tommytom02

My truck has a thumping/vibration that seems to be related to rotation somewhere. The truck has about 62k miles on it, it's RWD w/ a 5.0L. It started while on a road trip this past winter. First, I took it to the tire shop where I had bought tires (yes, I buy my tires 1100 miles from home when I can, don't judge me) to have them checked out. Not a lot of miles on them (Goodyear Wrangler SR-A). They said tires were good, but bad front right wheel bearing. Since I was out of state I went to a dealer (Montrose Ford in Fairlawn, OH...they're terrible, BTW). They confirmed the bad bearing and replaced it. Problem still there. After a lot of back-and-forth, driving with the service guy, he agreed it was still there. They concluded it was the drive shaft. They recommended balancing it or replacing it. They did not check it for run-out, it was a guess and they admitted that. They did road force balance the wheels and tires. Not being one to spend $1500 on a guess, I drove it home. I have not driven it much since then, just around town, but the problem seems to be getting worse. My dealer at home in DFW thought the driveshaft hypothesis was bogus, but could never isolate the problem. But they tried and didn't charge me so there's that!

I've since done some things that needed doing: Front rotors were warped, replaced brakes and rotors with PowerStop drilled/slotted; replaced rear brakes and rotors to match--discovered the parking brake was hanging due to the lever on the hub being rusted, so I rebuilt the drum parking brake assembly and cleaned it (the parking brake pedal seems to be too high in the cabin when released, but I guess that's for another thread); finally I found the front left wheel bearing to be failing (audible when spinning with rotors off), so that was replaced as well. I did all of this myself except the one bearing done at the dealer.

After all of this the problem persists. There is a thumping that I can feel in the vehicle when at speed. The sweet spot is about 40-45 mph, then also on the highway. I can feel the thumping in the steering wheel, and the contents of the cabin vibrate accordingly. I'm not sure if I can also hear it, or if that's just a manifestation of the thumping being felt by me. I am going to try rotating the spare into use to see if it is actually a tire/wheel issue. But I'm not putting any stock in that. I also have a pair of Bilstein rear shocks I'll fit soon, but I doubt this is the issue.

So, back to the drive shaft. It is a two piece drive shaft. My reading here and general knowledge says that dealer might be a good guesser, or it's the carrier bearing, the rear differential (very unlikely-I've only towed once, never abusive), torque converter (also unlikely as the noise is persistent and not related to shifting), or possibly rear wheel bearings. I do not notice any significant difference in the noise when making turns. There does not appear to be any play in the u-joints.

So, does anybody have any ideas? I hope I've provided enough info. Let me know if you need more.