Hi all. I have a 4X2 F-150, auto 4r70w trans with the 4.6. I am experiencing a heavy vibration at highway speeds. At low speeds, the truck gives me a hopping feeling when driving around town. Also, truck has an instant, but brief jerk or shudder problem when accelarating from a standtill.
I now have a sqeak comming from the rear of the truck. I was debating whether its the u-joints or just a brake adjustment is needed. The sqeak seems to stop when I apply the breaks. I was hoping that somone might be able to inform me of more symptoms of a u-joint on its way out. considering the vibration problems I'm having I am leaning toward bad u-joint over a needed brake adjustment.
I have another thread in this forum asking if anyone had more information on ways to change the driveshaft angle as a possible solution to my problem. I'm pretty well convienced that my problem somehow lies in driveshaft/yoke. I was wondering if the driveshaft could become slightly warped over time. Im trying to do as much research as possible on the subject, but am still unsure exactly how my problems are related and what can be done as a permanent fix. Any feedback would be greatly appreciated. Thanks - Trevor

 

Grab the driveshaft and try to move it. If the joints are good you will have almost no movement whatsoever.

 

Thanks Powerstroke, Ill give that a try.

 

vtford,
Sounds like mine and it was also a U-joint. Problem is it was not loose at all. On the truck I could not tell it was bad but when I took it off the u-joint was dry and sticking when I moved it. The race was also groved by the dry needle bearings. I replaced both with greasable units and problem fixed. It is the cheepest way to rule out other problems.

 

WLF, I appreciate the info. Sounds like I might have a similar problem. I plan on really getting to the bottom of this problem of mine very soon. I will be sure to post anything interresting or useful that I find. Thanks for the input.