mysterious vibrations and humming?

[Elwood blues]

My truck has been loud lately, at first i thought it was just tire noise so i rotated my tires thinking they might be wearing funny. now i feel like its not tire noise at all. i hear a humming and feel a vibrations around 40 mph and on the highway occasionally a loud humming as well. not sure what it might be i was thinking maybe bad u-joints as a can twist my front driveshaft but not my rear one. and when i hear the humming/vibrations around 40 mph it seems like it is coming up or around the center line of the car ( which made me think the check the driveshaft) or on the highway it usually comes more from the back of the car. Anyone have any ideas?

 

[chefduane]

Same thing happened to me. Bad u-joints. I replaced both front and back just to be safe. Get the car up to speed (50mph or so) and drop it into neutral and coast. Then rev the engine. If there is no similar sound then it has to be drivetrain related. If the sound persists, then it's probably engine related.

Edit: ... or maybe bearing related.

 

[Elwood blues]

well there is still the play in the driveshaft but it could also be a rear wheel bearing

 

[Elwood blues]

i did slide into a curb a few years back and i ended up knocking the tire off the bead and cracking the rim. i did just notice a little while back the the hub wobbles when you spin it. i know i need to fix that but not sure what needs replacing also if it is the problem why is it just happening now?

 

[Elwood blues]

k so i replaced the axle shaft and the wheel bearing for it and while it does ride a little smoother the humming has not gone away. this leads me to think its something along the driveline (u-joints, transmission, driveshaft). it starts around 30's with a small hum and gets the loudest and most noticeable around 37/38 mph.

 

[XLTrunner]

If that axle shaft was wobbling within the hub, I'd be focusing on possible damage to the rear pinion brgs/gears. I'v had my truck for 3 yrs and had a noise much like you describe and couldn't place exactly where it was coming from. It steadily got worse. Turned out the pinion brgs were worn and gears were showing an uneven wear. Replaced them and never knew my truck could run so quietly. I've been told this is a common problem with these trucks.

 

[SWIGIN]

My daughter had the same noise in here Explorer and after a few hundred bucks and 2 mechanics she brought it to dear old Dad to install new u joints.....no more sound.

 

[Elwood blues]

It wasn't wobbling within the hub I bent the hub itself causing the tire to wobble. But I hope it's not my rear diff or I taking it back because I just had it rebuilt last year