When I redline 3rd gear and shift to 4th, my gear grinds and it wont go in gear even though the clutch is all the way down. If I let the RPM's back down a bit, it goes in fine. Is my synchro damaged?

It's fine under 8500 rpms or so. And all the other gears work fine.

 

Could be? The only time I have issue shifting at high-rpms is from 1st to 2nd, and I believe that's due to me starting to release the clutch a little as I'm shifting, rather than waiting until the gear has fully engaged (ie: a side effect of my shifting technique when I'm shifting fast).

I believe the trans oil has a lot to do with shifting and smoothness thereof, so you may want to consider changing the trans oil or something like that. You could take it to the dealer and see if they can reproduce, but they may just bellyache about the high-rpm shifting in the first place...

 

I'm running royal purple gear oil in my gear boxes already.

Yeah, I thought they might bellyache about that too.. Just wanted to get some opinions first before I did that. I may just live with it since I dont drive like that alot.

 

Actually, it grinds anytime I try to shift into 4th from 3rd and it is above 6k rpms. It's exactly 6k. If i'm at 6100 it grinds.

does THis happen to anyone else?

 

I get solid shifts from 1-2 and 2-3 but I sometimes get the same results you (guy321) are describing going from 3-4. Usually it's when I'm being aggressive. And let's face it high RMP in 3 is pretty much above any posted limit! But I don't think I get it all the time. Just last week I was doing this shift and felt something "wrong" just before I let out the clutch. So I backed off putting it in neutral then back to 4. No issue. But I am watching it closely but haven’t gotten to the point of noting particular RPM ranges causing the issue.

Previously, I lost syncros in an Audi A6 6 speed … twice. The first time was a missed shift from 1 to 2 (so I thought) resulting in a progressively worsening situation that eventually lead to the replacement of the tranny. Then on the second tranny, knowing a little bit more of what to look for, I experienced a shift that basically no matter how I let the clutch out, would not go into gear. As in I caught the clutch release before I realized that that the tranny would not go into 2. My opinion was that something had damaged they syncro prior to my shift. If that was the case, there was nothing I could have done other than miss-shift. Thus, I assume that’s what happened the first time. I guess I’ve been watchful of this issue ever since. Maybe I just need to relax a little more.

 

Yeah, but 6k in 3rd is still within legal limits, and it does it there for me..

Your Audi, was that under warranty?

 

Yep, both times. Once at 5K and once at 10K. On the second, they told me it was a "user issue". This was Audi and not the dealer's call. So I told them to stick it and traded the car. I'd love to go back and find out how many additional tanny's that particular car went though over the past several years!