masterdk

Just a little background, I got a new 2016 Z51 3LT Stringray 7 speed late last year. On day 1 of delivery, after ~50 miles, the car broke down. The transmission "broke"

After ~5hrs of waiting, I finally got GM to tow it down to the dealership. 2 weeks later, they fixed it. It was missing some pin locks from factory... I have a few concerns with the car, and I'm wondering if this is normal as the dealership claimed.


1) On cold start, the transmission gear grinds, or is very jumpy going into 2nd gear. Sometimes it would just come back out of 2nd, or the 2nd gear indicator would not come on. Clutch is all the way in. This happens without letting go of the clutch. My only resolution is to shift very very slow in the morning, or double clutch. When i complained, they gave an article saying its normal for the manual transmission when its cold.. I don't recall having this problem when i first drove it, but i didn't have it for long. The issue isn't as severe as it was initially, but it's still there. Is this normal?


2) My second concern, my temperature stats for my transmission are always below 100. I drive 15-30min sessions. I was thinking this was diff temp, but the other screen says "trans". Any insights? Is this normal? I attached a picture of it.

ersatz928

1) I think your temperature sensor, on the transmission case, was not plugged back in (the electrical connector) when the transmission was serviced....that would make it always read at the lowest scale, 100F. This sensor is on the drivers side of the trans case, near the bottom, and also serves as the drain-plug for the gear-oil.

2) What exactly "broke"? Can you describe the symptoms?

3) A slight grind when going into 2nd gear is a somewhat common complaint on the M7. GM says it might do this when the gear oil is cold, and many transmissions have some issues with 2nd gear engagement when cold (like the GM memo describes), but some of us (me included) still get a 1st-to-2nd grind when the transmission is hot, which is not "normal", it is due to a problem with the 2nd gear synchro. GM and Tremec are aware of this synchro problem, but don't have a fix to offer, short of replacing the transmission and hoping the new one doesn't have this issue.

https://www.corvetteforum.com/forums...-2nd-gear.html

https://www.corvetteforum.com/forums...ift-17-gs.html

https://www.corvetteforum.com/forums...placement.html

brooklync5

My 2014 m7 is very notchy when cold and going into second. Normally smooths out after the first few gear changes which is completely normal. Jumping out of gear or grinding is NOT normal and never happened to me. Maybe a bad synchro but I would definitely have the dealer address it. As for the temp seams like the sensor is either not working or disconnected.

monicatomokc

Ditto. It was in the upper 30's today going to work and could definitely notice the second gear 'crunch," but it did lessen at the end of my 12 mile drive. Looking forward to those 80 degree days (not the upper 90's/100's though) and less crunching!

The only thing I would add is I have experienced the occasional pop out of second gear, but attribute it to my fault for not making sure it reached the stop point. Paying more attention now and it hasn't happened in a long time.

masterdk

2) What exactly "broke"? Can you describe the symptoms?
-The shifter seemed to have disconnected from the transmission. The car was stuck in 4th gear, and there was no feedback from shifter. The clutch still did work. They said there was locking a "pin" missing from factory.

ersatz928

Did they replace the whole transmission, or did they repair it?

Bill Dearborn

Nibbling going into 2nd gear when cold is standard fare for Tremec transmissions of this type which are used by other companies than GM. My two C5s and C6Z did it as well although the nibbling disappeared within a mile of starting to drive even in very cold weather.

Bill

masterdk

Finally grabbed the paper, it looks like they repaired the transmission instead of replace it. "Shift rod roll pin not installed from factory.... Shift rod disconnected.. R N R Shifter and transmission, and torque tube assembly replaced shift rod. After repair vehicle shifts no problem."

I'm not sure how much disassembly & reassembly this is. Did this mean they had to take apart the shifter assembly in the car on top (possible mis-alignment upon reinstall?), and take apart the transmission below? Do they normally bleed or do anything to the clutch?

masterdk

Also, the article they gave me about transmission problem was #03-07-29-004k: Manual transmission operating characteristics - (Apr 7, 2016). A copy of this can be found on the first link on google.. They specifically highlighted the "Cold Operation" part of article.

raylo

My slight grind going into 2nd is getting better after 4k miles. I guess it is breaking in. But I still don't attempt fast shifts until well warmed up.

dbirdhouse1

I also have had the first to second "grind", so I have the tranny temp gauge on display and it takes about 20 minutes before the temp changes and the grinding stops, fairly typical (as others have said).....

masterdk

Funny.. I called dealer and he told corvettes don't have temperature stats for the transmission. If i need to want someone to look at it I have to schedule an appointment. I asked about car loaners, and they say they don't give any out..That's a pretty big downgrade from my Infiniti services. Anyhow now i have to figure out logistics on how to get the car dropped off.

Question for everyone, what ball park temperature your getting for your transmission in the display? Is it usually hoovering the 150-200 mark?

HurstSRT

My Challenger SRT had a Tremec 6 speed ( also used in the Viper ) and it did the 2nd gear nibble. Was told by Dodge that it is normal. The colder it was, the worse it got.

AORoads

I first ran into a balky shifting issue in a new '82 sports car in sub-zero temps. The dealer said to paraphrase: "It happens, be careful, double clutch or skip 2nd until trans oil is fully warmed up (trans oil, not car coolant) or you'll wear out synchro. And, no, the car and trans mfr. were not seeking out a solution."

My suggestion to others on here is to do what OP has tried (but doesn't prevent trans from jumping out of gear---which means the trans is not fixed and may have other issues): double clutch. Or shift very gently, or skip gears (1-3) until trans is warm. For those who will keep their cars longer than the B2B 36 month warranty period, it will save a trip to the dealer, a warranty claim and a "fixed trans" like the OP now has. Which is not fixed, obviously. Good luck, mastedk.

falconhulk

5hrs? You should have just called the roadside assistance number. They would have had you back in an hour.

falconhulk

huh? Did he mean there are no temperature readings for it in the DIC? Did you tell him there was? It depends on the dealership for loaners. Tell them you are going somewhere else because of their loaner policy.

masterdk

It was 1hr waiting for dealer tower, and when that failed, that was another 4hr waiting for the gm roadside assistance. They seemed to have coordination problem getting the "right" tow truck. When time came, 2 different towers dropped in at same time.

I told him the transmission temp in the DIC was stuck at 0. He told me they don't don't have temperature sensors.

What kind of temperatures are you guys getting on that same screen i have in the original post?

Dunga

Hi! I have a 2014. I remember the 1 to 2 shift being clunky, with some grinding when the temps were cold. I've had it pop out of gear a few times, <10 total in the first year.

Now nearly 3 years and 17K miles later, I can say it hasn't popped out for a year and a half. The 1 to 2 shift either got better, or I got better at it, or both. Significantly less noticeable even in the Minnesota winter.

ersatz928

Some people have the 1st-to-2nd gear grind even when the transmission is hot....

cheapthrills

Just took my typical drive to the gym. Never look st the tranny before but I did today. After 20 min drive in 83f temps it just started budging above 100f.