Packard Forum Index » V-8 (1955-56)

My 55 400 has very noticeable vibration between 30 and 40 MPH. It doesn't vibrate when coasting down hill in neutral. That leads me to believe that the torque converter is not properly balanced. The transmission was rebuilt a few hundred miles ago. It did not vibrate then.

The rear U joint was replaced, needlessly as it turned out. I don't' know how to check the front one, and word on the forum is that new ones are unavailable.

Can someone tell me how to check the torque converter for proper balance and how to correct it if out of balance?
Or where to send it to be checked and corrected if necessary?
Or thoughts on what else might be causing the problem?

Thanks in advance for any help.

Bernardi in Pittsburgh

Perhaps the person who disassembled the converter failed to to scribe the position of the converter sections before hand, see Page 14 in the Ultramatic section of the 55/56 shop manual. The entire converter assembly is balanced as a unit via welded lugs to the direct drive clutch housing. I suspect that a good full-service automatic transmission shop may have the equipment to rebalance it.

Yes, the front universal (ball & trunnion type) for the senior cars has been pretty much unavailable for some time. Properly maintained it should be good for a very long time but if a careful inspection shows it's worn beyond usefulness, browse this site (or perhaps someone will look up the post and give you a link) and you'll find information about making a new drive shaft with a forward splined slip yoke and conventional front universal. Any good driveshaft shop should be equipped to do that job.

Also, though you probably can't find a new complete joint assembly you may be able to find a repair kit for it which includes new balls and needle bearings, and perhaps the cross pin. If the housing is not worn, this may be satisfactory. Worn housings can also be returned to original specs but it's an expensive operation, perhaps more expensive than having a replacement driveshaft made. But if the rubber boot was intact and there was plenty of grease in the joint, I'd say there is a good chance the joint is OK - mine was OK at 93,000 miles.

Thank you, Owen. I hadn't thought of a modern transmission shop being able to work on a Packard converter. I'll look around.

The front joint has about 70,000 miles of use.

You can check your convertor balance by merely revving the engine in neutral to about 2000 rpm to simulate a road speed of 40-50.

I would vote for a problem with the front joint. Sometimes you can find a new "sweet spot" on those ball and trunnion joints by loosening the bottom side bolts on all 3 motor mounts and shifting the whole engine/tranny to a different position.

And if you need to consider changing the front joint to modern slip type here is what is involved and a place another poster used and said did a decent job.driveshaftspecialist.com/Left-Column/Antique-Classics.html

Howard, thanks for looking that up, I've bookmarked that as no doubt this will come up more and more in the future as the original B&T joints reach the end of their lives.

Image below from the website noted by Howard.

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One should never, ever separate the two halves of the Ultramatic torque converter-especially for a V8-without first making an alignment mark along the side of the mating flange. I simply use a fine chisel and give it a whack on the side prior to disassembly. This way I know the exact position where the halves were mated at the factory.

Otherwise you will never, ever get this factory-balanced unit back into balance on your own and yes, it will indeed likely vibrate. It CAN bolt together in any degree of 360 where the bolt holes align, but it will vibrate unless put back into the exact position where the factory made it.

This is the first basic step anyone should perform prior to working on these transmissions. Most folks working on these Ultramatics are unaware of this simple procedure.