So I have this "whine" or "singing" that I hear at low speeds and I'm pretty sure I have it at higherspeeds but I probably can't hear it at those speeds. Before it used to be pretty faint where I wasn't sure I was actually hearing anything but tonight I drove around on some empty streets after a good rain and it's definitely more apparent.
I'm hoping it's my rear-end and not my tranny but If I stick it in first and cruise around it's fairly loud but if I shift into 2nd at low speed the noise dies down and is almost muted, does that mean it's tranny related?

This is what it sounds like...
http://www.youtube.com/watch?v=X3-HeP696Pg

I'm thinking it's my rear-end. I have Tru-trac in there right now. Could be on it's last legs? Any sure fire way to tell if my rear-end is going out? I just hope it's not the tranny.

 

So, I have heard of some 4l80e's having straight cut gears that whine in first. I believe the straight cut gears came on 4l85e's and some of the newer 4l80e's. (2006 and up?) Someone else might be able to confirm this.

Is this noise new, or just the first time you paid attention to it?

If the pinion bearings in the diff were worn out, you typically have a howl on deceleration. You can take off the cover and look for abnormal ring wear, but I think its the transmission given the fact that you got the results you did when shifting.

 

I would think if it were the rear, it would make that noise at all times--not just first gear.

 

most 80 whine a little. Like stated, straight cut gears as well as I think its just the nature of them. Seems most typical in first gear.

 

I was going to move this to the truck stop until I realized you meant mechanical whine

 

Sounds just like my 2003 4L80, kind of a hollow whine, kinda like exhaust rubbing the driveshaft IMO.... had it from day one, covered it up with a little blower whine, lol. Never a moments trouble out of it. My new 4L80 came out of a 2007 HD and is silent. Seems hit or miss as to which ones have the stright cut gears.

 

As long as it doesn't get louder I wouldn't worry about. That definitely sounds like the typical 4L80E 1st gear whine.

 

Alright cool, thanks guys. I never heard it when it was in the CC and unless I installed the converter wrong which I would of known by now anyways, I can't see it being something wrong in the transmission. I've put about 2,000 miles on the truck with this so called whine so if it was something rubbing and grinding I think it would of broken by now so I'll just live with it.
Someone else also told me straight cut gears as well, I guess I'll check the fluid levels and go on my merry way.