Bob 33

During an otherwise wonderful recent track run, I no longer could downshift from 4th to 3rd, getting grinding if it would go in, even with careful rev matching. If engaged, 3rd runs ok, and there are no problems with other gears, or shifts (5 to 4, 3 to 1, etc.). Probably a problem with the synchros encountered by many of you, and a future problem for the remainder. I'll check with my dealer because it's still under extended warranty, but don't expect much help. Also, searching this Forum, I found a lot of grief associated with such problems, and people ended up paying to fix the problem twice, with recurrent problems. Not good.

This brings up the problem of what to do next and the ideal fix. For a fast, trackable street car, is a rebuilt GM trans, a new GM trans, or a trans rebuilt with more robust gears and synchros best? Who does this work best? And what will all of this cost?

Bob 33

Wicked Weasel

My transmission went this year. I could still drive it, but get on it hard and it was impossible to shift.

I was going to have GM replace it, but I forgot that I still had a line lock in my car and GM frown upon that.

If your car is basically stock GM should cover it. If you can talk to your vette tech then you mgiht be able to get the tranny upgraded. That would be the cheapest route to take and stillg et a good tranny.

since GM was not doing mine I went with a RPM tranny. It was a rebuild and it is much better than my stock one ever was. I took it to the 1/4 mile track last weekend and ran the gears. It is so smooth it is incredible.

BTW - when we drained the fluid in the tranny it was all black. It was nasty and I am sure my syncros caused it....

DALE C

Give Rodney a call at RPM transmission. He has a new 4th gear mod that should help a lot of the synchro problems as well as a lot of other well thought out improvements.
You may also want to check for any clutch or prop shaft problems, they will show up first in 3-4 or 4-3 shifts.

RAFTRACER

Gotta love extended warranties, especially if your dealer will honor it. I would get the G-force 3-4 shift detent keys and give them to whoever is going to repair your transmission and have them install them in the new 3-4 Synchronizer hub assy. The sheet metal ones you have right now have probably casued your occurance. These keys are $100.00, expensive for what they are , but well worth it in my opinion.

Bob 33

Aside from the cost of the transmission, how much time and cost is involved in exchanging the transmission in a stock 03 Z06?

Bob 33

John Shiels

1100-1400 my bill was near 2,000 parts and labor and and it popped again in 140 miles at VIR They said in may be the clutch dragging or else after 60,000 trouble free miles I can't drive. Imprints on the cone and the ring dog broke like the first time I am afraid to drive it. If it pops again don't know what I'll do. I'll be disgusted and just leave it in the garage for 10 years. I put all the upgrade parts in also.

gpm30236

Mine went this weekend at Road ATL, intially difficult to get into 5th then a couple of laps later, downshifted to 3rd into 10a and then when trying to shift to 4th would not go, by the time got to the pits, had only 3rd and reverse. Tranny had 60 K, on it, and about 40+ track days. hope the new one lasts a bit longer.

Bob 33

What were your various experiences with new GM replacement, rebuilds with stock GM parts, and rebuilds with upgraded parts, micropolishing, etc? A search of the archive indicates a lot of lingering transmissions problems after presumed repairs, rebuilds, etc. Is there any consensus about what is most likely to work, what not, and what is a total waste of time and money? And, assuming a good replacement unit, to what extend is the installation and calibration of the shifter, etc. critical and technician dependent?

Bob 33

Carl Johansson

What transmissions are you guys running? the ZF - 6's?. I keep reading posts from guys who say it's a "bulletproof" tranny - of course thats typically in reponse to "toasted my ZF 6 - GM wants fort knox to rebuild" posts.

i have an old C-4 - my brother runs an older C-3 - we went with the tremek 5 speeds as replacements (in his we replaced the AT - in mine - the POS 4+3).
we run the cars at tracks all over western US and have had exactly 0 troubles with the keisler tko 500 kits.
(we looked at going to ZF-6 as well as the richmond - to many red flags in either case!)

Carl Johansson

gpm30236

Up to now the standard Z06 tranny , had been freshened 60k miles ago , has about 40 track days on it, Now getting beefed up . Also adding the tranny brace.