[autoxal]

Thanks - I agree - thought I'd found it with the Royal Purple but they don't make anything for hydraulic clutch systems.

The synthetic fluid is for the transmission... nothing to do with the hydraulic clutch (stock fluid in clutch system is already synthetic). The issue with the standard fluid in the transmission is that when it's cold, and it "thickens up", it screws with the sychronizers ability to function... thereby making quick shifts difficult until it warms up. Replacement synthetic fluid is able to maintain it's viscosity to much lower temps.

 

[Z28+23]

The 1st-2nd and 2nd-3rd shifts in my 2014 Premier Z51 are fairly "notchy" until everything gets warmed up. Do you think a MGW shifter would help that? I don't race or run it hard. Just wondering what your opinions are as to what difference a MGW would make.

Use the RANGER METHOD to change your clutch fluid. Use a quality Dot-4 synthetic brake fluid. Even in Alabama my M7 likes to warm up. I did change to a Hinson short throw shifter.

 

[bob67327]

(Apologies in advance for a long, boring, reply here! bob)

The test for a "dragging" clutch in the old days was to shift into reverse.

The transmission should be thoroughly warm for the test. Let the car idle in neutral with the clutch engaged. De-clutch (push down on the clutch pedal) and wait a second or so (to allow the spinning gears to stop) and then shift slowly and deliberately into reverse. If there's any gear-grinding noise the clutch is not releasing. I experienced that numerous times in the "old days", when the clutch throwout bearing was worn (in VW's it was a carbon bearing!).

With apologies, I don't know if the C7 with the M7 transmission has synchro rings on reverse. I've never had a car with that (unless our C7 has it?) but I think some transmissions do now (?).

I'm SURE most of you readers already know if the C7 with M7 has synchro rings on reverse (??). Maybe I'm wrong and nobody has it??

This test would be far less definitive if the C7 with M7 does have snychros on reverse. You'd have to try to "feel" the synchro rings matching the speed, and it would feel the same for both 1st and reverse. With experience you could feel that by sensing whether it felt the same when shifting immediately after de-clutching compared with waiting a second or so, but engaging the gear with the same pressure on the shift lever. If it feels the same probably the clutch is not releasing.

BTW, that "feel" of the synchro rings matching the speed is exactly the same feel you'd sense making a low speed shift without using the clutch pedal (without de-clutching). But nobody would recommend doing that! It's easy to do at low speeds (but to sense the difference you'd need to try it shifting quickly and then increasingly with a greater hesitation, for upshifts without using the clutch). If you upshift with exactly the right hesitation you do not need to declutch.

In the 1950's in Germany the driver's license test required demonstrating the ability to drive a car with a non-synchromesh transmission (then standard on the not-for-America VW's). Up-shifting a non-synchro transmission with the perfect hesitation is exactly the same whether one uses the clutch or not. The transmission gear-speeds are perfectly matched with the car's speed, making the clutch completely unnecessary to effect the upshift.

Of course downshifting was far more difficult, requiring "double clutching" (double de-clutching to some) and speed matching with the clutch engaged. You had to know (to feel) the right RPM to speed match and also the right hesitation to engage the lower gear. Long ago I could do that; no more!

Apologies for being a long-winded old man! Probably every one of you already knew all that! Happy pandemic ending (eventually) to all of us, bob

 

[Stingraydan]

stevec, since you stated it works ok once warmed up, I agree with your thought about staying with your current set up. My understanding is the MGW shifter is more precise than the OEM.

 

[Stingraydan]

Hi Steve. The issue is not going to be resolved with a more precise shifter. The issue is with the Tremec manual transmission which does not synchronize properly from 1-2 and 2-3 gear. Plain and simple. This was confirmed by a Tremec Design Engineer who would not provide me with his name as well a gentleman I met who happens to know a higher up in Bowling Green. You may want to try a higher viscosity full synthetic gear/transmission oil called Synchro Shift II. It worked for me! Although it took approx 1,000 miles for the mentioned synthetic to finally do the trick. Since I live in the Richmond area I had the old trani fluid flushed and replaced by ZIP Corvette!

 

[autoxal]

The solutions provided seem, to me, to be heading in the wrong direction... talking about dragging clutch (had this in my '67 Firebird, when the clutch diaphragm collapsed) or hydraulic clutch fluid break down. Stubborn shifting, for a few shifts, prior to warming up when cold, points directly at trans fluid that is too viscous (and dragging on syncros). If you feel the shifter 'kick' back just before settling in position... (!ONLY when COLD!)... that screams fluid viscosity related to me. Synthetic transmission fluid does not "thicken" like conventional "dino" oil when it is cooled... I have been a huge proponent of synthetics since them becoming mainstream in the early eighties. Ability to stay "thin" at low temps is HUGE for engine oil... or any other automotive fluid. Several years ago, someone posted exactly what the stock fluid spec was... (I have it printed in our Wisconsin home ☹) need to match with synthetic. Had EXACTLY the same issue with my 93' 1LE Camaro 6 speed... replaced with a Red Line synth... bingo... cold kickback gone. (The fluid in that car was automatic trans fluid that was formulated to be compatible with adhesives used on some internal friction pads - important!)
SORRY for being so wordy... but have a strong feeling that this is the solution (now to diagnose my own cold clutch shudder... yes, I did Ranger flush of clutch🙂). Be kind.

 

[bob67327]

Thanks for your wisdom, Autoxal. My instinct is that you're right. However, can one learn to shift with the correct (shorter) hesitation when the transmission is cold? Maybe even double-clutching the upshifts? In my experience the feel of a cold transmission disappears quite soon when driving from a cold start. Plus, of course, there are other reasons to drive gently when all systems are cold.

I've been doing the "Ranger" thing on my clutch reservoir very frequently, even when the fluid there is barely discolored. However, I was very "late to the game" and the first time I did it the fluid was black! But now after 92,000 miles, 90% "highway" miles, the clutch still seems to be working fine. Knock on wood. best regards to all, bob

 

[autoxal]

Thanks for your wisdom, Autoxal. My instinct is that you're right. However, can one learn to shift with the correct (shorter) hesitation when the transmission is cold? Maybe even double-clutching the upshifts? In my experience the feel of a cold transmission disappears quite soon when driving from a cold start. Plus, of course, there are other reasons to drive gently when all systems are cold.

I've been doing the "Ranger" thing on my clutch reservoir very frequently, even when the fluid there is barely discolored. However, I was very "late to the game" and the first time I did it the fluid was black! But now after 92,000 miles, 90% "highway" miles, the clutch still seems to be working fine. Knock on wood. best regards to all, bob

Agreed... even with my clutch engagement 'shudder'... it's just a few minutes of operation... and it's gone. As long as I'm not doing damage to anything else... I can live with it... maybe, for a while...

 

[stevec]

Agreed... even with my clutch engagement 'shudder'... it's just a few minutes of operation... and it's gone. As long as I'm not doing damage to anything else... I can live with it... maybe, for a while...

Kind of what I decided as well. Should be driving "nice" anyhow until everything's good and warmed up so I just go easier and skip 2nd until then.