Truck or Trailer Shake at 0-30 then again at 60mph?

Use a temp gun to take temperatures of the tires and hubs after a long drive. Usually the hottest tire or hub will be the problem. Vibrations can also be from the drive line not set properly, angles where the driveshaft meets the rear differential. Sometimes a piece of branch or something has changed the air ride suspension adjustment rod and that can cause vibrations. Check all the steering links, could be the rod that goes from steering sector to axle or tie rod ends. Also look at the torque arms on the rear axles, the rubber bushings wear out over time and need to be replaced. Look for unusual tire wear and if you let go of the steering wheel while driving, does it pull one way or the other? Run your hand over the steering tires, if the have sharp wear edges, could be toe in or out. Contact the alignment guy at Des Moines or Kansas City, Mike Becket.

 

Seems like you have a couple of different problems. The shaking at low speed after going over the tracks is either a worn drag link, or the pitman arm is loose on the sector shaft. Turn the steering shaft by hand gently back and forth and look for movement of the sector shaft inside the pitman arm. If it's tight, I'd probably replace the drag link.

As for the vibration under a load, that definitely sounds like a driveline problem. Maybe pull the driveshafts and take them to a driveline shop and get them checked for balance and twist.

 

I would check the air pressure in the tires,might be over inflated.

 

Are they all old steer tires on the trailer?

 

I had a very similar issue when my company was using goodyear tires. Like you, I actually thought I had blown a steer tire it was shaking so violently. Turns out my steer tires were going out of balance and out of round. Convinced boss to switch to Michelins, and had them properly balanced, and it 100% went away.

I know you said you are already running michelins, so I guess I would suggest rechecking the balance. And don’t use those stupid auto-balance beads, make sure they put it on a balancer and do it the right way.

I’m no mechanic, just wanted to share my experience before you start tearing the whole front end apart.

 

I had a bad shock on the drives,right rear,it was smooth until I got up to 60,then it shook the truck bad.Replaced the shocks and the shake went away.