Excursion - rear drive shaft rumble

[cleah]

I have a 2003 Ltd. It developed a rumble, similar to that experienced when driving on the rumble strips at the side of the freeway, only less severe. It only occurred at two speeds (35-45 mph and 65-75 mph). As the whole frame shook, without shaking the steering wheel in a rotational manner, it was difficult to locate the cause. After having all four wheels re-balanced, checking for front wheel bearing and steering play, fitting new fuel filters (suspected engine starvation), checking the air filter (suspected engine suffocating), checking front and rear diff. oils, transfer case oil and transmission oil, and checking front and rear drive shaft play (with the wheels on the ground), the rumble was still there.

That was when I sought professional advice at a Ford Dealership, making sure they had a crusty old engineer of the type who can sit in the car for a few miles, listen to the sounds and feel the feedback through his body, then make an accurate diagnosis based on years of experience.

Charlie at Brent Brown Ford in Provo was just that. It took a couple of attempts, including temporary tire changes to eliminate tires from the problem. After a few hours, he discovered that the U/J between the rear end of the rear drive shaft and the rear differential had suffered siezure of one of its four needle roller bearings, and a second was well on its way out. The rollers are very fine and there are a lot of them. All of the rollers had left one bearing, and about half from another; the remaining half being mangled and jammed.

After replacement of the u/j, the problem was less severe, but never-the-less still there. After putting the car on the ramp and running it at 65 mph, he was able to observe the rear drive shaft oscillating and deduced that the siezed u/j had bent the shaft. A new shaft would be $492 + $50 fitting and then tax. However, BW Drivelines of Provo were able to straighten and balance it for $80. This seems to have solved the problem.