ring and pinion question

[JoeGrapes]

I have a 489 case 3.91 sure-grip center section. When I put it in my Cuda it was whinning, smooth but noisy. The teeth look great with no wear or chips. So I'm going to re-set it up with new bearings. The pinion is marked with a "#15" on top and a " 4" on the bottom. No plus or minus sign, so I'm guessing the 4 is a plus. There was a .033 shim on the pinion. I believe the distance from the back of the pinion to the axle centerline ie 4.344. I'm a machinist and have access to all the measuring tools I need. If I measure that distance and add the shims I need to get 4.344 what do I need the 4 on the pinion for? Do I still need to subtract .004 from the amount of shims I have to get to the 4.344 Dim? Just a little confused. Thanks

[pishta]

My 3.91 741 was whining also, so I thought I could reset the measurements and replace the pinion bearings. I did all that, everything was dead nuts on, good pattern, new bearings, preload, etc. Still whining, worn gears, no fix, need new gears..

[John Kunkel]

The chances of quieting a noisy set of gears by resetting them is nil. Once they've been run any distance, the wear pattern is set.
Every set of noisy gears that I've seen had a perfect appearing wear pattern.
The nominal 4.334" dimension is from the axle centerline to the FRONT face of the pinion (where the shim goes). This dimension is only a starting point since the final setup is determined by checking the contact pattern.

[JoeGrapes]

I had in the back of my mind I was going to have to replace the gears. I guess I thought maybe........? But now I know what I have to do. John, I got my back and my front mixed up,lol. But I do know which end to take the measurment from. Thanks for all the help everyone.