RPM jump when upshifting

Drex

it doesn't match on upshifts but it does hold the revs from dropping too low if you're slow to shift

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2011 Nissan 370z | 6MT | Magnetic Black | Sport Package

Spikuh

Incorrect. Simply get in the car, turn on SRM, start driving and rev to 4k, shift from 1 to 2 and don't release the clutch. You will notice the RPM's do NOT drop back to idle. They hold considerably higher somewhere near 3k.

That is rev matching.

Now do the same thing except with SRM off. Notice how the RPM's drop back to idle.

That is NOT rev matching.

Also called rev matching....





Rev matching has nothing to do with downshifting or upshifting, but is simply about matching the engine rotation with the rest of the drivetrain. It just does not happen as much on the upshift because if done properly, you can basically "catch" the engine as it slows down. Done properly will allow for a smooth shift, done less than properly will provide a rougher shift.

roy'sz

[QUOTE=Spikuh;1619759]Incorrect. Simply get in the car, turn on SRM, start driving and rev to 4k, shift from 1 to 2 and don't release the clutch. You will notice the RPM's do NOT drop back to idle. They hold considerably higher somewhere near 3k.

That is rev matching.

most of the people on this forum would agree that what you have just stated is incredibly false. When you drive do you hold the clutch down and wait for the speed to match the gearing in your car for the correct shift? I didn't think so. It doesn't work with up shifting. If you read the owners manual and understand that the purpose of srm is for the lazy way of "heel to toe" the brake and gas when downshifting and matching rev's with gears while DOWNSHIFTING, not upshifting.

Spikuh

For the bolded part. It is a very oversimplified example, which I probably should have stated. Of course there is more going on with an upshift, but unless you want to wear out your clutch super fast, letting the RPM's drop some between upshifts is a good idea.

For the rest of what you said, I am going to have to back up to your first quote and restart there.

You said:

The part where you say SRM does not match upshift is categorically wrong. It says so in the manual:



SRM does not think, "Is he downshifting or upshifting?" It thinks, "Is he shifting?". Look at it this way. If you are upshifting from 1st to 2nd going from 4k RPM's to 3k RPM's, then SRM is going to hold the throttle at 3k RPM's while the clutch remains engaged. Similarly, if you are downshifting from 3rd into 2nd from 2k RPM's to 3k RPM's, SRM is once again going to hold the revs at 3k RPM's while the clutch is engaged.

Her is a youtube video of it in action on both upshift and downshift. Start at the 50 second mark if you want to skip his little intro. No idea who this, I just did a quick search.



So TLDR:

-I should have given a more thorough example.
-SynchroRev Match does work on upshifts.

As for whether or not SRM is the lazy man's heel-toe? This is irrelevant to the point you made in your first quote and is therfore...still irrelevant. As to the purpose of SRM, that is also irrelevant to the point you made as we are talking about how and not purpose.

hadokenuh

So can you someone answer the question I've been trying to get an answer:

With SRM on, when I upshift not from stop but from 1-2, 2-3, 3-4 etc., is it ok to let the clutch out immediately after shifting? Does that damage anything?

I've been doing that and have not seen/heard anything weird. And yes, I read the manual which says the SRM helps upshifts as well.

roplusbee

Looks like some people have either gotten used to SRM or drive with it off. I guess I was dumb for reading the booklets that came with the car, lol. I normally turn SRM off for normal driving and turn it on when I want to be spirited (not always though).

OP......you will get used to it. She can be kinda finicky sometimes!

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roy'sz

no it does not, he doesn't know how srm really works. You are fine, srm will hold the revs when upshifting but you have to wait a couple of sec to shift into another gear. It is somewhat normal to get blips on a quicker upshift because the ecu doesn't now know what it is that you are planning to do when you are on and off the throttle. IN conclusion change your timing with your foot work on clutch and throttle and you should notice the changes in shifting.

roy'sz

New370Z 3.SynchroRev Match - YouTube


like i stated before spikuh, it is a "lazy" way of heel to toe. here is the demo video that supports my statement before. Enjoy!

Spikuh

Trollololo. Glad to see you agree with me now.

Like I said before, you are making an irrelevant point, which I am not saying is wrong, just that it has nothing to do with anything... Go read what you first wrote...

Do you have any idea what you are saying at this point or are you just digging in?

Spikuh

So long as you are not beating on the car, I doubt you are doing any amount of meaningful damage. For normal daily driving, I find I can let the clutch out in a fairly normal manner immediately after the I change gears. However, I do not force a gear change and I do not dump the clutch, it is all very controlled and "effortless" for lack of a better word. I will try to describe it a bit better.

Whenever I am instructing someone new to a manual car, I tell them that they should be able to shift the car with either the palm of their hand gently resting on the shift knob or with two fingers. That gets them familiar with how the transmission likes to work and the speed at which it likes to shift.

For clutch control, the whole idea is smoothness so I start out telling them to get a feel for the engagement point and work on learning that point. It will be rough starting out as the motion gets commited to muscle memory, but after a couple days it should get pretty second nature. From there it is just a matter of refining the process and learning what to do and not to do with the clutch.

So long as you can make the whole process smooth, wear and tear should be fairly minimal, but ultimately it boils down to practice and learning the car.

hadokenuh

Thank both of you (Spikuh and Roy) for answering my question.

Besides the exciting tech talk

roy'sz

your welcome