she goes in. Very gentle.

BTW, Richard, you ought to see this beast run ;)
 
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