I've never come across this before, but there's a first time for everything.

I bought what was purported to be a NEW OE GM geat set. It arrived in an AAM box (although I think Motive is the manufacturer). When I took them out to inspect, I can see what appears to be a subtle contact pattern on both the ring and pinion gears. Also, the pinion's shaft appears to be scored, as if a bearing has been pressed on and off.

Take a look at the following.









I've never bought a new ring & pinion set that wasn't absolutely pristine as far as all the surfaces of the faces on the teeth. I've never heard of running in a set of aftermarket gears. These can't possibly be new, can they?

 

They look new to me, The gears are run to match before hardening,that's why you see a faint pattern, If they were used ,they will be very shinny in the teeth area. And plus,To me ,the pinion gear has never had a bearing installed on it.check to see if the pinion nut has been installed, if it has the threads will be shinny and check the ring gear threads and see if there been any bolts installed The black color is a coating to prevent rust. Before installing the pinion bearing take like a scotch brite pad and clean the black resado off. If the pinion depth is not installed correctly the gear will wine. Best to buy a pinion depth tool ,and start with the pinion shim that's on the stock pinion that in your car.Then add or take out shims to achieve the right depth. Most aftermarket gears have the pinion depth engraved on the face of the pinion gear. Good luck...

 

if Motive is the manufacturer then their part number will be engraved around the perimeter of the ring gear.

 

Well, they certainly aren't shiny like the other used sets I have around here. I've just never seen (or bothered to notice) such a pronounced pattern on a new set before.

The threads look unmolested, so I'm guessing I can proceed as with a new set.

Thanks for the input.

 

When I put in my new Motive+ 4:30 gears, the ware pattern had a yellowish tint to it, witch seemed odd to me , But I guess thats from the heat treatment process. I believe Motive & Strange gears are a five cut gear unlike Richmond gears witch is a three cut gear ,witch is known to be noisier in most cases or just harder to setup

 

After staring at this for a while, I can believe that this is a lapped set.

I think what was confusing me was that I had in my head that this was going to be a 5-cut set, so the faint, slanted pattern gave me some cause for concern (as I get on in years, I am super-sensitive to noise!). I'd have to mic the teeth to be sure, but the ring gear teeth look to be the same height, heel to toe, which I think indicates a 2-cut gear. That could explain the slant in the lapping pattern. Good thing, I would have fought forever to get a square drive pattern on this thing!

 

AAM's are 2 cut, thus the slanted pattern as you noticed. It should be a nice quiet set.

 

Definately a new gear set. It does not appear to be an AAM gear though, unless it is an old stock gear. The pinion shaft is typically cut for an ABS ring for cars like the Caprice and such. What ratio is it and where did you buy it? Any numbers stamped on the ring gear?

Jeff

 

Not AAM? Hmmm... well, you've seen an s-load more of these than I ever have, so I would defer to your judgement.

They are 4.10s, checked: 41 teeth on the ring, 10 teeth on the pinion. There are a pair of letters/numbers on the ring gear; 00331 over the top of 0PXR. They are right next to a 2-D barcode. They all appear to be dot-matrix, laser-scribed.

I have measured the ring gear tooth height (root to crown) in several different spots from heel to toe. They all look to be coming in around 0.312" +/- 0.003", with the variance more to do with my measurment error than with actual tolerances. This would indicate a 2-cut gear, would it not? Is there another brand aside from AAM delivering 2-cuts?

I know that boxes generally mean nothing. Nevertheless, here's a terrible image of the label on the box that arrived with the gears. Included inside was the alert sheet (which I obviously discounted, at first) for the 2-cut gear setup.



Yes, there are labels over labels, but primarily a re-badge to 26014585 to be consistent with GM's part numbering system.

Do you still suspect non-AAM?

 

They now use that method on the diff covers as well, no more tags.

 

AAM makes the gears for GM vehicles aswell as the whole rear end assembalies and AAM is the manufacturer, bought my gears thru SLP and they arrived in a AAM box aswell with a slight wear pattern most likely due to the matching between the ring and pinion gears before being hardened and cured, I do believe but not 100%!

 

Exactly what my 'new' GM gears looked like.

That's Normal.