ccmano

I've posted on several threads about this strange whine and even launched one dedicated to this issue. Bottom line... Finished the install of a low (18k) mile 07' Z06 Trans and diff combo into my 47k mi. 05' Z51 today. All I can say is OMG! it's like driving a new car. The background on the issue is outlined below. But I had no idea how bad my trans was! I now have zero drive train noise, the interior of the car is soooooo much quieter than before. All the clatter and noises I thought were normal apparently weren't. I can actually shift into reverse without even giving it a thought, goes right in. Strangely, otherwise the old trans shifted smoothly.

The added benefit of the Z06 setup is the diff cooler and generally more robust construction. Installation was pretty straight forward only the reverse sensors (spliced the wires from the two connectors into one connector) and trans cooling return line (a compression fitting and my handy dremel solved that) had to be adapted. I have to thank Miles at Cleveland Pick a Part, the trans/diff they sold me was pristine, shipped in a specially built create and arrived in a week direct to my house damage free. All at a great price.

Oh... And I now have for sale a perfectly good 47k mile 05' 3.42 diff, a very nice 04' 25k mi Z06 3.42 diff with the entire setup to install as a retofit in an 05' and an 05' Z51/MZ6 trans core. Those will be posted in the for sale section.

Here's the back ground on the issue...
H


"I started this conversation on an older thread where someone was having a similar issue. Thought I would put it out there by itself and see if I can get some more input.

"Changed to Redline fuids in the trans and diff about 8k miles ago. About 6 months later I started hearing a faint whine from the back of the car at higher speeds, 65-80 mph and only in 5th and 6th gear and only on throttle. Over time it got worse and louder, eventually I could hear it all the way down to 2nd gear and got the whine both on throttle and deacceleration. When coasting even in gear it almost went away. I was convinced it was the diff. Took it the local place that specializes in diffs only and is very well versed in corvette. If I said the name you would know it. Two people there drove it and the consensus was it was the diff. They did say they could not be 100% sure till they opened it up. Based on my experience I agreed it was the diff. I decided to swap the diff myself. I bought a 7k mile 04' z06 diff and did the retrofit swap. Not difficult just time consuming. Finished the car today. We'll... You guessed it, the whine is still there. Process of elimination now means it has to be the trans? Very frustrating to say the least. Just goes to show you can never be 100% sure."

"Yeah not as straight forward as one might think. The transmission and diff are right next to each other at the back of the car making figuring out which it is difficult. Of course the drive shaft bearings are another possibility as are the CV joints. I keep trying to come up with a way to narrow this down further. I do have three new observations in my case. I changed the trans fluid today to see if there was any impact on the noise. It made absolutely no difference. I noticed that if I cruise down the freeway at 70 or so mph, uphill, downhill or flat road and press the clutch in and leave it in gear the noise goes away completely. This means that everything from the driveshaft to the wheel bearings are still turning at current road speed. In turn, this means that the noise is load dependent (you would think some noise should persist particularly up or down hill) or it's not any of those items. The last observation is that the whine doesn't "sing" (if you know what I mean) like gear whine tends to, it sounds more like a supercharger whine with almost a high frequency buzz to it.

What does all this mean? Not sure yet. Throw out bearing? Still working on it."

RicK T

Just for clarity.

You're saying the old trans was making all the unusual noise? Or was the diff bad too? TIA

ccmano

It was the trans the whole time. Installing the 04' Z06 made absolutely no difference.
H

5knives

I'm glad you got your issue fixed, although it sounds as if I'll have to do the same, which doesn't make me happy. Were you able to determine exactly what the trans issue was and why it occurred?

ccmano

While I'm tempted to tear down the trans and try to determine the cause, it's really pointless. The trans will need a complete rebuild one way or another. I don't have the tools or knowledge to rebuild it. I'll leave that to someone who knows what their doing. Strange though that, at least from what I have gathered from the forum, Z51/MZ6 transmissions mostly seem to be the ones having this issue.

One recommendation I do have as a result of this. If you have your trans rebuilt make sure it's a complete rebuild with all new bearings plus all the usual items. In researching this I discovered that rebuilds range from simply "fixing" whatever they find to a host of common "upgrades" to major upgrades for the racers.

If mine is any indication the condition only gets worse with time. Good luck getting yours resolved.
H

5knives

Understood, and thanks for the advice Mine isn't horrible at the moment, but like you said, it may get worse. I'm going to just deal with it for now and see how it progresses. If/when it gets to a point where I need to replace it, or a great deal on a trans comes along, I'll attend to it then.