3rd gear grinds, wouldn't engage (08 Z06)

[335itoz06]

I can not shift to third gear if I rev/accelerate hard in second gear to redline. The shifter would not allow me to go, it will not engage, it grinds.

This only happens if I take rev the engine to redline or close to red line in second gear(shifting to third).

All other gears work fine. The third gear also works fine as long as you shift at lower rpms (like up to 5500-6000rpm) above that it will grind.

I can also shift fast from second to third and third gear works fine but the problem is when I rev the car to red line.

The dealer suggested changing the oil to a special custom blend(that is what they suggested) but I think it has to do with the shyncros. What do you guys think?

[panzer]

Go to another dealer this one is out to lunch on his diagnosis and solution. You have a essentially new world class car that is supposed to shift gears. You dealer is avoiding the work. Something is wrong and changing lubricant is not going to do it as the oem fluids are adequate for the job.

[4wheels]

First, I would make sure the trans if completely warm before driving like that.
Second, I would check your shift style & speed to make sure you're sliding it in the proper gate "exactly".
Third, how many miles do you have on it? My '08 took a couple thousand for the trans to feel like it loosened up.
Also, don't "force" the shift if it doesn't want to go. That will guarantee a grind. If it resists you, then something's wrong, either temp, synchros, shift style, clutch style, etc. Make sure your timing on the clutch is "right" for this car. When I go between several of my cars (all sticks) my timing gets screwed up slightly as they all shift differently. The Z06 just happends to have the slowest shift of the bunch so I have to adapt...

I've tried the aftermarket oils, and they only make a subtle change, they're not a life saver. My trans got better with a few miles but still needs to be pampered when cool. Even when warm, it sometimes feels slightly notchy in 2cd and 3rd.

[zeta08]

Firstly, it's hard to know anything not driving your car, and I don't know much anyway!

OK, here it goes anyway.

I think something is "wrong" sort of. I agree with the above tips mentioned too. All I know is a local racing company who races stock tremacs in Vipers uses stock dodge fluid and blueprints them all before use to make sure the shifting is precise, in their words, to prevent mis-shifts, which when really racing can be really bad.

Think about it though, do you really think your new tranny syncros are gone already knowing the car shifts fine under normal use? It's more likely the syncros just don't like the exacting nature of high RPM shifts. But, hey, if you can't tolerate it, keep going to dealers until they replace it. I think that's a reasonable approach. And I think changing the fluid to what the dealer says is as well. Jump through his hoops and he may get tired of watching you do so!

I think the tranny's are good, but if you really want to race it as you are doing, you need to realize you are doing so with a mass-produced tranny and it may not like it (dealers may not too). I'm not saying I do anything different, just that maybe I give the tranny the extra 1/10 sec to get into gear knowing that I'm the driver / owner of this ride.

I like knowing my car's bro did a 10.98 1/4 stock, that doesn't mean I'm going to try that, for example.

That being said, one middle ground fix would be to get an aftermarket shifter and change fluids. This may make your shifts more positive (not that you can't drive, it's just less room for error) and only costs about $300 installed. If mine doesn't "break-in" more - it grinds a touch if you shift anything other than slowly until totally warm - then is fine, which I think is normal, I'll get a new shifter. But I'm waiting until about 5K and a tranny oil change before deciding....Then knowing me, I'll get one. Good luck, keep us posted.