2000 sport 242 t case, 4.0, 8.25 rear, dana 30 front..no lift 235 75 15 tires.. so I've been hearing a humming/vibration in my front it seems more prominent @ between 40 mph and 50. Changed front diff fluid,looked great all the gears looked good to greased the zerk on my front driveshaft.. rotated tires. I do have a full size spare on front with a lil less tread than the others but the noise was in front before I rotated. Sounds jyst like a bad wheel bearing but it doesn't get worse when i turn left or right. I know noises are hard to diagnose via internet just wondering if anyone has any insight or has ever delt with it also.

 

Could be:

Hub bearings
Pinion bearings
Ujoints
Carrier bearings
Or something else altogether


The fact that it comes on at 40 to 50 would point to a bearing in the diff.

Does it happen when coasting, during acceleration or both?

 

Not very audible when accelerating, does not change in neutral....I seriously want to fix it but im afraid I'll not be able to find the source before something messes up worse

 

This should help, from the FSM.

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Sounds like it may be the differential bearings (the ones at the ends of the carrier). If it is not that bad and doesn't affect performance, just drive it until they go, which could take a long time. They may have a lot of noisy-life left and not worth it yet to fix because finding a shop to do it right is tough and expensive and DIY is tough too.

Good luck.

 

Sounds like I have a similar issue. I get a humming noise only on deceleration, at around 60kmh (about 40-45 mph I'd guess).

I checked all u-joints and everything I could think of, but the sound still there. I got it checked by my mechanic and he too says everything looks fine and the bearing doesn't have any play in it.

I figured I'd just wait it out, if it really is the bearing it's not gonna be cheap to replace, so I'm not in a hurry and will do it when it's absolutely needed. I was quoted 4-5 hours to replace.

 

Well it's a bit embarrassing but I wanted to update and I can finally say the sound is gone.
Apparently I should have put the wind deflector that came with my roof basket on. So I did, and that stoped the noise.

 

Ha, I done something similar. Just laugh at it and move on.

Glad you figured it out.