6th-5th grind due to transmission or noob shifting technique?
 

I've had my car for 2 years now and I've only just noticed this grind when I'm shifting from 6 to 5 when i'm over 3k RPM. Tbh, I may have had this grind since day one, I have been driving conservatively slow on the freeway until recently.

When I downshift from 5-4,4-3, or 3-2, I clutch in first then shift and rev at the same time. I have no issues with those gears. However if I apply the same technique to 6-5 it will grind. The sound is worrisome :/ This occurs over 3000 rpm mostly. On the streets it won't have that issue but then I'm never in 6th and over 3000rpm on the streets.

My only method to avoid the grind so far is to clutch in, rev, THEN shift to 5th. As long as I don't shift and rev at the same time it'll be alright. When I started doing this, I began to wonder if I'm just shifting shitty or if there's an issue with the transmission (which I've seen reports of).

Yeah. I have that issue as well. My transmission grinds specifically from 4th to 5th or rev matching from 6th to 5th. Doesn't matter what RPM I'm at, it just grinds if I don't slowly clutch in, shift up/ down, and release clutch while adding gas. It has happened since the day I started driving aggressively (shifting pretty fast) about a year ago. I've just learned to shift conservatively and slowly whenever shifting down or up into 5th. For reference, I currently have the KartBoy Shorter Shifter with transmission bushing, the MTEC Shifting Springs, and a way heavier shift knob installed. Even prior to the grinds, it was pretty prevalent too.

Damn that sucks guys, I don't have this issue but if I did I would be pissed off as hell. Maybe new transmission fluid is in order? I'm running Motul and I don't have any of the issues your describing.

I have to ask some of these questions to everyone who has transmission problems.
1. Is this your first manual trasmission car? how many years/miles/cars experience?
2. What is your experience with performance oriented manual transmission driving at high rpm? rev matching, etc? what is your fastest shift? what is your slowest?
3. When was the last time you changed gearbox/diff fluid? at how many miles? What did you use?
4. What mods do you have? Shifter, Knob, Bushings, Springs, Adjustment, Spring removal, etc

I switched to Amsoil fluid at 5k (20k now). Just got back from a 60 mile drive and I couldn't reproduce my grind at all. I did drive another 60 miles earlier in the day. So maybe time for new fluid? I have some Motul 300 sitting in the garage already but I didn't want to put it in if I was going to bring it to the dealership who might drain it out. Perhaps the Amsoil just needed some warming up?

I usually jsut drive 40 miles in the morning and then again at night for work. Today was a rare day where I would drive over the 40 miles. How long does it usually take for the transmission oil to warm up?


I've been driving manual for four years and I've never had a seasoned manual driver critique my driving so hard to day what my skill level is.

It could be anything really.
Any shifting mods?
It could be the syncros aren't as good in the higher gears as they are in the lower gears.

Do you rev match every down shift? Or at least at mid to high rpm?
Which fluid did you use? is it gl4 or gl5 rated? weight?
It takes about 10 minutes to warm up the transmission.

I see like you only have the problem going in and out of 5th.

no mods. i'm using Amsoil 75w90 GL4. Always rev match on down shifts, do some people just down shift and let the engine and drivetrain catch up? :/

I'm sure many do; it's a bad habit to use the clutch to spool up the engine. Always revmatch.

As I understand it, as soon as you clutch in the engine and gearbox are disconnected and they no longer influence one another. So when you say revving before shifting eliminates the grind doesn't really make sense. Is it grinding as you are moving the stick into gear, or when you're releasing the clutch?

The only way the transmission can grind (unless something is malfunctioning) is if you are letting the clutch out before you are fully engaged in a gear. The 5-6 or 6-5 shift seems to be a problematic for many on this forum. However, there are also alot of novice manual drivers here as well who love complaining. So it's difficult to say whether there really is an issue with those gears, or it just requires a little extra finesse that many lack.

You've been driving this car for 2 years; you're certainly no novice. But if you suspect this grind may have been present since day one, then you can't rule out driver error. It's easy to develop bad habits. Shifting quickly at high RPMs is difficult and requires practice. So before you can say for sure it's a syncho issue just be absolutely sure the shifter slides into gear completely, BEFORE you begin to release the clutch.

It's the trans...I had the same issue and Toyota replaced like under warranty.

Same issue just started for me. No mods to tranny (had weighed shift knob for a bit, but stock right now) 6th to fifth grinds unless i double clutch. it grinds when I'm pushing the lever into 5th. It also doesn't grind if I clutch in -> move lever to between 6th to 5th -> rev match there -> SLOWLY put it in 5th. which takes forever.

Going to have dealership look at it.

I'm reading everybody's shift technique and starting to question my own. I have always thrown my car into neutral and let off the clutch to rev match before stepping on the clutch and downshifting. Am I doing it wrong? Is this what Vin diesel refers to as granny shifting?

That's a proper double declutch. Shouldn't have to do it with a synchromesh box, but Subaru gearboxes are "special".

@tracerit, my hunch is that your rev matching is off by a few hundred RPM during your down change, which I've found this transmission to be very sensitive to. Try concentrating on matching revs more precisely and see if it eliminates the issue your experiencing, or double clutch during down changes. If you don't have experience double clutching, do some research - as alluded to by @kounkun, there a proper technique that needs to be mastered.

the grinding occurs during the actual shifting from 6th to 5th, all while the clutch is fully in. Tonight I drove the car after having not used it the entire day and couldn't reproduce my grind, was downshifting 6-5 again and again for a good 3 miles on the freeway.

Thinking about it now, I mainly notice this problem on my way home from work in the morning. I work graveyards and although I park in a parking structure, it is exposed to the weather somewhat.