My searches have not found a direct answer to this question. First, some background...

I have a Z06 with about 37K miles on it. It grinds when shifting briskly into 4th gear. It is worse when cold, but even when warm I always beat the synchro by shifting in one firm motion, and pretty much never grind if I use the "two-finger" method which forces a split-second pause at the detent. I would say it is not that smooth overall but no other shifting problems.

I bought it used about 6 months and 4K miles ago. It had a Hurst shifter installed. When I test drove it, and for the first month or so, the tranny seemed fine, if a bit notchy. Changed out the Hurst for a stock shifter, being sure to check the alignment, and it still seemed fine for a while. Perhaps I was still shifting cautiously, perhaps not. It did not have the skip shift override, and I did not have an opportunity to change that for the next 3 months. I began to notice that when the 1-4 activated, I might occasionally "grind" a shift because I was letting up the clutch a split-second early as the detent worked its "magic." Within a month or so, I began to really notice the grind under what I would call "normal" shifting, which I could avoid via the aforementioned pause at the detent. It goes right into gear and does not pop out, but the griding feel is pretty sickening. I have since changed the fluid and installed the 1-4 eliminator. The symptoms have not changed.

So, I am reasonably sure that at this point I have a bad synchro. Knowing that a rebuild is minimum $2K in these parts, and that a new one is about $4K installed, I am inclined to just keep perfecting my "delicate" 3-4 shift and riding this out. So, finally, the questions:

• Should I expect rapid deterioration of the tranny from this point, or can I nurse it this way (which, really, is barely nursing it as I can still shift briskly into the other gears) for a long time?
• If I do further damage, will it make the inevitable rebuild that much pricier?
• Can anybody recommend a top-notch Vette tranny specialist in the Philly/Wilmington, DE area to take it to for another look see and/or rebuild when I must?

Thanks...

 

For the cost of a rebuild and all the work involved I would practice my shifting more and ride her out. What kind of tranny fluid did you fill it with?

 

That was plan A. Funny how I haven't had to "practice my shifting" over 30 years of driving with three pedals, but there's a first time for everything

HOWEVER, I have just chatted with a local guy -- Forum member who PM'd me. He knows tranny and rear builds, and does this work on the side. Seems to be a great guy and knowledgable. He can do it at a good price (better than the big shops or dealers). I am doing my diligence now via references, reviewing his posting history, etc. Assuming he's what he seems to be, it makes sense to get it done right (he would do a bit of a "build" with the billet keys, bronze pads and the upgraded 3/4 fork) and be done with it.

BTW, my regular mechanic changed out the 12 year-old fluid with Dexron III ATF about 3 weeks ago. He said that's what's recommended and the first thing to do. He said if it continues, then go to another type before doing a rebuild. He's a good guy, local and convenient, and has a long history with Vettes. But he is not cheap and if I can do better with a Forum brother I wil definitely go that way...

Thanks for your advice

 

If you're near DE, give John Hicks a call (horsepoweraddicts). I was experiencing grinding - initially from 5-6, but eventually every gear would grind at some point. I initially just wanted an LS7 clutch & LWFW installed, but I ended up having him rebuild the trans and swap out my 3.42 for a 3.90 rear as well. I'm very happy with his work. Honest guy, and great pricing.

 

Good luck,post back and let us know how you made out. I have changed my tranny fluid twice now and I used royal purple both times. It seem to help the shifting, made it smoother.
BTW, you might want to get your rear end oil changed to if you havent done it. I usually change it the same time I do the tranny.

 

I would also recommend trying different fluids first. If that does not help, just don't let the grinding continue or it will cost you more money. Sure sounds like a synchro issue.

 

Change the trans fliud FIRST before you over troubleshoot your self into doing stuff that doesnt need to be messed with.

Contact Forum Member SUBDRIVER and get some AMSOIL Torque Drive ATF. Its some of the best T-56 trans fluid on the market!



If that doesnt resolve the issue,, please let us know.

Bill Curlee

 

I will do that! Thanks...

First, kudos to member tom01ss, who does some LSx engine and tranny/rear work out of a small shop in Clifton Heights, PA. He invited me to his shop last night to discuss the issue and show me, on an open T56 he had in his shop, what likely was wrong, and why. Patient with me and a nice guy.

Long story short, it was rush hour and took a while to get to Tom's shop, so the car was quite warmed up by the time I got there. When we took it out for a "demo," I was amazed that the problem did NOT occur. And we both tried, shifting very aggressively at various revs. Embarassing but probably great news.

Conclusion: I would get so spooked by the occasional 3-4 grind when first driving the car, that on longer excursions I most likely had internalized the cautious approach by the time I was on the road long enough to bring the car up to temperature. So, I probably never did shift aggressively under such conditions and never did experience grinding when the car was properly warm.

Tom's thinking was very slight 3-4 synchro wear, and far better to try another fluid (I think he uses Red Line in his) rather than open it up -- just continue to practice caution on short drives and only "relax" after 15 minutes or so.

All's well that ends well. I may well need the tranny rebuilt someday, but I think I've dodged a pricy bullet for now...

 

I briefly read your post and did not see anywhere a suggestion to bleed the clutch slave cylinder. I had similar issues and installed a remote bleeder and was AMAZED at the improvement in shifting after bleeding my clutch hydraulic system.

I'm not suggesting installing a remote bleeder, although that was a great upgrade, I'm suggesting bleeding your clutch system. FYI, the Ranger method will not help this problem. Good luck

 

Thanks Bill.

AMSOIL Torque-Drive Synthetic Transmission Fluid (Product Code ATD1G)

I agree with Bill that I'd try the simple low cost things first like changing out the fluid before jumping right on an expensive rebuild, particularly after reading your last post.

If you'd like to try the AMSOIL, more than happy to get AMSOIL products for forum members at dealer wholesale pricing, about 25% below retail, via the AMSOIL Preferred Customer Program. Drop me a PM if interested.

 

Interesting observation. The clutch FEELS excellent, with good take-up and engagement point. Maybe that proves nothing, though -- can one feel when a clutch slave cylinder has air in it?

Next time I have it in with my mechanic I'll suggest he check this out because it can only help.

 

Has the clutch hydraulic system ever been bled on your car? That would be my first question. If you are driving a C5, you have at least 9 years on that fluid if it's never been done. Think about that...

The problem I experienced was clutch dragging, which only manifested itself when the trans was cold between shifts, notably 3-4. It got worse with the change to Amsoil, but that had nothing to do with the oil and everything to do with the clutch hydraulic action. I would not be suggesting this PITA service unless I thought it may solve your problem as it did with mine. I run a short shifter with zero issue now.

BTW, I run Amsoil Torque-Drive and and couldn't be happier with it.

 

If the fluid change doesn't repair the problem, please contact us for your transmission needs. We specialize in drivetrain.