History.. I installed these gears(4.56 Richmond), about 10 years ago. Pattern good, BL was at .010". Over the years of street and race driving, there was no noise. Gradually, starting about 2 years ago I started noticing a gear whine/whorrling noise when coasting or maintaining speeds on the street. With open headers, you really can't hear any noise at all...On the street, the noise is like an on/off whine when maintaining a speed, any speed... When on power there is no noise at all. Quite as a mouse. I think I know what is going on, but wanted confirmation. SO, what do you professionals think is going on?? By the way, all bearings were replaced when installed and the rear has never been run low on fluid..

Pull the cover and check the backlash in multiple places now
It sounds like gear wear to me

No pro but the pro's told me to start WAY tighter on the back lash as it loosens up till it sets and I set my 8 3/4 up w/about .005-.006 and it's nice n quiet..........

I can tell you when mine was on the verge of of ripping the teeth out. The .007" backlash went to Zero. Teeth were bent over.
Doug

Ten years of whoopin with a big stick may be taking it's toll
I just changed the gears in my Dana and the teeth had a shine and they were starting to get sharp on the edges.
I know it's not much fun to get the backlash perfect but I like to get mine around .008
Someday I will replace it with an S-60 with the threaded adjusters and life will be easier every 10 years or so

Gus

I'm hardly a pro, but the last time I had a rear-gear whine, it was the pinion depth being off. Even correcting that, the wear was sufficient you couldn't get a nice pattern, needed new R&P. It was a used 489 8.75 that had supposedly gone on like that for about 500 miles. Added one of Dr Diff's crush sleeve eliminators.

If it was quiet, and then it wasn't, something moved or something wore out. Probably going to need a new gear set and whatever else is worn out. Can't (I won't) put a crush sleeve in any kind of race/performance application rear. They can move, then you have an issue.

Never heard of that.

Thanks for the replies.. Let me see if I can address some of them. First, I was told by the manufacturer back then, that you need to lean toward more back lash. They said a cushion of fluid is needed between the teeth. That is why I set the gears up with a B/L that was somewhat in the middle of the .008"-.012" that was called for.
Second, There is no noise at all when on power. Just when I'm coasting or more so when trying to maintain speed. It is louder when maintaining speeds. Coasting is quieter, but still there. Maintaining speed noise is more of an on/off type noise (whine/whorl). Coasting is a gear whine noise only.
Third, I agree something has worn or moved. I will pull the cover today and inspect. I'm hoping to not have to change gears. But if I have to, I'm wanting to wait til this winter to do it as changing gears in a Dana isn't as easy as a drop out rear. I'm also thinking that because it doesn't make noise on the power side that it can't be too serious at this time.Also, what about setting up a gear set that has been used? I've never had any luck doing that, but have any of you??? What do you guys think???

I would say that the pinion bearing has started to go opening the lash gap. I opened up mine one time and the end tips if the pinion gears flowed out.

This came from a couple of high end racers not street stuff and so far it seems to be working although I haven't pulled it apart to check things out and have no plans to do so for another 15 years..........

Pepe Estrada of Pepe rear ends in L.A. CA said the same thing to me years ago especially on 8 3/4
Same thing from the guys who worked for Richmond installing gears at all of the NHRA major races back in the 1980s They all said to installed them with minimum backlash, even tighter than the minimum etched on the ring gears

Alrighty then.. Just got done putting things back together. Here's what I found.
1. B/L was wide. .013" checking in different areas.
2. Gear pattern has shifted. Now very low on the drive side and very high on the coast side.
3. I hear (even with my bad hearing) a subtle clickity/clack from deep inside the housing, but only in one area of rotation.

My thoughts are that, like rowin4 has suggested, a pinion bearing is starting to go.
I'm going to try and nurse it through the summer. Will install a new gear set this winter. Wish me luck!!!!

68Lar...the only time I've had a noise from a Dana was on my truck. It developed a whine on deceleration. Pinion bearings were worn and had a lot of slop in it. New bearings and all is good again.

So, how long did you drive it before changing the bearings?

My concerns now are two:
1. Will setting up a used set of gears work?
2. No matter what, I would have to pull the entire rear end to either, change pinion bearings or, install a new set of gears. If I got to pull it, I'm going to put a new set of gears in. A lot of work one way or another..I don't have a car lift, and the center section of a Dana is pretty heavy. Working off the flood just don't cut it...but it is how I do things..

Noticed the noise coming home from the track one night towing the car/trailer. I probably drove it another month or so (unloaded). I usually have to drive it to work one or two days a week.
I did it all on the floor (I also don't have a lift) and reused my old gearset. They looked good. Got lucky and everything checked good just reusing the original shims.

BTW...this was 3 years and 30k+ miles ago.

Just put a set of used gears back in the van, 4.10, got the pattern in the middle and bl +_.005. Pretty quite except where I ran the disc over 3-4 teeth that was rust-pitted (water in the other housing) sounds like train on a track, but only up to about 20 mph. I can live with it till I find a better set. The pinion I took out had the teeth rounded over along the spine, I'm thinking pinion bearing went out from a previous owner and they just installed new bearings.

Well, I decided to just replace the pinion bearings. Taking everything apart, guess what I found??? Yep!!! bad axle bearing on driver side. Soo, I'm changing those, along with the pinion bearings and I hope that I can reset the gear pattern without any problems..I will go to the tight side of the B/L this time..Thanks guys for sharing your knowledge. FYI, I had thought all along that it was a pinion bearing. Didn't figure on axle bearings????

Again, no pro but I've been told that w/used gears it's better to put em back as close to where you started than to tighten em up and it kinda makes sense.............

^^^ I had to go .005 deeper to get the pattern right, and that was using the Miller micro gauge.
Had me scratching my head