Jim Grant's Tech Tips
Plymouth Voyager, Wheel Wobble
Q: One of the problems your readers had
submitted struck a nerve. The problem was for information on wheel wobble
from their ‘88 Caravan. He was told by techs it was warped rims. I also
have this type of problem on my ‘91 Voyager and have even met another
with a ‘93 Voyager with the same wobble as mine. It seems that when I
accelerate I feel a wobble which seems to be from the rear since I can
feel it in the seat and floor. The wobble goes away around 20 MPH and
doesn’t come back until I stop and accelerate again. I too have checked
for rim and tire damage. I have also checked powertrain mounts, rear bearings
and brakes. Could we all just have bent rims or is there a solution to
this problem? Please help us.
shop was beginning to see a plague of Chrysler/Dodge/Plymouth mini van
wobble problems. When accelerating these vehicles had varying degrees
of wobble. In one case, using the Chrysler (star) hood ornament as a cross
hair to sight the road line, the star orbited like a drunken sharp shooter.
A person with sensitivity to motion would become ill riding in this vehicle.
The vehicle was moving left to right on its own in a manner that one would
think that either the rim was bent or a belt in the tire was failing.
This condition was a progressive failure barely detectable in the early
stages yet it propagated into a most bazaar wobble . To save you all the
agonizing, the root cause was found to be a failed driver’s side plunge
joint. The inner joint on a front wheel drive vehicle’s axle is called
a plunge joint. There is a lot of geometry going on in a vehicle’s front
suspension, which requires the ability of the front drive axles to change
length. The plunge joint allows for this. Removal and inspection of the
plunge joint found that the internal spring that loads the plunge joint
had failed and the joint was wearing the bearing surfaces. The fix was
a replacement plunge joint.
when an inner plunge joint is failing in a vehicle there will be a high
speed shake that develops. This is because the axle will be spinning off
center. The driver’s axle in this application is short, it does not have
sufficient rotating mass to develop the high speed shake as the much longer
axle going to the right side. What makes diagnosing this condition interesting
is that the wheels of the vehicle do not wobble. It is the body of the
vehicle that is moving. The tire has the weight of the vehicle forcing
it to hold its line in the road. The uneven wear in the plunge joint pushes
on the axle and transmission. The tires will hold a straight line and
push against the axle which in turn pushes back on the transmission which
moves the body of the vehicle. Brings a whole new meaning to a boat ride.