Getting used to this car... grinding synchro!
 

Hello everyone,

I purchased a 2010 C6 with 61k miles about two weeks ago. Love the car! However, I'm having one hiccup...

The shifter engages into gear directly and obviously, with one "notch" (almost like a "plop") going into every gear... except for second gear at low RPMs. If I'm powering through first gear, shifting to second is very direct and deliberate. However, if I'm at low RPMs (perhaps shifting from first after starting off slow or from third approaching a light or corner), second gear is a bit vague and seems to have two "notches" to push through.

Unfortunately, I have already ground the second gear synchros three or four times!! Pushing through the first "notch", it seems like it's in gear, so I release the clutch... BZZZZZ!!

Terrible, or no big deal? Normal experience getting used to this transmission? This seems to be 100% user error, not a transmission problem.

​​​​​​Thank you!!

Does it go away after the tranny warms up?
when I take off when the tranny is cold I granny shift it into 2gear for 5 blocks then I'm ready to go. Just make sure your pushing the clutch all the way in also.

Hi, thanks for the reply!

It's not that it happens more when the car is cold or warm.

What I'm trying to say is that second engages seamlessly when higher in the revs, but *sometimes* feels like it has two "notches" to push through to engage at lower revs.

It's completely my error... It feels like it's in gear, but really the shifter is only "half way" there, then I let the clutch out too soon! .....Grind!!! (Don't get me wrong; the transmission is not routinely grinding when going into second gear).

So, I guess I'm not looking for a mechanical diagnosis, but rather would like to know if anyone else has experienced this? And do the grinds justify transmission fluid flush?

Could it be CAGS kicking in? if you keep pulling it into gear, do you end up in 4th?

Is CAGS the skip shift thing? If so, nope, it's not that!

Imagine you're going real slow, approaching a parking lot entrance... gauging angle and speed so as to not scrape up the front end... The big choice is first or second gear...ultimately decide second... feels like it's in, but it's not all the way....clutch out... GRIND

It may be as simple a adjusting the shifter. Here is a link to a video by Froggy. He has a lot of good videos on C5's and C6 Corvettes. The video shows the procedure for adjusting the shifter on a C5 but it is the same as for a C6.

Check the fluid in your clutch reservoir as well, if what you've got is dark brown/black, search these forums for the 'Ranger Method' and follow the protocol.

Thanks for the advice everyone!

Can anyone elaborate on the detriment of grinding synchros of a manual gearbox? What is going on and how bad is it?

Why does fluid make such a big difference on how gears mesh together?

I had similar issue with second gear. I opened up shifter box and noticed the bushing was worn out and dry. I replaced shifter box with lower mileage one (used), changed transmission fluid and problem is gone. i'm not saying your problem will get resolved doing this but its worth trying.

Grinding synchros is not good. Eventually the teeth will wear down and will will make it harder and harder to put it in that gear.

As for the fluid, is allows the various surfaces of the transmission to slip past each other. And some transmission fluids seem to loose their lubricity properties after a while. Some loose their performance well before the car maker recommends the fluid be changed. Sometimes a transmission that feels like it something majorly wrong inside only needs the fluid to be changed.

If it were me, I would do all of the things recommended here. Change the fluid. Do the ranger method to replace your clutch fluid. Try the re-adjustment procedure on the shifter.

You do not want to keep grinding the gears because eventually you will need a rebuild or a new transmission. Much cheaper to do simple maintenance.

in every sporty car ive driven, 2nd gear has a stronger synchro set (for the 1-2 shift!) that takes a little more force to engage. It also takes a little while to heat it up to get it feeling right.. To mitigate, try this in this order:

1. "ranger method" clutch fluid swap
2. transmission fluid swap (I use redline ATF - yes ATF in the MTF t56/t6060 uses atf...)

3. before "starting" the car, pump the clutch 3-4 times.
4. before starting the car, cycle it through the gear 1-6.
5. after starting the car, cycle it through 1-6

if its still grinding, master cylinder adjustment, lower box swap, or a trans overhaul may be necessary...If you can reach the slave cyl, bleed it too.

This right here is probably the best starting point for mitigating any further damage if you have started biting your gear/synchros already.

Also for what it's worth, I'll rarely shift 1-2 under 4k RPM, it's not smooth, better to just skip to 3rd or 4th. In my opinion it's more there for hard acceleration and downshifting, the ratio doesn't mesh well for cruising.

They will be more notchy when cold....I know its the obvious but is it more important cold that you depress the clutch fully. Its easy to be lazy but you learn the speeds it likes and get in the habit of getting the clutch all the way down and everything works easier.

Thanks again for all the responses!

I was about to report that this hasn't happened in a while... but I just goofed up and did it again yesterday!!

Oh well......

Trying to be more diligent...

Where in Florida are you (it's okay to put the city in your profile you know)?
Maybe another forum member with a M6 could compare shifting between the cars...

I updated my profile!!

I really do think it's user error... Who knows?

Yikes, that lets me out...

BTW, why are you sure it's not the skip shift?
Personally, I consider the skip shift "feature" to be dangerous. I installed a skip shift eliminator when I had my 94 Firebird. The previous owner of my C6 had it tuned on a dyno and while they where in there, they disabled the skip shift thankfully.

I would highly recommend doing the clutch flush if you haven't yet, you might be really surprised. (Costs about $25 total in tools/fluid, just need a turkey baster/syringe and DOT4 brake fluid, not 4.1/4.2/4.3 or 5.)

Dusty/dirty fluid = significantly slower/sloppier engagement which will easily lead to bad shifts. Do you feel a lot of vibration in the shift knob when shifting?

Also, not my image, but this is a decent reference, most of the cars I've seen that complain of your problem have fluid that looks like the right on this picture, you need it to be nice and light like the left bottle though.
(If it's really bad, you might need to install a remote bleeder and get the dust out of the slave/do a full flush)
http://www.irv2.com/attachments/phot...b68acedfd8.jpg

Check your clutch master reservoir, if the fluid is that hue, you need to do the Ranger method flush.

What do you mean by "Yikes, that lets me out..." ??

I don't think it's the skip shift because: it's not quite at the right RPM, the 1 -> 4 light does not come on, and there is no resistance to pushing the lever into gear.

Thank you for the advice!

Thank you!