Hey guys, I have an annoying shake that I feel mostly in my seats. It happens at about 45mph then goes away til about 65mph where it comes back but as a faster shake. I have searched the forums and it looks like it could be anything from driveshaft to tires and then some. The truck is a 2002 w 4.6 4x4 and manual trans. I have checked the u joints, balanced the tires, and lubed the slipyoke on the driveshaft. I had seen on one post where someone recommended removing the driveshaft and driving it in 4x4 to eliminate this as the possible problem. I am tempted to try this but I am concerned that I could damage the truck. I don't have a shake in the steering wheel so I don't think it's a front end thing. Any thoughts or ideas are appreciated.

 

Check your front drive shaft u joints to the transfer case.

 

I had the same thing with my 97, couldn't find a thing until it started to squeak when I started to roll forward. Not knowing your mileage if you have
around 80,000 or more I would replace the u-joints, not that big of job to do that will need to be done at one time or another anyway

 

I have replaced the rear u joints recently and the problem is occurring in 2wd so I don't thinkthe front u joints have anything to do with it. Any other ideas. Again,is it safe to remove the drive shaft and drive in 4wd to see if it is part of the problem.

 

Check your FRONT U joints. Mine felt fine, but were grinding like hell when I got them out of the truck.

Somebody will correct me if I am wrong, but I believe your front driveshaft will still spin when in 2wd.
I can't imagine there would be a complete lack of gear friction that it would stop spinning completely. Especially at highway speeds.

 

You are correct....there is some frictional pull on the front drive shaft.It will spin at highway speeds although it will be slower than the rear.It is enough to cause a vibration.I have had this happen to another truck I had.

 

I checked the front u joints and everything seems fine. I noticed some play in the trans mount. Not sure how much to expect. Also I have seen where people recommend to have the tires road force balanced rather than just the regular balancing. Who does this type of balancing?