XdoubleDot

Looking for some guidance on a shifting issue I'm having. Car is a 2014 Z51 M7 with 23,000 miles (10k by me) that I've owned since 2019.

The issue is that it is very inconsistent in shift feel. Sometimes it slides into gear great (bolt action rifle feel), other times it's a bit "crunchy" and seems to take a lot of force (oe shift and mgw shifters tested). Certain gears are better than others, 2,3,5 and 7 have the highest likelihood of a bad shift, however first takes way more force than expected if rolling at ~1mph for a car with triple syncros.
Rev matching (not the ARM), but actually revving it with the clutch out in neutral before the next gear is selected does typically help, although it isn't always needed for a good shift, sometimes it's great without it. I get "crunchy shifts" shifting fast or slow, but it's more often it's with higher rpm/faster shifts where the syncros are being asked to do more.

Things I've done

1. 2x Ranger method clutch fluid changes the last 2 years. Do I need to bleed it at the T/O bearing or is this good enough?
2. Switched to redline atf-4 at 16,500 miles in 2020 as I heard it would help with cold weather shifts. Didn't note a huge difference. Plan is to double check the oil level
3. Tested that the clutch disengages all the way. Put car in 1st on flat ground, rev'd engine with clutch on the floor, no movement. Clutch doesn't start to grab until ~1/2 way up the pedal so it doesn't appear to be a dragging clutch issue, although this is what it feels like to me based on previous experience).
4. Lastly I put a MGW shifter in about 500 miles ago. Everyone typically raves about how awesome these are, but I found it exacerbated the issues I was seeing with the oe shifter (it looks great, but makes me hate driving the car more (anyone want an MGW shifter lol)). I did the copper washer spacer on the shifter detent as well as redid the alignment with the provided tool, all to no avail.

I have 2 other manual cars that all shift better than this, and both have over 200k miles. It's rather frustrating driving this car as you never no what the next shift might feel like. Are there any common linkage issues at the transmission I need to check? can the dual mass flywheel cause issues?

thanks for the help!

Scruff Vette

This M7 (Tremec TR-6070) shifts best for me when I handle it gently using my fingertips for 2-4-6 and heel of my hand for 1-3-5-7 to guide the shifter through the gates working with the centering spring. Slow or fast it doesn't matter, shifts are every bit as slick as any manual trans I've driven. If I grab the **** and yank, push/pull into gear it is not anywhere near as smooth and can occasionally feel the gear nibble as they mesh. Smoothness is key.

XdoubleDot

I appreciate the input. something isn't right with mine, I'm looking for potential causes as to why it doesn't shift like everyone else's transmission

Bill Dearborn

All the Tremecs used in Vettes since 1997 that I have driven (2 C5s, 1 C6, 1 C7) require more effort to push the shifter into low gear. Shift technique can definitely be an issue with these transmissions and cause the problems you have noticed. From an operator standpoint, the only other thing I can think of is the timing of clutch operation with shifter movement maybe there is sufficient difference between the two other cars that you have and the C7 that you are off on the timing of the clutch in and out.

There could be a latent factory defect the POs never had repaired while the car was under warranty or a wear issue in your transmission but most people don't experience any real wear issues with only 23K miles on the clock unless the car was abused by a PO and my experience is they can take a hell of a lot of abuse.

Bill

XdoubleDot

good to know on first gear. I had read 1st and 2nd had triple syncros, so I kind of assumed it would handle a 1mph roll (input shaft at idle rpm) really well. That aspect of the shifting doesn't really bother me as it's few and far between.

Has anyone seen issues with the shifter linkage being out of adjustment? or something loose?

I'll admit the electronic throttle doesn't help with the shift timing, but i'm rather familiar with how to unload the trans. I think i'm making it as easy as possible on the syncro's and i'm still getting the crunchy shifts from time to time on the gears mentioned above. I watch other people (normally after installing an MGW, which I also have) easily rowing through the gears.

Avanti

If the fluid level is okay, drive the thing. If it will make you feel better, change the fluid. Don't pretend it's a race car and treat it like one; it's not despite GM hype. If something is going to need work at some point you'll find out. There's no easy way to do anything now.

I should add that this implies that shifter alignment/functioning has not been mucked-up anywhere along the way.

Adir Hassid

I totally feel you, I dont think its just your car in particular but just a corvette thing.

Yes the MGW just exaggerated the transmissions faults.... something i was kinda bumbed out when i installed.

My car only goes into second when it feels like it, when its "cold".

Ive realized the vetted rewards slower shifts in order to shift fast... sounds weird but i swear anytime i try to do it quicky its misses a gear.

Also once the tranny is completely warmed up it feels much more refined. It a piece of crap when its cold.

ersatz928

Yes the Tremec synchronizer design in this TR-6070 transmission is a bit iffy, especially for 2nd gear. They are typically a little stiff when cold (like almost all manual transmissions), most are fine when the transmission gear oil is warm, but some, like mine, often give a 2nd-gear engagement crunch even when warm. I suspect that I (and sounds like you) got an off-tolerance 2nd gear synchro from the factory.

I have tried Mobil-1 Synthetic Dexron-3 fluid, no improvement, and just yesterday I changed to Redline D4 Dexron-3, which seems no different than the Mobil-1 or factory fill fluid.

My 6-speed Tremec T56 in my 2001 C5 Corvette never had a hot 2nd-gear synchro crunch, in 80,000 miles of driving. My C7 7-speed did this when new.

And yes, the MGW shifter, or shift rod alignment, or clutch fluid, has nothing to do with the inconsistent performance of the Tremec gear synchronizers.

