This morning on the drive to work, I noticed a clunking sound coming from the transmission tunnel. It is related to speed and gets faster as I accelerate. After about 30 MPH it either stops or I can't hear it anymore.

Here's the weird thing: it stops when I apply the brakes at any speed.

Here are my thoughts:
[ul][*]Driveshaft U-joints. I know they're bad, and I'm going to replace them soon. Clunking might stop during braking because the driveshaft is now being reverse-loaded (i.e. driven by the rear wheels to the engine instead of engine driving the rear wheels).[*][*]Brakes. Although everything on the front end is new (hubs, bearings, front axle U-joints, rotors & calipers), the fact that it stops under braking suggests that perhaps something in the brake system is farked. Recently I had one of the rubber bushings in one of the calipers work its way out, although that only make a metallic thud when i went over bumps as the caliper bounced on its mount. I think it warped the rotor, too. That was the left side and this sounds like it's coming from the right. I think it's just coming up through the transmission tunnel because that's the only hole in the floor.[*][*]Front U-joints. Perhaps I screwed it up during the install? I had a shop press the old ones out, but I reinstalled the new ones myself. The shop didn't mark the axles as they took them apart, so it's possible that one of them was installed differently than original.[*][*]Front tires? They're pretty shot. Although they have a lot of tread left, I can see substantial cracking near the rim on the inside. They're going to be replaced sooner rather than later.[/ul]
Something else? Suggestions? I'm going to put it in the air this weekend and put it in drive and see if I can find it. But if anyone has thoughts, I'm all ears.

Christ, I'm sick of nursing this truck. For something that's supposed to be heavy-duty, it sure is fragile.

 

if its coming from the tranny tunnel, I would say that it is the torque converter bolts, they have been know to get loose, on somepeoples truck, I would say retorque them, because its free and easy. Starter, and the inspection plate, and thats it.

 

Wow, I never would have checked that. Good call. I'll add it to the list. New front tires and U-joints are on the way Tuesday, so we'll see if that helps.