Driveline Vibration

[Simp5782]

My 94 IDI has a vibration at appx 70mph +. I can feel it in the seat and it sounds like it is coming from the rear of the truck but it could just be an echo. I recently replacing my 4.10 with a 3.55 and I had the same thing with it, but when I go up to round 80 or 82 the noise and vibration goes away. The ujoints seem tight, the center support bearing has a lil movement but not like clanking away. The transmission mount is new. Are there any suggestions to what it might be? Should I just throw parts at it, like all new u joints in the rear and a support bearing? or Could it be something else?

94 F250 S/C IDI 5speed.

 

[Reddually93]

Maybe tires out of balance?

 

[Simp5782]

naw, it does it with my 245 75 16's and my 37x12.50x16.5s that i swap out to on occassion. Both have been road forced balanced.

 

[forcefed]

Get the driveshaft balanced, And if you are doing that get new u-joints installed first so it will be fine for awhile.Sometimes after new u-joints are installed if you did not put everything back together just the way it came apart it will create a vibration just like you described. Mine did this when i tore mine apart but I just went ahead and got mine balanced and no problem since.

 

[franklin2]

I am not sure about these later trucks, but I know a late 70's truck with a center support bearing has a slip yoke at the bearing. And this slip yoke can be installed wrong on the earlier trucks.

Picture the end of the driveshaft with nothing on it, no u-joint or anything. It will be a "U" shape. When you slide the slip yoke onto the other end, it has a "U" shape to it also. These "U" pieces need to be prefectly aligned so the joints work together. One spline off and you will get a vibration.

Like I said, the earlier trucks can get off, but some splines have a key spline and it won't let you install it wrong.