Sadly to say, it is MOST LIKELY and almost guarenteed to be the 4th clutch hub shaft. It has splines on the end of it that round off usually over 70,000 miles. They will all eventually fail, just a matter of time. Adding power and driving hard in 4th gear will add to this. Mine had sheered all of the teeth completely off.

The only way to fix it is to have a trans rebuild done. I also recommend getting the hardened shaft from ZZperformance.com.

I had a helluva time researching this when my car lost 4th for no reason.. got off the freeway after driving in 4th for 200 miles and when I got back up to speed, nothing, it was gone. Just like that.

SO, I figured I would post this info incase anyone else runs into this and tries to find the solution like I did. My situation was in -20degree temps and i thought it was protecting itself, not so. After I had my rebuild the builder showed me the part, it was so polished from rounding off that it looked like there were never any splines there to begin with.

I hope this information helps someone as I went nuts trying to find an answer for weeks, everybody just speculated or just had the trans replaced. It WILL run without the shaft splines but having to run it in manual 3rd will chew up it'* clutch in about 5,000 miles *happend to me* you will then lose 3rd. You will be limited to second which will also fail and burn the bands in the transmission that help the car get moving. Second will fail as it did in mine as I was pulling into the rebuild shop.

Good luck to all, know if it does go out you have roughly 5,000 miles to go in 3rd before it fails. I drove it like this on the freeway in 3rd for weeks till I saved the money to rebuild it.

Take care, hope this helps.
Adam

I believe GM actually came out with a hardened or strengthened shaft that they started putting in our trannies is '04 IIRC. Anyways, this is a problem, but mostly it is a problem if you try to accellerate at all in 4th. If you just cruise along in 4th without trying to accelerate or anything you should be okay, its when you accelerate that you start having problems because it isn't designed for it. As you said the part is available at ZZP and I'm pretty sure INTENSE has it too. The problem should be able to be avoided if you just never get on the gas very much in 4th. Downshift it to 3rd and then accellerate, because if you go WOT in 4th it will have that power for a second in 4th which can strip that shaft. We have 143k on the SSEi with the original trans, with mods, and no problem yet, but you just have to be careful about getting on it in 4th.

Shawn

........not sure I understand the problem?!?,.....any time you are crusing in 4th gear(anything under 80 mph,anyways)and you stomp down to accelerate,the TX kicks down out of 4th gear[overdrive] and into 3rd gear in a heartbeat,........the car never stays in 4th gear [overdrive] at most Any highway speeds,once you jump down on the throttle.I get sick of my car always shifting out of overdrive(back to 3rd gear) when you are going 40-45-50 mph and go to accelerate a little,so most all of the time around town (and even on some winding,hilly country roads) I leave the transmission in 3rd gear.........

Yes, but when you stomp on the gas the engine is producing power for a small amount of time in 4th gear (like a half second or less) before the trans drops down. This sudden power is what snaps it. So to prevent the problem drop the shifter down into 3 before going WOT.

Shawn

Correct, this is a GM hardened part and is included in 03+ applications with the 4t65e-HD. We both carry it as a convenience for our customers as it may be hard to source directly from a dealer.

Thanks for the info. I'll have to remember to never go WOT when in 4th gear.

It is the shock load that occurs before the shift that is the problem. There is not much at all in the trans keeping it in 4th gear, it is easy to burn or round off what DOES keep it in 4th by pushing it'* power.

My rebuilt trans holds the Torque converter locked so hard I can build up to 8lbs of boost in 4th. I had my PCM recoded for lower Throttle position ranges so it does not do it anymore, but you get the idea.. it can occur and our blowers make a ton of torque.

Just wanted to put this up as an FYI as when I was researching this issue nobody had an answer ANYWHERE.. so now there is.. or a very good idea of it.

Has anyone just had the clutch hub replaced?
Not sure the car is worth a fully rebuilt trans

This thread is almost 14 years old. Please do not post in threads more than six months old.

Thread closed.