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For those of us who do a lot of coasting in city conditions....
Am I right to think that with contemporary cars like my Honda Fit or the Yaris you don't have to match the revs when switching from neutral into gear? I was under the impression that the gears were always in synch, as compared to, say, my MT vespa scooter or older MT autos where you had to blip the throttle.
I do a LOT of coasting, but I don't want to damage my transmission.

I'll weigh in - just experience talking, I never had a transmission apart. I drove a standard-trans '86 Caravan, 5-spd for 9 years. Also drove '75 + '76 Datsun + Toyota stick cars and an '86 Mazda 323.

The synchromesh system can ensure the gears are spinning at the right speed re. the driveshaft. The gear you're using of course is spinning at the right speed; the others will be or can be.

So, with clutch down and tranny being driven by the drive wheels, when you start moving the gears around in the tranny using the shifter, they are already spinning at the right speeds and don't collide with the tranny internals when you change gears. I think when you're in neutral they may "coast down" and stop spinning, or at least it seemed that way when I was driving.

Now, when the clutch disk contacts the spinning surface that it bears agains, you ideally want them both spinning at the same speed. That's where your rev-matching comes in. Dig? Because regardless of car speed and spinning internals in the tranny, your engine can be spinning at any speed and you want it to match the tranny's input end.

If they don't match, the tranny will either speed up or the engine will slow down as they get mated together. If you don't pre-match them there's wear on the clutch disk and also lost FE due to the extra friction going on.

I always make it a habit to rev match with a manual transmission. You don't have to do it if your syncros are good, but they will wear over time if you force them to do too much work. Rev matching from neutral or on a down-shift does the work for them, thus keeping your transmission working the way you want it to.

I don't drive old cars anymore,,, so I don't rev match. Ive never torn up a modern MT or AT tranny in anything close to normal use. And the only ones Ive had fail on me were the badly abused ones before I got my hands on them.

My Civic has a rev hang issue. It makes some folks very upset. I love it. Removes about half the work of heal and toe in spirited driving from the equation. So its more about braking setup than the other half.

I don't give the Civic, Accord (AT) or Ranger (MT) a second thought concerning this. I do make it practice to change tranny fluids and filters if used,,,, every third oil change.

psy

I've been driving the wife's Civic AT this week ,while I'm troubleshooting a#3 cyl misfire code on the Insight. There is no driver input needed to rev match the tranny, IMHE (civic). Works very well. If I do a engine on neutral coas, or a FASt, I just drop it back into D and she matches up very nicely. There will be a bit of over rev, 200 rpms or so, but then it finds home and drops back down. I'm trying to keep it under 2k rpm, while accelerating, and have been crusing at 1800 or so. Can't get it (TC) to lock up at less then 30 mph after a dead stop, but after a FAS, if I can keep the speed above 20 mph, she will drop back into lockup at around 1100 rpms.

Got another commute and then I'll have to fill up, kinda been wandering what FE I could get out of her civic.

Randall

Hi Randall:

___I think I can answer that question for you … With you behind the wheel, a lot :D

___Good Luck

___Wayne

In my old m/t cars I would occasionally push the clutch
in and gradually shove the shifter into first while rolling
at a respectable speed, just to hear the synchro bring the
input shaft whining up to some high speed. I wouldn't dare
let the clutch out in that state, of course; just sort of
marveling that the sync rings could actually do that.
.
In actual downshifting, I would always clutch-in, select,
and then blip the throttle just as my clutch foot was
heading back up again, and usually manage to match
perfectly for a zero-lurch downshift. For some reason
this was a lot harder in the Subie than previous cars.
I have no idea what the impact on FE might have been, but
I figured I was at the very least saving the clutch plate..
.
_H*

if your pro enough, lets say your fasing and your speed is like 40 km/h?

bump start (1/2 sec)
engine rev climbs (lets say 1500 rpm) (1/2 sec)
clutch in again shove it into 3rd gear and accelerate (1/4 sec)

bam no need to even rev match ;) what you doing idling in N anyways ;)?

Hi JKandell:

___I always do as mating spinning metal and wear plates at differing RPM’s is not good …

___Good Luck

___Wayne

Thanks for the advice you all. Is it ok if I just let up especially slowly on the clutch as I increase throttle rather than "blip" throttle?

You should avoid that for the sake of your clutch. Quick, clean engagement is what promotes longevity. It gets much easier with practice as you learn to "catch" the engine right as the revs match. Of course, practice does involve doing things a bit more slowly.

Welcome back, btw!