Rougher shift when short shifting?
 

Obviously grinding is never normal in a transmission, but it seems like my 1-2 gearshift got a lot more finnicky after hitting 30K miles recently (im at ~32K atm). Had the car since about 15K miles.

I generally don't wind out 1st gear that much when im just puttering around town, usually into 2nd by 10 mph, but i've noticed that is when i get my rattly/crunchy shifts. If i rev out all the way to 3K or 4K RPM it's smooth 99.9% of the time. I already switched to motul in the transmission and it didn't help this issue. Also replaced fluid in the master cylinder with new stuff.

Is it harder on synchros to "short shift?" Obviously i dont mind doing this but just wondering if i was being harder on the transmission by short shifting first gear.

You can try different tranny oils, many people including myself used Redline, others like Amsoil.

Other than that, my guess is as good as the next person.

Really make sure your foot is off the gas before you depress the clutch. The 1-2 shift is finicky like that. Then make sure the clutch is all the way in, then shift with force. Really slot it into second. Show it who's daddy. Works for me. I shift at about 2500-3000 rpm in a MY17, btw. Not sure what that translates to in a Zenki

should not need to use force..the gates are pretty narrow and going straight from first to second can be pretty easy to miss. Just need a more precise and quicker throw.

Not if you give them time to do their thing - ;)


humfrz

You are both waiting too long in neutral. It's a matter of timing. If you're too slow with the clutch disengaged in neutral, the input side slows down too much. Then you have to use a lot of force on the syncro to spin up all the gears (yes, all the gears) to match second gear speed to the output shaft. It's pretty stubborn when the fluid is cold and thick.


With a tiny bit of pressure on the gearshift, just as the clutch is depressed so that it lets go of first gear as torque is relieved from the shift collar, flick it through neutral towards second gear without pausing. It will literally drop into second as soon as all the gears wind down to the right speed. I drive super gently and try to keep it around 2000 rpm when it's stone cold. Takes no effort to shift even then.


If you miss the opportunity, you can either wrench hard on it, or double clutch to wind it back up in neutral. Your choice.


I double clutch.

If you rev the engine with the clutch in you will notice the RPMs fall rapidly and then slows as the revs drop. All engines do this but the idle control on this car seems inconsistent. It slows the revs as it gets close to idle to prevent it from dipping too low and stalling. Sometimes it just floats at 2k and sometimes it drops very fast back to idle. This makes timing the shifts at low RPMs really finicky.

Long story short it’s a timing thing. Don’t stress out about it too much. Just don’t try to force it. Apply smooth consistent pressure and the syncros will do their thing.

You also say you didn’t have this problem until 30k. I suspect it changed because of software changes like a new tune or something. Early flashes had idle issues which were later fixed. Maybe you went to the dealer and they updated your flash? Or maybe you had the battery disconnected recently? That resets the ECU and when it’s still learning I’ve found throttle input and idle to be really wacky which also complicates things.

What everyone else said. Don't wait in neutral at all, otherwise the revs drop to much. Also don't shift much before 2500 rpm's, the car generally hates being below 2000 rpm's in any gear.

I don't wait much in neutral when shifting. Also the engine has plenty of power to get out of 2nd gear around 10mph. Doesn't lug until you're below 8mph. You really dont need to wind out 1st gear much unless you're having fun, but i can and will if it makes it so i dont grind gears lol. More muscle is not the answer with these transmissions, they're not 70s muscle cars or anything.

It honestly seems random and it's not like a real nasty GRIND, its more of a rattling of the gearshift when i get it into 2nd. Its worse when the drivetrain is cold.

Hi again! I presume what you mean is to maintain that (light) pressure against 2nd and it will fall right in?

Sent from my SM-G955U using Tapatalk

Yes, exactly. Admittedly, 'light' is subjective but I'm confident that once the timing issue is understood, the second-gear flick becomes second nature.


This also translates to all upshifts. It's almost magical in how easy it becomes.

I'd like to expound on this concept.

To understand the "timing" of shifting a MT, I suggest you try this technique.

With the transmission warmed up learn to shift UP the gears WITHOUT using the clutch OR blipping the throttle.

Yes, use the clutch to put it into first gear, after the car gets going, let off the gas and slip the car into second gear (without using the clutch or hitting the throttle). Do the same from 2nd to 3rd and 3rd to 4th.

Once you "learn" the timing, by getting it "right", you should be able to shift up through the gears without feeling (or hearing) the gears mesh, without using the clutch.

After you have mastered this technique, shifting using the clutch is a snap.


humfrz

So I actually drive a 13-Speed big rig for a living and we call this floating gears! I did that for a few years and have been re-teaching myself to use the clutch proficiently for the last year; but for some reason I have the damndest time shifting my BRZ lol..

1st to 2nd is jarring most of the time and I cant figure out if it's my clutch release, or where the sweet spot for the RPMs should be. Granted I'm used to double clutching an un-syncro'd gearbox and I have QUITE a lot more time behind the wheel of my rig. Was afraid to try the clutchless shifting due to unfamiliarity with the gearbox and whatnot though.

Sent from my SM-G955U using Tapatalk

I'll guess that it's your clutch. Have I mentioned this thread? It leads into a DIY.