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.

You did! I still need to look into doing something like this

Sent from my SM-G955U using Tapatalk

With the twin, I suggest you start by finding that sweet spot between 1st and 2nd at low speeds. At first I noticed a slight "gear meshing feel" if I didn't have it just right. Then I would speed up (or slow down) the shift speed until I felt it slip into 2nd with no feeling at all.


Now, if I could just remember not to try to take off at stop lights in 3rd gear … :bonk:


humfrz

Hahaha I can't imagine trying to "throttle dance" with the clutch to start above 1st gear like I would in the big rig.

Now my experience with trucks is that EVERYTHING relies on RPMs. You have to rev match every and anything or it's just not happening. Miss a gear, rev match; downshift, rev match etc or you're gonna be hanging out in neutral all day.

So when you say low speeds, are you meaning specifically shift to 2nd way early (like almost right after you've fully engaged 1st)? Do you mean eco-driving and refraining from redlining every gear? ;D

I've tried playing around with shift points (all rpm based) to no avail. I admit my timing is off as others have mentioned in this thread and learn quite a bit from recommendations.

P.s. to OP: sorry that your car is behaving wonky and these continued replies don't necessarily remedy your situation.

Sent from my SM-G955U using Tapatalk

Yes, slow speeds, like gently moving through your neighborhood.

That way, if you miss it, you don't have people yelling out "grind me off a pound", or if you mess up, it won't destroy the transmission. - :)

When I was driving large trucks, back-in-the-day, my biggest screwups came when I couldn't remember which side of the axle (2 speed differential) I was in. - :confused0068:


humfrz

Hahaha I'll have to do more experimenting when the neighbors aren't home. I appreciate the tips!



Sent from my SM-G955U using Tapatalk

To be honest, I have tried clutchless shifting 1st - 2nd for a few times but the transmission didn't allow my gear stick to move from 1st to neutral. There were some kind of force to hold it to 1st. I am gutless to yank it out of 1st fear of ruining my feeble transmission.:iono:

The hub sleeve which slips between gears - first and second in this case - has a shape which matches up with the dog teeth on the gears. The angle is such that whenever there's torque in either direction, the sleeve gets sucked into the gear. That's the force you're fighting.


https://dingle.ls2.com/Pics/T56/IMG_6175_Medium.JPG

Well, if your car doesn't want to easily come out of 1st without using the clutch, don't force it.

Oh yes, I don't believe that this transmission if "feeble" nor "made out of glass" as long as one doesn't try to put more power through it than it was designed to handle and one doesn't "beat on it".

If I, and some others, can consistently and smoothly shift up through the gears with this transmission without using the clutch - most people should be able to do that while using the clutch - :sigh:

Timing is everything. - ;)


humfrz

It really is.

As Ultramaroon said, the sleeves lock to the gear when there is load. You can’t easily pull the sleeve into neutral unless there is zero load. Load doesn’t have to be positive either. If you are decelerating it will apply negative load.

I wouldn't recommend clutchless shifting as a matter of habit. If you're intent on doing it and you can't get the tranny out of first on overrun try preloading the shifter and easing off the accelerator. It should drop out of first as soon as the transmission is unloaded. The move out of a gear is similar to clutchless shifting a constant mesh sequential gearbox (e.g. motorcycle). The key is unloading it.

As to getting from 1 - 2 smoothly at low speed, I've had the best luck moving the shifter quickly, but with minimal force. For reasons I can't explain the first-second sychronizer likes lots of foreplay at low speed. Move the shifter out of first quickly and then gently apply pressure to get it to slip into second. You'll feel resistance going into second, patience is your friend.

Well, 1st & 2nd synchros ARE different to rest, IIRC triple cone (for lasting longer with with higher torque due gearing at these gears? Or due gearing ratio differences of first gears and thus more rpm difference to even out?) vs single cone synchros for other gears. But then again many cars have such combination, and for many other cars there is little if any difference in engaging first gears, so i guess that's not an excuse.

Go to the home page of member PandaSPUR and read his method in his post of May 18, 2017. It worked for me right away. All I had to do was step on the throttle a bit sooner when shifting to second. I too drove trucks and I have a hard time not 'bumping" an imaginary governor sometimes. When I started driving trucks the operating range was mostly 1600 to 2100. Then on the Maxidyne 5 speeds that came out in Nov. of '66 it was 1200 to 2100. The last truck I drove it was 1200 to 1800. Time marches on but we sometimes have trouble getting rid of old patterns in our heads. Good luck!

This one?

Concentrated today on being a bit more deliberate with the shifter and seemed to have a better time of it.

Still think it's odd it only happens at low speeds, but eh. Satisfying transmission to work nonetheless.

Yep:thumbup: