I just got my first Ford, its a 1994 F250 XL 4x4 with the 351W and i believe its the E4OD trans. Its an awesome truck, i have deep mud and i still didnt use my 4wd for it. Its a beast. Its a beast on fuel too though. But my problem is that when i get to about 35-45mph the entire truck shakes like mad. I know it aint the wheel alignment cuz the vibration does not translate into the steering wheel, and its only at that speed and with fuel going to it. Im thinking its my torque converter, but im not 100% sure. Anyone have any insight? I would really appreciate it.

 

Just a thought, but check your U-joints and look for a spot on the driveshaft that may have dropped a wheight. I have seen ujoints cause vibrations when accelerating, but not very bad vibrations.

If you roll in the mud, then check for mud on both the front and rear driveshfts, and on the front axle.

 

My highway vibrations were caused by unbalanced wheels and a dented driveshaft. Vibration only appeared at 90km+ (50 mph+).

 

unbalanced tires usually causes a consistant vibration, not one that only happens only when accelerating, this is a common symptom of the drive shaft.

 

When my driveshaft was twisted/slightly bent, it shook more when I wasn't accelerating...

 

well this only happens when im on the gas and within 35-45 mph, at if i take my foot of the gas, it stops right away and its smooth

 

Drove it today and behind a tractor trailer at my work going like 3-10mph it lugged, not the engine but the truck just lugged forward back and forth at idle

 

Check the u-joints for play. If they feel tight, jack up the rear of the truck and block the front wheels. Have someone you trust get in the truck and run it up to the speed at which the vibration occurs. Lay down next to(not under) the truck and look at the driveshaft. If it looks blurry then it's out of balance. If you cant really see it, you can also use a long stick and hold it on the shaft while it's spinning. If the stick bounces against the shaft than that also means it's out of balance. If everything is smooth, then you at least know the vibe is coming from somewhere else.

 

That's a whole lot of trust!

Make sure the hubs aren't locked and the transfer case is firmly in 2H!

 

Could be the bearings in the rear end. I had the same issue, the pinion bearings were TRASHED, and I mean pulled out the bearing core and then fished out the rollers. Job really isnt that bad to do, I would recommend doing it anyway to save trouble down the road. Total cost was $45 for the bearings, gear oil, and for a shop to press the pinion bearing on the shaft by the gear. I'd look there cause it felt like my truck was coming apart at 40mph before I did the bearings.

 

I had a similiar vibration on my 96 f250 it turned out that the driveline bolts to the T-case were coming out. One bolt was gone and the other three were almost out when I stopped. The vibration started out as a little then before I got around to looking at it, it got bad so I stopped to check it out then thanked my luck stars, tightended up the three that were still there and limped her to the dealer for new bolts. So something to check for. By the way if you are missing one bolt it will give you a vibration as well as this throws the balance out.