It seems like I am one step forward, two steps back on this. I just finished replacing my blown factory shocks and my hard as a rock BFGs. I have Bils and new 31X10.5 Bridgestone's and just had an alignment done.

I take it out on the highway and at first it seems fine. Then as I approach 70mph a start getting a vibration. There is almost no vibration or shaking of the steering wheel other than what is felt through the rest of the truck.

Below 40-45 mph, it goes away.

I took it out last night and tried to isolate as many conditions as I could to give the best description I can.

-Seems to kick in around 40-45 mph, especially when trans kicks into O.D.
-Little to no feedback through steering wheel
-Vibration roughly equal on acceleration and zero throttle deceleration in gear. Giving just enough throttle to keep up with speed of vehicle minimizes vibration.

Truck is 1995 T4R 3.0 auto

 

Tires out of balance.

 

Are you where all the snow is hitting now? Picked up any snow behind the wheels??

 

Check your u-joints, and grease them. I have a similar issue.

 

40-45 and 70 miles per hour seems like the sweet spot for unbalanced tires..

had this happen on numerous vehicles with numerous different wheel/tire combos

 

I am where we are getting all of the snow, but the issue arose before the snow came.

I just had the driveline lubed in the last 300 miles.

I guess I will take them back to where I had them balanced and have them redo it and see if it improves. I just had them mounted at Sears, they should have adequate equipment for balancing the tires right?

 

Equipment might be adequate but the help not so much... I would also check the u-joints just cause its free, again, just cause someone can run a grease gun doesn't mean they actually checked the u-joints...

Another thought on tire balance, tire shops usually put the worst balanced tires on the rear if they can't get them perfect or are too lazy too. Putting them on the rear makes the imbalance less noticeable. If you don't call them on it, they'll keep doing it.

 

If not the tire balance, I'd look at driveline. U-joints (as mentioned earlier), the bolts holding the driveline to the t-case or third member could be loose or missing, or the big 19mm nut holding the plate to the t-case or third member.

Get under your truck and with the truck turned off and in gear, rattle your driveline in a circular motion. If there is any real movement in the driveline that doesn't transmit immediately to the third or t-case, you have a problem.