Thumping at wheel speed FIXED

[nimblemotors]

I've got a thumping coming from my 1998 Explorer with 5.0 AWD. It seems like it is coming from the front.
I have spent hours searching and reading mostly explorerforum posts, but others too. The simple case would be a tire was bad,
so I swapped tires around, front to back, side to side, and it had no effect, still seemed to come from front.
I actually thought it was the front driveshaft cv joint as many have that problem, ordered a rebuild kit, and removed it, but it looked in great shape.
Drove it without the front shaft, and it was just the same.

So I put it up on my lift and ran it to see if I can find the issue, and unfortunately it doesn't show up much at all when on the lift.
However because the front diff is open (not locked like rear), I could stop one wheel from spinning and see if that made a difference,
and it seemed that when the right front was spinning, I could get a little bit of thump noise, none at all when drivers side was spinning.

I checked the half shafts and the wheel bearings and no apparent wear issue. The pass side seemed a little lose, so I replace it...
and had no effect at all, same issue.

There is perhaps one additional clue is that it makes the worst thumping at 30mph, is muted around 40-45, and at 60mph is back to being real bad,
quieter at 70mph, I figured at 80 might be better, but hard to get there on our freeways, mostly I have to go 60 which is terrible, and I don't drive it on freeway for the last few months while I find time to fix it. I found some time and still haven't fixed it. Most frustrating!

Any tips given the clues? I might make a video and post it with the noise if that would help.

 

[C420sailor]

When was the last time suspension components were replaced? Ball joints, steering components, etc. A loose front end can amplify the **** out of an otherwise normal out of balance wheel (they’re never perfect).

Check torque of all suspension fasteners.

Positive it’s the front? I could’ve sworn my front end was making noise and it was a rear axle shaft bearing giving it up. Noises travel in these things.

Did it come on suddenly? Slowly? Any maintenance done right before?

 

[nimblemotors]

It started one day, but not bad, two days later it was bad and hasn't changed since then.
It is possible to be the rear axle bearing, I heard some faint noise from the drivers side rear when on the lift,
maybe it only gets bad when loaded down. I do tow a lot that puts a lot of stress on those bearings.

I might try the 'action cam' strapped underneath and see if I can isolate the sound source better.

When I get some time.

 

[nimblemotors]

So I tried putting my 'action cam' around each wheel. Turned out to be a big waste of time, the audio quality was poor, didn't help track down the source.

I have since discovered that the noise goes away when making small right turns. Freeway onramp with right curve, or just turning right to change lanes, and the noise stops. Turning left has no effect. So with this clue, I figured it must be in the front.
When it turns right, it reduces the weight on the right side, and I get no noise with truck on the lift with no weight on the wheels,
so my guess was the wheel bearing on the right front. So I replaced it. No difference. I bought two, so I will do the left side today,
but I don't think it will fix it. Now I'm thinking it is the front differential. I removed the front diff from my 97 explorer and made stub axles to keep the front bearing loaded, so I think I might try swapping those in and removing the front halfshafts so the diff doesn't spin anymore
(and remove front driveshaft, which I already tried to no effect, but the diff still spins from the half shafts)

Any other ideas on how what it might be given the new right turn clue appreciated. btw, I've just started driving it back on the freeway, and figured just let it break so at least I will not what it is, but so far still keeps going.

 

[nimblemotors]

So I replaced the left side front wheel bearings, and BINGO that was it. It didn't feel bad at all when on the truck, after removing it,
it still seemed ok, but just a little off. So finally after months my explorer is fixed (at least this problem)