shimmy under acceleration

[fiftyfeetup]

i have a shimmy which only occurs when i am accelerating/maintaining speed with the gas. it does not occur when coasting or reving the engine in neutral or park. its frequency is very rapid and increases with speed. recent changes to the vehicle include rotating my washboard worn front tires to the back and greasing the driveshaft. could this be due to the unevenly worn back tires transferring the shimmy when torque is applied but not when torque is not applied? i have never heard of or seen this before anyone who is knowledgeable and has experienced or heard of this feel free to respond.

 

[Fantasymon]

Hey, I don't know what "shimming" is but this seems similar to my problem that I just posted about loud noising coming from the front of my car or axle. It happens only when Im driving and accelerating a lot.
(Not that this helps you at all)

 

[fiftyfeetup]

shimmy

a shimmy is a rapid shaking or vibration. i have no noise associated with mine. oh, how do you like those rancho rs9000 shocks?

 

[blackbeauty]

my 98 sport does this. it first occured about a month ago, i took it to ford and they said it was the rear u joint on the rear axle. so i replaced both on the drive shaft with napa greasable joints and the problem went away for two days. then i went wheelin and the problem resurfaced. i think the guy who helped me fix the joints dinged the driveshaft with a hammer too much and threw it out of balance. so i hope that helps, maybe u joints.

 

[Fantasymon]

ahh the shocks are alright....I have a pretty rough ride with the little lift and oversized tires....I think the shocks are extended a little too much with the lift but definately better than stock.

 

[fiftyfeetup]

at first i thought that i threw the driveshaft out of balance when i greased it, but i think that it would still occur when coasting if that was the case. the u joints are fine, i just looked at them a few days ago.

 

[ExplorerDMB]

Is this 4wd? You could have a bent half shaft. Balance your wheels also. Greasing a u-joint will not make it unbalanced.

-Drew

EDIT: I just read your signature and noticed that you have the 4" superlift. Did you buy the other front driveshaft or what exactly did you do with the front driveshaft?

 

[lhill58]

If you have not changed the transfer fluid yet I would give that a try this seems to correct the issue for most people. I changed to a synthetic fluid as well.

 

[falls chic]

It could be something as simple as a shifted belt in one of your tires!?? Maybe not so noticable when the tires were the other way around.

 

[Mbrooks420]

Bad tires, or an unbalanced shaft are no emergency.