ahesq

Default C7 manual trans gear crunch

I posted this below item years ago, and I thought I would post it again to see if things had changed over 3 model years. Most had replied they had the same problem then, but they just live with it, as I do - for now.

7 speed manual - gear crunch into 2nd and sometimes 3rd
When the car is cold, I experience a small crunch when shifting into 2nd, and sometimes 3rd. If I wait a second before shifting into 2nd, no crunch.

No problem with any other gears.

When hot, no problem at all with 2nd and 3rd.

Any one else have this problem?

pdiddy972

Same - has to warm up to shift 1-2/2-3 smooth. I just got 1-3 until warm.

Steve Carter

It's still alive and well in 2015 M7, 1 to 2 when cold. After three or four minutes it fine. I had the same problem with my 2008 ZO6 but NOT my 2013 ZO6. For some reason my 2013 didn't have this issue. Like you said, "just live with it"

ahesq

Default C7 manual trans gear crunch

I posted this below item years ago, and I thought I would post it again to see if things had changed over 3 model years. Most had replied they had the same problem then, but they just live with it, as do I.

Default 7 speed manual - gear crunch into 2nd and sometimes 3rd
When the car is cold, I experience a small crunch when shifting into 2nd, and sometimes 3rd. If I wait a second before shifting into 2nd, no crunch.

No problem with any other gears.

When hot, no problem at all with 2nd and 3rd.

Any one else have this problem?

Many thanks Tadge.

FYI - I absolutely love my manual 7 speed 2014 C7, regardless of the above. I am 57 years old and I have been a Corvette fan since a kid, to wit - the 1967 Tri power 427 monster.
However, I simply could not indulge in the build quality of GM until the C7 arrived. It is night and day. Aside from some service bulletins, all is well 3 years later. Otherwise, as Jay Leno bragged - fix it with a hammer!

Allen

JerryU

Just sold my September 2013 built Z51 M7. Went thru 4 winters and if I shifted slow from 1st to 2nd got a small crunch when cold. However if I used more force and shifted quickly it didn't crunch. Never had an issue either way with 3rd.

Once the trans lub warmed never a problem even shifting slow with little force.

Hope my M7 Grand Sport being built next week is as good!

Corgidog1

No crunch even when cold for my 2015 M7

dvilin

A bit clunky when cold from 1st to 2nd but no crunch or grinding.

BELVIN20

My 2016 Z, same issue when cold, warms up, goes away. One would think a new better fluid would fix problem.

ersatz928

2017 GS : Crunch from 1st to 2nd, cold and sometimes hot....Tremec still hasn't fixed this design issue.....my C5 6-speed Tremec never did this (cold or hot).....

BELVIN20

Issue covered in another thread, seems to be nature of the beast, as soon as the M7 warms up, problem goes away.

Foosh

All Tremec transmissions in every make and model they've been used have exhibited the cold, 1-2 shift "balkiness," for as long as I can remember. I've seen the same thing in the Ford Shelby Mustangs, Dodge Challengers, Vipers, Camaros, Cadillac CTSVs, and every other "muscle car" it's used in. The exact same thing was present in both of my C6s, which were earlier versions (T56 and T6060) of the same transmission of today (T6070).

As far as I'm concerned it's a non-issue because: 1) It's only present when the trannie is cold; 2) it's a bullet-proof transmission that lasts forever; and 3) it may be the only manual left in the world that can handle over 500 ft lbs. of torque and is compact and lightweight enough for sports car use.

Steve Garrett

OP, your threads have been merged. Forum rules indicate that you can only start one thread about a single subject.


Cheers....

Maxpowers

When I got my M7 last year in the spring I felt it while cold (like others describe).

Since I DD my car I was a little anxious how bad it would be in freezing temps. It actually didn't get much worse to my surprise. After a few mins it shifts smooth.

Cchief

The problem still exists in my 2016 Z51 with 1100 miles, i found several bulletins that speak to the issue with no fix in sight. I filed a NJ Lemon Law claim and received a substantial check 10 days ago from GM because they don't want the car back, just to get you off their back.
My theory is that if enough people file claims, they will get off their asses and come up with a fix. Just me a guy yesterday that changed his fluid to Amsoil and says the issue went away. I also found a tranny guy that says its a combination of the clutch release, the compound rings and the fluid causing the notchy problem.

RVC

Mine does the crunch **** cold or hot...I pay no mind.

Snowwolfe

I been driving manuals since the 60's. Every one I ever drove shifts smoother once they warmed up. It's normal.

JoesC5

T56 wasn't to bad, but when they went with wider gears in the TR6060(and TR6070) the synchronizer design was changed because of less space for them. It's been an on going problem since 2008. GM(and Ford and Dodge) has tried different materials for the cones which have helped a little bit.

I just hesitate a split second when I'm going through the neutral gate to give the gears a chance to slow down to match the shaft speed, so the synchronizer teeth can mesh without the nibbles(which do wear down the sharp points and increase the likelihood of replacement further down the road).

PS- I have been driving 4-speed Muncie transmissions since 1964(in my new 1964 Malibu SS) and even now in my 1956 Corvette, and they don't have the problem. It is not a common problem in all transmissions with synchronizers.

Foosh

^

What he said is correct.

It's really no big deal and just takes a little time to warm up. It doesn't in any way affect the reliability or longevity of the transmission. They tend to last "forever."

ersatz928

It is a big deal when it does it even when the trans is hot.....

Foosh

That would be a different thread.