I had a problem with my rear main seal which disintegrated and ended up at the oil pickup screen. I was lucky to catch it in time before any engine damage. Anyway, I replaced the seal with a rubber main seal for a Chrysler slant six engine (if I remember correctly). It was not so difficult to to with engine in the car and has been dry since.

Could be something to consider.

Thank you all for commenting. I realize now that the bearing clearance can be in play as both axles have the same amount of run-out. As you mention that now is a good time to service the bearings, so I will be taking the shafts out anyway and might as well measure them on the bench to investigate it further.

I will let you know how it goes. Thank you all!

Hi!
I am a long-time reader but first time poster.

I purchased my dream car a 1947 Packard Custom Super 4dr a few years ago and been working with it ever since. I have made good progress with it and driven it a lot this summer but have had a heavy vibration at certain speeds that puzzled me until my father driving behind me noticed the rear wheels bouncing up and down and to the sides.

We pulled the rear wheels which were OK and balanced, measured the drums which were heavily bent in all directions (a couple of mm or 0.1") and must be the source of the heavy vibration, finally found! I guess a lot of violence was used to get the drums off earlier. I have now ordered reconditioned drums from Kanter which will cure this problem.

I then pulled the drums to measure the runout of the axle shaft which came in to about 0.07 mm or 0.003" at the end of the tapered part. Can someone please advise me here if this is within spec or if I need to take care of it? I see no guidance in the shop manual and want this perfect. If outside of spec then my plan would be to pull the shafts and see if it possible to straighten them. What do you think?

Thank you very much for this site. It has helped me enormously with getting the car to work!

/Magnus