droning noise at 75-80 mph

I've got a weird low sounding droning noise that I can slightly feel on the floorboard at 75-80 mph on an '02 Disco II SE7. The tires are good...not chopped and are balanced. And it still makes the noise after I have the tires rotated, so I've ruled out the tires. I just replaced the front drive shaft thinking that would solve it and it didn't. I've had the rubber connector on the rear driveshaft checked and it's in good shape. I don't drive above 80 mph, but the other day I noticed it stops making the noise when I get above 80 and it doesn't make the noise below 76/77 mph. Someone could simply say to not drive at that speed, but now that I've found the noise I want to fix it. I felt like I've checked everything for a vibration noise. Could it be a wheel hub? Has anyone ever heard of anything like this or does anyone have some suggestions? Thanks.

Ryan

I'd just slow down.:thumb-up:

TNDisco2 - I had a simlar problem with an F350 and hte turbo. THe droning would only occur at a certain rpm. Ultimately the turbo design was replaced as it vibrated through the floor board. Apparently the harmonic vibration of the engine (diesel 6.0) was amplified or transfered through the turbo prdestal. I realize this is not the same vehicle. However, principle holding true I would check engine and transmission mounts to be tight and that bumpers are in place to absord vibration. You might also verifiy if it is a certain rpm rather than a mph issue. If it is a driveline vibration the vibration should duplicate itself at double increments (ex 40 mph and 80 mph should give vibration). You might also check all the plastic hanging on the front bumper to make sure its not vibrating with wind speed (kinda like air coming out of a ballon when stretching the mouth of ballon sideways between fingers to make a squeal). The only other thing I can think of that has caused vibration would be worn main bearings, but that is usually quite obvious as a rumble and metal clunking sound.

Good luck.

I agree with Colorado. This sort of problem is so complex due to the shear number of possible inputs.

An easy test on the RPM vs. MPH thing: work the vehicle up to 80, then put it in Neutral allowing the engine to drop RPM's to idle. If the problem goes away, it's the engine.

Anything on this vehicle could be causing the problem. Be patient and attentive and you will end up finding it.:)

Thanks to all. I sped up past 80 mph, put it in neutral and it still made the noise. So that eliminates the engine. Thanks for that suggestion. And I understand it's a Discovery and its going to make some noises, but I commute 30 miles one way to work everyday on the interstate and you hear these things and hope its nothing major. My power steering pump is also making a pretty good noise right now when I'm idling. Tech says its ok as long as I can stand the noise. Thanks again. And I'll try to slow down.

Ryan

TN - good to hear its probably not the engine. You might check sway bar bushings and links in front and rear. All should be snug enough to prevent you from moving the sway bar left to right in he bushings. Check your track bar up front which keeps the front axle centered left to right (it is mounted to one end at the axale and the other is mounted to the frame rail). Check tie rods, stearing damper and other similar suspension connections.

I can't remember, but if the Disco has a yolk / carrier in the rear driveshaft line I would make sure all bots / rivets are tight and that the yolk can move without play / slop. You might also check you u joints and grease those up. I have seen strange things with u joints depending on the level of pressure nad torques from the driveshaft.

If you have the ability, you might try swapping wheels with some one else. I have had tires that look fine when not moving, but the centriphical forces on a tire are quite amazing and can change alot of things at 80 mph. This goes for new tires too. I had a setof GY UHP on my ROver and could hardly keep it on the road as they grabbed every rut. I switched tires to the General Grabber At2 and have had no problems since.

You will find it. Let us know what you find.