Packard Forum Index » V-8 (1955-56)

For the last year or so there is a vibration that occurs under acceleration (up to about 40 mph in 'D'rive and 'H'igh). I know that at least one front motor mount is bad (the motor lifts on the driver's side when I rev the engine with the car in drive and my foot on the brake). I understand that this could cause the kind of vibration that I am experiencing. I have new front motor mounts, but haven't installed them yet (my bad). I've also heard that when the problem is broken motor mounts, the vibration usually happens under braking, not acceleration.

With the recent threads on the 'fibrous washer' in the early '56 Twin Ultamatic torque converter being a problem requiring the rebuild of the transmission. My question is, have I gone too long and ruined my transmission beyond repair?

I know that I need to r&r the front motor mounts and if the vibration stops, problem solved and no harm done. But what if ...?

Hard to say on the trans. It is actually a thin metal washer which gave the grief. When it failed the particles or maybe it was excess play which apparently chewed the aluminum vanes. If you did a routine fluid drain and didn't find any tiny metal particles in the oil pan, that would be a good sign.

I won't drive the car until I replace the motor mounts and service the trans (looking for any metal). Thanks for that.
I don't think it would be the u-joints or drive shaft ballance because the vibration would continue all the way thru the acceleration (not fade after 40 mph).

Packard had a problem with vibration around 58-62mph as was discussed in bulletin 56T-10 (corrected version). That issue was apparently caused by the angle of the differential to U joint. In addition to the motor mounts, if something has sagged or deteriorated in the rear axle suspension or mounts I wonder if that could reflect with vibration at the speed you notice.

That is a symptom of imprpoer U-joint working angles.

If the motor mount is broken the working angle is changing.

Howard and Tim,

Interesting and something that I was not aware of. During my TL dramas, I did replace the rear sway bar bushings and the mechanic had some issue with one of the sway bar mounts and ended up cutting and welding the mount back together. I wonder if that, plus the bad motor mounts combined to yield the vibration?

I agree with tim,

the upper u joint, the ball and trunion, if its org, could be worn, I had one that wore a groove, in the machined slot for ball.

and you can get the clipper/ exe,, ball and trunion, dodge uses it, its on the market,, I think it would be ok, the larger ball, was probably for more hp, but, what do you guys think?

Fully agree with Tim about the results of broken/failing mounts. The front motor mounts for the V8s have been available as new reproduction parts for some time; they are relatively inexpensive and are "duck soup" to install so no good reason to batter and abuse your driveline by not replacing them when needed. I suppose you could consider having your old mounts revulcanized but I suspect that will be considerably more expensive than just purchasing new ones outright. I replaced mine some years ago with the Kanter repro parts and fit and function were perfect.

As to the front ball & trunnion universal, the ones for the Senior cars are pretty much extinct so they deserve periodic cleaning and repacking.

my ft mounts, I but bolts in them,, at the time no one was repairing them,

Riki,

Any pictures of what you did on yours?