Worn out diff cause hwy vibration?
 

Replacing drive shafts but planning next course of action. Have hwy vibration with slightly audible drone about 75mph. Can't tell if noise is mechanical or just everything inside the vehicle hitting a harmonic tone from the vibration. Sounds like i have veey aggressive mud tires but only between 73 to 78mph.

It's possible, but sounds more like a wheel bearing(s)

Hubs crossed my mind but I wasn't sure if they would show symptoms in such a narrow speed range

Easy way to tell hubs, jack it up and give the wheels a shake, also if you can spin the wheel at all, listen for noise. Could it be wheel balancing? I had that happen and it ended up being the front drive shaft on my truck.

How old are your tires? Old stiff sidewall tires can cause high speed vibrations, even if balanced recently, also. Sometimes the tires are older than most, because these rovers get driven less than normal. Any tire over six years old should be replaced, even if tread is good.

​​​​​​​Wheel bearings would be another go to area, especially...if they are original. Cheap and easy to replace, and why not...they are probably fifteen years old.

Usually, if you have any type of excessive wear in the axle...ring and pinion...it will give off a high pitch whining noise at speed or while letting off the gas pedal. You could drain fluid and look for excessive material in drain pan or on magnet plug. Mind you, some light/fine material stuck to the plug is normal on an axle that hasn't had a fluid change recently. Maybe upgrade to high mileage axle fluid, see if that changes the noise at all.

​​​​​​​ Brian.

Also...add vehicle information to your signature line...it helps to know what year vehicle were talking about.

​​​​​​​ Brian.

​​​​​​​Attempted sig update

I have a '03 D2. It also had a vibration in a limited speed band. My D2 started as a non driving project, and as a part of the build we did new wheels n tires, drive shafts, lift... It always had an annoying vibration, turned out to be the front drive shaft. Put an other new one in and vibration gone. I've also been through a couple hubs starting to fail, they did not cause a specific vibration.

I should add, the vibration was there with the original center diff and still there after we swapped it to a locking diff. I've not touched the front or rear diffs other than to change their oil.