NukeC5
I see your point. If a driver is hotrodding the car from the factory without a good break in period it would definately cause uneven or distorted wear on the gears eventually causing the whine problem. I assumed that Chevy would have put heavier duty parts on a Vette but I guess no matter how heavy duty, without proper break-in people will have problems.
It just seemed odd to me that so many people were having this issue. I passed up buying a 98 because the seller said it had this problem. My reasoning for thinking that maybe it was a Factory issue is that C5s are the first year they moved the tranny to the rear end of the car and drivetrain mis-alignment could also produce a whining noise.

 

The differentials are tested from Getrag for noise before being installed on the assembly line. I think the whinning developes from lack of servicing the fluid. Most C5 owners don't service the diff unless they start hearing noise but by that time it's too late. These diffs only hold 1.8 qts and often reach over 230* F at highway speed. I recommend road course (HPDE) guys to replace the fluid after every event and all of them with our built units have stood up over time without any noise issues. The magnet catches most of the metal particles but that is the abrasive that starts to eat each other IMO.

 

I agree with the need to change fluid. But this problem occurs in cars with 30k miles!!! Mine developed the problem at 55k miles. The service interval is not even till 100k on normal driving, and 70k with harsh conditions!!! I just find it crazy that it happens to so many people.

 

The 98 Vert I bought was early model (purchased in 97) it has 71k miles and was owned by a couple that didnt abuse it but were not afraid to let her rip now & then. I have zero gear noise so I was just wondering if G.M. changed something along the way?
Also, Im wondering if there are bushings or supports that could get out of kelter just enough to throw alignment off eventually causing a noise issue?
Just tossing out some ideas.

 

Local shop said they had a customer that would change the diff fluid with every oil change, it too developed the whine. My vette had 35k miles on it when I bought it and had all the fluids changed. I don't really know what kind of life it led before I bought it, but I never abused it or really even did any "spirited driving" (have an 11 second Grand national to abuse, which oddly enough with over 500ft.lbs of torque, line lock and many launches with slicks doesn't have any issue with its rear end at 158k miles) but by 57k miles, my vette had the whine

Now with Ricks built diff, I'm going to change the fluid quite often, doubt it's every oil change though

 

What blows is that I have a brand new stage two 3.42 diff from RPM, and because I put poly couplers in the TT and used a Pfadt tranny mount, you hear the diff anyway! Its not screaming like before, but you definitely hear when its engaged and on deceleration.

 

Many years of driving older GM's and a few times over the years I have had to pull a Driveshaft and retorque the pinion nut that has developed a bit of play causing extra lash.

From normal wear of bearings? or is the crush washer distorting,or is the nut just backing off the pinion. Not sure. happened to my Nova, but those gears had been removed and probably no new pinion gear nut installed/Loctited. My DD s15 with 245k plus was also visited and it quieted down after retightening at around 200k.

I bet as you say it is fluid maintenance as well as waiting for it to hit operating temp before hammering on these, I see so many people just jump in and beat on cold cars. Engine oil on my daily commute has not reached 200F after driving 10 miles so I am sure rear gear lube is still not up to temp by then either.

 

I can't hear anything over the noise from the damn tires!

 

bikerjim,
I just cant see it being a lube issue at such low mileage on these cars. 30k miles? 57k miles? Not unless they were racing LeMans & getting the Diff. lube overheated or drag racing the cars straight from the dealership or putting the cars through some 24 hour endurance in the Mojave desert in the middle of summer. You have some good ideas to look at though. The Pinion nut and crush washer, but since this was the "New" Vette, I'm not sure they even have these items. (I have alot to learn about C5 Vettes.) I havent looked at the C6 forums to see if this issue carried over to the newer Vettes.
It just seems that this was a weak link in some C5 Vettes.

 

There isn't a pinion nut in the conventional sense. Remember that the drive output shaft from the trans passes through the pinion itself.

I don't have a photo handy.

The ring gear in a C5 is small. 7.625" I believe. In solid axle car terms, it's a popcorn fart. Barely bigger than a Vega. It is pretty beefy for it's size though. The C6 is much larger....GM wised up.

It is possible to "tweak" the gear teeth with judicious amounts of power applied. It probably only takes a few tenths of a thou to make the diff that once was quiet start to make noise.
Ditto for the case which is aluminum. If it tweaked a tiny amount, same thing can happen.

I set up and broke in the 12 bolt in my Nova. it was dead quiet, until 2 trips to the dragstrip. Then it began to howl. I asked Richmond what the deal was. They told me i bent the teeth, and not to worry about it. it has never changed, after several hundred high nine second runs.
I put redline heavy duty shockproof gear oil in it, that helped a bit.....

If it isn't getting worse, just turn the stereo up a bit, or get a louder axle back. It won't fail as others have noted.

BTW, I bet the auto tran diffs fare better. I bought a 3.42 from a coupe and it had 140K miles on it........I was pretty green here.....and it takes dead smooth new pavement to hear just a tad bit of whine. The seller told he maintained it religiously. When I took it apart for the posi and shaft upgrade, it was near perfect inside. Only a little fuzz on the magnet. They are actually quite fun to work on!

Finally, if you can't stand it, and want it rebuilt, I suggest Rick here, or RPM. These take special tools and experience to do correctly.

Ron

 

Whinning generally is the ring and pinion gears just eating each other up. I would try and get a flexible magnet in the fill hole and see if there is any metal debris in the case.


Also, check to make sure it's not a rear hub noise.

 

Sorry to wake up an old thread here but my '01 Z06 is doing this.
Its more annoying than anything and only on part throttle at 60mph and above. Seems non existant at 80+
Tried changing oil to 75/140w and not much difference. Cant say how long its been there because the radio mostly covers it.

BUT what I really want to know is how long have I got left before it goes BANG. I can live with it and don't want to tear into a stock car for no reason. My 5th Gen F body does it and its gonna stay that way !!

Do these things occur and stay stable at 58000 miles or deteriorate ???