56 drive shaft

["Mike & Christine Trettin" <mtrettin@xxxxxxxxxxxxxxx>]

> Now, here's the rub.  The obvious drive shaft vibration and associated
noises
> are gone, indicating that the shaft indeed wanted attention.  But there is
> still a very pronounced vibration on acceleration at about 20 to 25 mph.
It
> mostly goes away at higher speeds, but is still noticeable.  I thought
> perhaps the problem was with the engine somehow, but when the tranny is
put
> into neutral at speed, there is no change in the frequency of the
vibration.
> Could it be the wheels, or the rear axle, or even the differential?  I
notice
> a pronounced "clank" when put into gear, both forward and reverse.  Since
the
> drive shaft has just been refurbished, I rule out that angle.  What could
be
> the source of my continued "vibra-bed" on wheels?

John,

Even though the driveshaft has been rebuilt recently, I wouldn't assume that
the U-joint angles are correct.  You might read up on the subject from a
Chrysler Master Service Conference booklet we've posted on the club's
website here:
http://www.imperialclub.com/Repair/Lit/Master/114/index.htm

In fact, on Page 10, Chrysler states, "When testing an Imperial (two-piece
shaft), experience indicates that a vibration between 15 and 20 m.p.h. is
apt to be caused by prop shaft misalignment (incorrect working angle),
rather than shaft unbalance.  But if the vibration comes in at speeds above
28 m.p.h., chances are its caused by an unbalanced condition."

Here's the direct link to that page:
http://www.imperialclub.com/Repair/Lit/Master/114/page10.htm

Best of Luck!

Mike Trettin
1956 Imperial Sedan, Turquoise