I have read most, if not all, of the numerous (!) posts on this and other Ford forums regarding vibration issues. While I personally am not affected by this problem, I have an inquisitive side that makes me wonder why some, but not all, '04 F-150's suffer from apparent driveline vibration. I fully realize that this thread has been beaten to a slow and agonizing death, especially for those of you unlucky owners of vibrating vehicles.

The general consensus is that some 04's (both 2- and 4-wheel drive models) vibrate at certain speeds, most frequently in a highway speed range (say 50 to 70 mph, maybe less, maybe more). Most writers say that putting the transmission in neutral (i.e. coasting) has no effect on the vibration. Some people have written that force balancing the wheel assemblies helps the problem. Some people write otherwise. Most say that the add-on dampner Ford has devised is no solution.

After having considered all of the obvious things that could go wrong, and eliminating others for various reasons, it honestly appears to me that the most likely culprit is the driveshaft, u-joints and/or pinion angle, or some combination of these factors. If the vibration is still present while the vehicle is coasting in neutral, the problem, whatever it might be, is still rotating with enough force to cause a vibration. In my experience, assuming properly balanced wheel assemblies, this realistically leaves only the transmission/transfer case, driveshaft/u-joints, and rear differential. Since the transmission is effectively freewheeling without a load, it is unlikely to have the necessary force required to create a significant vibration. I suppose the rear differential could be defective but I honestly doubt it. I've never heard of a vibration of this sort caused by an out of round ring gear or faulty pinion/pinion bearing. Noise maybe but not this sort of vibration. That leaves the driveshaft and u-joint assemblies.

Other writers have suggested that the designed pinion angle might be excessive (thus causing a bind). That is a real possibility; however, why would some trucks have a problem while others don't? Different lot or manufacturer of u-joints? The same could be said about the driveshafts themselves. Some could have been made to slightly different specs (or tolerances) than others. Over the last few days, I read elsewhere that there is a possibility that Ford has issued a replacement driveshaft assembly (yoke, shaft, u-joints). Although I am repeating speculation, could this be Ford's real acknowledgment of the problem (other than the dampner device which is somewhat dubious in itself).

I don't claim to have the answer to the vibration problem. I do think, however, that with as much brain power has been exhausted on this issue here (and on other forums), someone smarter than me would have come up with a solution.

 

As a follow-up question to my post above: Have any of you vibration sufferers by chance experienced the same problem (or change in the problem) when the vehicle is carrying a sizeable load?

If there is a difference, it might suggest (certainly not prove) pinion angle issues.

 

I had about 2300lbs in the back of mine and it didn't make any difference. The one thing that I noticed missing from your post was the engine itself. If the engine (which I suspect in my case) is transfering vibrations to the chassis then you can replace all of the other driveline parts and its not going to do any good. And mine has the torgue converter, harmonic balancer, rear clutch pack, steering unit & drive shaft replaced.When you first start mine up there is no vibration. After about 4-5 seconds you can feel it start. It vibrates in park and gets worse when you shift into drive or reverse. Open the hood and the engine appears to be sitting relatively still for a running motor but when you get in the cab of the truck the vibration is there. Another thing I have noticed is this. With the vehicle running and the drivers door open to the point where it has a little resistance rev the motor to about three thousand rpm. The door is not moving. Then let off of the throttle and as the rpms come down the door will begin to vibrate in an up and down motion. In my opinion this can only be caused by harmonics and the way the engine tranfers revolutions to the chassis. Perhaps the motor mounts are transferring some of the problems to the chassis then to the cab of the truck.

 

I think it may have something to do with the motor mounts too. If you shift it out of overdrive during the vibration, does it stop? I test drove one that stopped when I took it out of OD.

 

No the overdrive trick didn't work on mine. Neither did putting in it nuetral and coasting.

 

I think the biggest problem in this discussion is that there are apparently several different vibration issues.

I'll sit back down now since mine is purely an academic interest.

 

Mine also has the vibration at idle. Its not a miss just an annoying pulse. Everything shakes. I think it would be solved by a better engine mount design. But that is not the same vibe from 45-60 that I get. I believe that is the driveshaft. Two different vibes here. Then there is the vibration from the suspension over bumps which seems much better since they installed my damper on the frame.
Yes I'm lucky to have all the vibes but the idle bothers me most as I'm in stop and go traffic alot. 04 screw 2wd 3.73ls 5.4.