I haven't taken it to the dealer yet, but I wanted to see if anyone might be able to speculate on what my issue might be. I have a 21' XLT SBSC with the 5.0 and FX4.

Basically, I have a small vibration that I'm trying to pinpoint. Probably started about 1k miles ago or so. Truck has 22K on it At no point is it that bad, but it's enough to know that something isn't quite right. It's just a steady vibration that builds with speed. It shakes the entire truck. I can feel it in the steering wheel, but not really more than the seat/console or anything else. it doesn't seem to be in relation to the steering in any way. It can blend in with road feedback until I get up above 50-55 and then becomes apparent enough to know it's not the road. If I'm on a silky smooth road, I can feel it above 10-15mph. It also seems like it varies in severity slightly all else being equal. I can also feel/hear slightly it if i brake hard. Just low frequency road-noise type of sound that syncs with the vibration.

I initially thought it was my OEM tires. They were getting pretty worn, and so I got them replaced with some Michelin Defender LTX M/S2's, but the vibration persists. I had the tire shop rebalance, but they said they weren't out of balance, and they couldn't find any defects. Since I was already experiencing it with the old tires as well, I think I can rule them out.

I can't rightfully tie it to engine speed or gear, and it will even do it rolling in neutral.

Anyone have any idea what it might be? Rear wheel bearing maybe? I'm afraid to blindly take it to the dealer, they seem to do an awful lot better if I already have an idea of what the specific issue is and can point them in the right direction. It's also subtle enough at this point that I'm afraid they're just going to tell me "that's normal" if the wrong person drives it.

 

I'm just throwing an idea out there, but what you described seems like it might be exhaust drone noise. Does the truck have aftermarket exhaust?

 

Stock exhaust. It's definitely not the exhaust. The vibration is directly related to road speed. There's not necessarily even a sound involved unless I'm braking. It's definitely driveline related.

 

Any vibration in the brake pedal when slowing down?

 

Not any added vibration, any vibration I can feel is pretty uniform throughout the truck.

 

The only thing left to do would be to take each wheel off and start inspecting the rotors/brakes for anything unusual/loose.

You did mention it's a "steady vibration that builds with speed", maybe take a look at the driveshaft/u-joint?

 

I think drive shaft or u-joint makes sense. I've noticed a little slop/clunking from time to time recently. Just figured I needed to get the slip-yoke greased, but I suppose it could be a u-joint. I think that's the direction im gonna go with. I'm struggling to think of what else it could even be at this point.

 

What the hell. So i did some running around after work, and It didn't vibrate at all for most of the evening, and then started doing it about 5 miles before i got home. Definitely wouldn't think it's the driveshaft in that case. Can a bad u-joint account for that kind of behavior?