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While I'm still messing with my sleepy Packard I happened to be under it and was messing with the drive shaft and found there is about a 1/4 inch to 3/8 of an inch of play when turning the drive shaft before you feel it hit the ring gear. Were they really that sloppy? This car has around 47k miles and I can see that the rear end was leaking due to the amount of gunk on the bottom of it. I'm hoping that the gears aren't trashed but if they are where would be a good place to get another ring and pinion?

That's way to much play. Typical backlash between a pinion and ring wear is around .006 to .010".

Ebay is one place to check for a replacement.

You may want to take the diff. cover off to check to make sure the ring gear carrier bearings are not bad, before buying another gear set.

This would also give you a chance to visually inspect both the pinion and ring gear, before purchasing another gear set.

The pinion adjustment could also be way off, resulting in excessive backlash.

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  Packard Ring and Pinion.jpg (46.25 KB)

First of all what car do you even have?

About .006 is typical on many. 1/4" is insane. I would remove the diff and do a thorough inspection. Who knows what is wrong with it.

As long as all the components are in good condition, you can throw it back together following the service manual. 47k is really not much. I replaced the carrier bearings in my Clipper at 93k.

Is the play you feel at the ring gear or is it the sum total with the side gears in the diff itself and the fit of the axles in the side gears? The play to the ring gear would be rather hard to feel what with the preload on the pinion bearings and the drag of the seal. The total play is of course no trouble to feel and could easily be 1/4".

Good point, the rear axle has some decent play as a whole.

Another note is if you have the car off but in gear with the rear axle in the air, and spin one tire, it probably won't feel like it's spinning over "smoothly", like it probably will slightly "clunk clunk clunk". The gears were not perfect, so that's normal.

I've had a lot of cars that would show 1/4" free play or more when rotating the pinion shaft through the play by hand. (Wheels on ground) They all worked fine. Axial play at the pinion shaft will often cause gear whine, seal leakage, and driveshaft vibration. To get some idea of the ring/pinion backlash, I think you'd need to remove the cover and rotate the pinion shaft by hand with the ring gear blocked from turning. Most likely, backlash will diminish when the axle is at operating temperature, and attempting to adjust worn-in gears may lead to trouble. I have had success adjusting axial play out of pinion shaft bearings. Doing so eliminated driveshaft vibration and pinion seal leakage.