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Hi guys, another question.. Had the Packard out yesterday. Under load through all 3 gears, it sounds good. Under no load, or coasting, differential has a heavy vibration and gear sounding chatter. It also causes slight drag on the car when it chatters. Was told by previous owner duff was rebuilt. Any ideals on what could be going on?
Just pulled the drive shaft off and it has one eighth to three sixteenth play in and out at the universal joint flang.

If you mean there is in-and-out movement or free play in the pinion shaft, then you have significant problems - if it has been that way for long the pinion bearings and perhaps even the ring and pinion gears may be damaged.

I suggest you read the shop manual, not only should the pinion shaft have no free play, it should actually have a preload!! Initially this would have been established by tightening the pinion nut and partially collapsing the crush sleeve sufficient to attain the specified preload.

At this point my recommendation would be to disassemble the differential to see how much damage has been done.

I'm weighing in here, not because I know very much, but because I just reinstalled my drive shaft and have 'fresh' recollections of the process. The in/out play you refer to - is it end-play in the diff-yoke or the drive shaft-end? My '39 has about that much (spring loaded) play in front yoke of the drive shaft and I had to compress it to get the universal joint seated into the tranny yoke. As Dave says, if it is pinion play, it portends a significant rear-end issue. I know at some point, I am going to have to deal with a rear-end rebuild on my car, just due to it's age and wear, but right now, it is not leaking or making any obnoxious noises, so I am, for better or worse, leaving it be. The thought of an overhaul on it gives me chest pains! And Don, re your 'tilt',am I to understand that the angle the diff-yoke meets the drive shaft is not a straight line?? How much off true is it?? I would think it would be very hard on U-joints if it is in any way excessive!?!?!

Chris, I removed my question from this post (I didn't want to hijack it!) and created one of its own along with a photo, which you can see here. To answer your question, the axle housing was tilted to match so the driveshaft was still inline but lower.

I bought the car in good faith being told the diff was rebuilt. It has not been on the road until yesterday when I discovered this problem. I'm understanding from this that the pinion shaft can be adjusted...can the pinion shaft nut be adjusted to eliminate the 1/8th end play?
Is it possible the differential was improperly reassembled and could result in this 1/8th end play?

It just guesswork unless you're willing to go thru the procedure to properly establish the preload on the pinion bearings. To repeat, read the procedure in the shop manual.

Yes, tightening the nut will begin the process of eliminating the free play and will then begin creating the preload. The question becomes, how do I know how much to tighten it unless I go thru the procedure to measure the preload?

Once the crush sleeve has been crushed, no adjustment is possible so the bests recourse, once you read the manual, is to remove it for proper inspection. If the gears have already been damaged, no amount of tightening is going to fix it.

Thanks everyone for your help. I have taken her to an "old fart mechanic" since I'm to old for chest pains. Will keep you posted.....

Well, I couldn't sleep so went out and tightened the 1 1/4 inch pinion nut one full turn. That took out all end play and she runs great. Had to make thin wall socket to fit in universal joint flang. You Packard folks are the greatest. Thanks for all your help.

Congrats, just what I was going to suggest. Now take a punch and stake the nut to the shaft for long term happiness.