CraigStu

I would give the shifter adjustment a try. I have the bulletin but it is saved as a pdf document so I can't post it here. I could email it to you if you can't find it. email me at craigstuard@comcast.net and put Stingray as subject so I don't delete it.

C7&7

I have had 2 manual C7s and 1 manual c6... they all are very notchy in low gears when the tranny isn't warm. It's normal.

76-Vetteman

A 2014 Z51 M7 driver here. My experience is the same as yours. And it has taken me at least 3K miles to learn how to shift the gears efficiently.

I thought driving the M7 would be easy because I've owned a C4 and a C5 Z06, both with manual transmissions, and a few hundred thousand miles driving with manuals' over time. That was an error on my part.

There could be another variable. The dual disk clutch may play a role here too. After moving the seat a little further forward, disengaging the clutch pack a little deeper, I found the transmission shifts smoother. I've wondered for a while if the dual clutch assembly could cause part of the shifting difficulty.

Scruff Vette points out some good stuff here. Smooth, positive lever action through the gates is a major key to success. And as mentioned above, moving the seat a little further forward have helped me too.

In the end, This old dog had to learn new shifts.

^&right

My experience is similar, but not as bad as yours OP. More than once I thought I had it in 1st only to pull away from a light and it pop out of gear. The biggest gain for me was not using rev match. That seemed to amplify the issue. Turned off the shifts smoothed out noticeably.

XdoubleDot

I wanted to post a follow up. I've been doing a bunch of work with HPtuners and have made significant improvements to the shifting characteristics. One of the largest came from the rate limit tables. They had all been maxed out, which I believe caused the throttle and timing to be unpredictable which certainly does not help with shift timing. Returning these to stock and then making smaller 25-50% increases (instead of maxing them out) changes has helped considerably. Hopefully this helps anyone in the future who runs across this thread.

CraigStu

This post brings up something I had not thought about. I put one of the extra thick clutch pedal pads on my 19 Stingray a few months after I bought it. As mentioned I have done the fluid and the TSB adjustment and mine shifts fine. This may not be the exact one I have but it is similar.
C7 Corvette Stingray/Z06/Grand Sport 2014+ EZ Clutch Pedal Extension | Modern Gen Auto

C7 Apex

It took me a little bit to get used to mine, I ended up doing the MGW and going to redline fluid and it is pretty sweet. Learning to make sure you are all the way in first gear is a little bit of an art, but I mastered it quickly and haven't had a kick out or grind in months. In the end the trans is super beefy and that means all the parts are big and heavy. Without some sort of power assist, there is some physics you aren't going to get around. I came from a ND miata, which had the slickest shifting manual I have ever had (and I have had a lot), BUT that trans was borderline too weak for a 155 hp engine. I've heard our trans can handle 800+ hp in stock form. Having driven mine (C7 GS) on a road course, I have to say it is awesome. That said, it is pretty physical to shift, and since the rest of the controls in the car are so supple, the required shifting force seems kinda out of place. It took my wife a longer than normal while to get it, and she is pretty experienced.

Internets_Ninja

Having owned multiple C5, C6 and C7 Corvettes, all with Manual Transmissions for the past 20 years, I have learned a few things.

#1) Synthetic "magic" transmission fluids actually make the shifting worse vs brand new OEM fluid which is plenty adequate and has the right friction level for the synchronizers and blocker rings. These parts require a certain amount of friction to work the most efficiently. Many people report better shifting after switching to high dollar non OEM fluid, but it is a placebo effect or their old fluid was low or worn. In the latter case, any new fluid will feel better. But what happens is after the new aftermarket expensive fluid starts to break in over the next few months, the transmission actually shifts WORSE.
#2) The Manual transmission will feel crunchy, especially when cold
#3) The Manual transmission will also fee crunch if you try shifting 1st and 2nd at a low RPM, say less than 2000 rpm. These big gears just feel better when you shift higher up around 3000 rpm. It is not great for fuel mileage, but try shifting at higher rpm's and you might find the crunch is eliminated. It is just the nature of the beast where you want to be able to hold power and shift at high rpm. The low rpm area suffers.
#4) Skip shift, while mostly hated, eliminates the crunch low rpm low gear feel since you skip 2 and 3 gears. I have skip shift disabled, but will often shift 1 to 3 when cold or when I'm driving slow.
#5) When installing the MGW shifter, If you don't perform the shift linkage alignment properly or fail to use lock tight and torque the linkage bolt properly, you can have a shift alignment issue. The misalignment will have a shifting issue right away. The failure to torque the linkage bolt properly can cause a shift issue to develop down the road.
#6) If the clutch is worn out or the master/slave is failing you can get crunchy shifting as the clutch isn't fully or is just barely disengaging. This is typically less often an issue, but is worth checking. It seems you said you already checked this so hopefully this isn't the problem.

Good luck!

GOLD72

I have never been happy with shifting into 2nd gear on my 2019 Z06 since it was new and now has 20k miles. It does shift smoother when shifted at higher rpms and when thoroughly warmed up. A change to Redline D4 at 10k miles really made little difference over time. I have owned previous Tremec trannies in my 01Z, 06Z and 2011 ZR1 and all had far smoother shifting into 2nd gear in general than this 2019.

mike96ss

It looks like the rear bushing in my stock shifter is done. It's hard to find gears. 2015 with 118k miles. It is time for an MGW, as parts are unavailable to repair the stock shifter. Well, with an extra ~$150. Had one on my C6. I should have gotten one a long time ago.

103FamilyRacing

The Tremec in the C7 is a great tranny but it doesn't like to be rushed. Best thing you can do to give you a better shift is put a tick performance shifter in, the MGW is not bad but I didn't like it at all! The Tick will make it easier and better but no matter what you do these Tremec's don't like to be rushed.