Vibration at ~40mph

So I first noticed this when towing the camper for a few hours. I get this vibration around 40mph or so, feel it most in the seat.
Starting to feel It now even when unloaded. Assuming something driveline related, maybe U-joint? They’ve never been replaced. I have replaced carrier bearing with a spicer unit about 5 years ago. Haven’t gotten under the truck yet to inspect. Feels like a rumble. Changes when I let off the gas.

 

That's weird; is it 40 and over? Or just at 40? I figure a bad joint would be noticeable regardless of speed.

 

Right around 40, goes away over about 44mph

 

You sure it's not a tire issue?

 

Is it every time you hit 40 or above? I'd pull the rear driveshaft and go for a spin in 4-HI to see if anything changes.

 

Tires are usually a 55-60mph thing, but can’t rule out tires as they are new

 

When I had this problem, first I had the tires re-balanced (didn't fix) then rotated (didn't fix). I replaced the carrier bearing (didn't fix) then all 4 u-joints (didn't fix). Had the drive shaft balanced (didn't fix). The double cardan joint is not serviceable (no parts available), but the drive shaft guy said it was fine. Finally took it to my trusted mechanic who diagnosed the problem as a bad right front hub bearing. Fooled me because it was silent (I thought a bearing failure would sound like two cats screwing in a dumpster). Had it replaced (fixed!)

 

If it’s vehicle speed dependent and only present at certain speeds it’s probably a wheel bearing.

My RR wheel bearing went bad on my 2021 this summer and it got to the point where it sounded and felt like a Honda Civic with a fart can exhaust at exactly 59 MPH. Above/below that it went away, and it seemed to get worse during engine braking.

The vibration/noise always got progressively worse with increasing vehicle speed any time I’ve had a bad u-joint in a vehicle.

 

I’ve replaced both front wheel bearings with OEM Koyo bearings in the last couple months.

 

I hate that this fits my current situation.

 

I'm almost positive that's what mine did when a u-joint failed. Because I would leave work and was on a highway that you usually only went no more than 50 or 55 miles an hour. so it would go away once I got up to full speed and then once I hopped on the interstate I didn't hear it at all

 

I think this is everyone’s biggest fear, throwing parts at stuff, doing all that xtra work/. Knowing the better driveline shop in town, south of ATL, does free diagnostic, if I ever get a vibration and it’s not blatantly clear what it is (like U-joint or carrier, all look fine), they’re the first place I’m going and I’ll kick ‘em a $50 or something to run a full diag. Beats busting out the parts cannon. Not that I wouldn’t love to refresh my entire driveline, I just don’t like throwing away money.