So, I drove my truck on the interstate for the first time this evening. I've driven around town up to about 45 MPH with no issues at all, except an occasional hard shift into 4th (how I have a 4th gear is an entirely different question). Had to go pick up some patio furniture across town, so I took the interstate. Driving the beater into a neighborhood of million dollar houses was fun Anyway, doing 55-60 there is a noticeable shake going on. I made it the 20 miles there with no issues besides the shaking, but I decided to take regular roads home. I need some thoughts as to what might be going on, that I wouldn't notice at 45, but is obvious at 55. Unbalanced tire? Bent axle? Bad wheel bearing? Transmission issues? something else? I don't foresee spending much time on the highway, but it would be nice to be able to if I need to without the white knuckle ride the whole way.

 

Id check your wheel bearings real quick. Do this by jacking up the front of the truck and grab the top and bottom of tire and try to move it in and out of the spindle. If it moves more than .005'' than you should remove the wheel, check the bearings and repack them if they are okay. You can also before hand spin the wheel and listen for any free play, resistance or any odd noises.

Id also check out the front end and make sure that its not noticibly out of line. Might just take it to a shop and see if they give free check ups and such. My neighbor neal tire will take it and diagnose all the problems and give you a list of whats wrong for free.

 

Also check the tires for cupping, wear and balance

 

All previous suggestions are good. Try placing the front tires to the rear and rear to front and see if the shaking pattern changes. If so, that might indicate a bad tire(s) or bent rim. Make sure your lug nuts are properly tightened. Check your air pressure. This is a safety issue, so check into it right away.

 

Wow can't beleive nobody mentioned the driveline yet. Given the relatively specific and high speed I'd lean towards the driveline. If it's out of balance, or the bearings/u-joints worn out it can start to spin around like a jump rope at those speeds.

Just get under the truck and give it a good shake and see if it moves, shake the ends next to the u-joints, and u most likely have a carrier bearing that supports a 2 peice drive line, give it a good shake to.

 

I concur, the majority of the time I've had that issue it was bad u-joints, other times the driveshaft threw a weight.