HELP!!!! Front Driveshaft issues!!

[Ryan21288]

I just recently picked up a 97 V8 Explorer for $800. It has 159k on it. When I picked it up it needed a front driveshaft. There was none installed but came with a new one. It ended up being a for a v6 and did not fit. Finally I found a used one for a v8. Picked it up and put a new U joint on it. I installed it today and went for a test drive. The truck feels much different now. It almost feels like there is more resisitance in the drivetrain and on full lock it feels like its constantly in 4wd. However the 4wd seems to be working as punching it in sand produces minimal wheel spin and without it would have smoked the rear tires all day long. The problem im having is a noise from the front of the truck when driving that gets louder the faster you go. It sounds like a whirring or humming noise. Also when you get to 50-60mph there is a constant vibration like your hitting the rumble strip on the side of the road just not as bad. Could this be a bad driveshaft or possibly low fluid in the diff or transfer case? Also all four tires are the same size and have aprox the same amount of tread but are slightly different fronts are goodyear wrangler rt/s rears are goodyear wrangler radials. Please help im leaving for vermont tomorrow and need to know what to do!

 

[RomeovilleIL]

You have too many variables to give a definite answer without testing.

A few of observations:

Is your V8 an XLT with the 4WD switch or an AWD with no switch on the radio bezel? The majority of V8's are AWD which by design IS constantly in 4wd so yes it feels that way in a full lock turn.

All of the tires have to be extremely close in size on the AWD. The design is essentially a limited slip differential between the left/right rear tires & front/rear axles at the same time. (Front left/right are open so the truck can turn). If tires are different sizes the system locks and parts wear.

You bought a used prop shaft and replaced the u-joint, but not the CV. The CV should turn easily and smoothly by hand with no binding before you put it on the truck. Any stickiness means it is shot and needs replacement. A bad CV will definitely cause the type of noise and vibration you describe.

Your issue could be from all kinds of causes, but considering someone took the old drive shaft off it may have been the culprit assuming you did not have any vibration prior to replacing it. If you cannot fix it before the trip, take the shaft out and drive without to avoid any potential major damage.