Ok, here we go friends and transmission gods. I just purchased this 2004 quicksilver Z06 (30k miles) about 1 month ago, and I am having some issues with the trans. Under normal driving everything is fine, but when I do a WOT 1st through 4th run I encounter blocked gates (usually 4th, but sometimes 3rd). Today I got blocked going into 3rd and then got completely locked out of everything. The shifter was locked in the neutral position. I had to totally stop and let it sit for a few seconds and then I hear a low decibel click which I also felt in the shifter in-turn freeing up all gates. I thought maybe I was having clutch hydraulics issues (slave not fully disengaging pressure plate) so I bled the slave feeding a pint and a half of new fluid through her. I am guessing since the problem is still here that was not the cause. To clarify shifter, clutch/PP & hydraulics are stock.

Possible causes:
1. 3-4 shift fork bent (does this only cause problems upon WOT shifts and not normal driving?)
2. 3-4 blocking rings/ syncros worn (I have had a little grinding once the gates free up, it goes away)
3. 3-4 shift fork pads worn (usually causes shifter to kick out of gear not block, but hey)
4. Shifter assembly mis-aligned? (I have heard that the linkage from Tq tube to trans can get out of wack)
5. Trans fluid (low, old, crappy???)
5. clutch hydraulics (Master & Slave are not leaking and I just bled them)


In my 02' 408ci SS I went through numerous T-56s. Usually due to blocking ring wear. I only bent one 3-4 shift fork, as I then upgraded to a Viper forged steel 3-4 shift fork. One T-56 totally locked up on me on the freeway ! But with all those experiences I never got blocked from a gear and then locked in neutral like this. What is going on here fellas?

Thanks,
Matthew

 

Bump

 

Hi SilentFright.

That's a very good, descriptive write up. Makes advice a bit clearer.

Your 2004 Car should be under warranty. I'd take the car to the best-repped Chevy tech in your area for a careful examination and diagnosis.

It could be the clutch is not properly releasing. You did the right thing in bleeding the hydraulics. Assuming that was done properly, air in the line via debris is pretty much ruled out. But the clutch can still be getting an improper release, due to failed parts.

I would assume the previous owner had this issue too. So the likelihood of some collateral tranny damage is fairly high, even if the root cause is the clutch.

If these symptoms manifest themselves only under high speed shifts, I'd suspect the clutch.

Either way, you will have decisions to make on whether to stay with a stock clutch and stock tranny parts or go for upgrades that will better tolerate hard driving.

I ran the stock clutch and never had tranny issues. But yours had a previous owner whose shifting skills are unknown.

Best tranny builder I know is rpm transmissions, in Indiana. Rodney is the owner and drives a Corvette. Many guys ship Rodney their trannies for hardening. For clutches, I'd go with Cartek.

The dealer should be willing to install the revised parts under warranty if you furnish the parts. Same labor cost, billed to GM.

Good luck. Let us know your progress.

Ranger

P.S Here is my standard cautionary note on clutch replacements:

Four small suggestions to those wishing to swap out their clutches.

(1) Seach the archives (C5 Z06 and C5 Tech) for the words "clutch" AND "vibration" because there is a history of clutch swap woes you need to be aware of.

(2) Choose your installer carefully. If you don't, the odds are good that you will not be happy with the results. You want a technician with a lot of (favorable) experience in swapping C5 clutches.

(3) Insist that the new clutch assembly be sent to a reputable machine shop for balancing before the installation. Do this even if the istaller insists it's unnecessary.

(4) Before you drop your car off for the installation, be very careful to memorize how much your shifter vibrates under various conditions.

If you choose to shrug and ignore this advice, the odds are that you will end up with notable drive train vibrations, originating from the clutch assembly, and you will have a hard time getting them resolved by your installer or anyone else.

 

Thanks Ranger, I really appreciate your advice! Looks like I will be replacing/ upgrading the clutch/PP, hydraulics & checking out the transmission for wear.

 

Holy Crap,you are hard on trannies.are you using the clutch when you shift?lol.I have a buddy that changes trannies weekly in his stang,he even has them race prepped tremecs.Driving style may help your tranny woes.Good luck.JER

 

AutoX events with the 02' SS were very hard on the T-56. Especially with over 600 flywheel horsepower. The time it locked up was due to builder error. He heated up the mainshaft to the point where it was glowing just to remove a gear assembly. Unfortunately he used the same "expanded" mainshaft in the rebuild. My Doctor Evil T-56 has lasted for the last two years of AutoX punishment without a single problem.