I have a paystar 5500 tri dump truck, It has started shaking at 60-65mph LIST OF THINGS IVE CHECKED: checked front tires tighten bearing( no movement when checking bearings on front after tight) Tightened front rear yoke and replaced universal joint Checked all other joints and all were good exept rear front yoke, a little loose but not bad ANY OTHER IDEAS ITS DRIVEING ME CRAZY!!!!! THANKS AHEAD FOR ANY INFO.
read this thread all the way through: I have found vibration at certain speeds is usually tires. Good Luck, Mitch
Very often you can determine a wheel/tire vibration versus a drivetrain vibration by letting off the gas momentarily and then reapplying power. If the vibration noticeably changes for the better, or goes away under coasting it's a drivetrain problem. By doing that on a level road you've eliminated a tire/wheel problem because the tires are basically spinning at the same speed they were before you went into coasting mode. This is easier with automatics as you don't have to push in the clutch to coast. If you do this and the vibration remains it's probably your wheels/tires. Anecdotal: Last October I replaced the tires on one of my pick up trucks and driving for the next two days on country roads never exceeding 50 mph I had no vibration. On the third day I got on the interstate and when the truck hit 55 mph I lost a few fillings in my molars. At first I thought the tires weren't balanced when they were installed. I had less than 30 miles on them, and as they were the only thing that changed on the truck they were a good candidate for suspicion. But doing the above exercise told me the tires were fine, the drivetrain had a problem. Turns out what little life I had left in the rear u-joint was used up pulling a loaded trailer up and down the mountains from West Virginia to Virginia. Two days after the trip was when the tires were replaced. I only had the vibration at high speed. You said you replaced one of the u-joints. It wouldn't be too big a surprise if one of your other u-joints is the culprit. I'm sure you do this, but the drive shafts need to be under zero tension to really get a feel for a u-joint going bad. If the drive shaft has rotational tension on it from either a parking brake or the transmission it can fool you into thinking it's tight when it may be missing some of its' needle bearings.
Is it air ride? If the ride height is off, it will put the u-joint angles out and cause a vibration.
If not the joints, yokes, carrier bearing, or tires, could have an egg shaped brake drum or wheel. Doesn't have to be bad enough that you can immediately see it. Won't necessarily see it in the tire either if it is a wheel. Release the brakes (chock a wheel) and jack up each wheel separately. See if they turn on their own, (heavier in one spot), turn them to a couple different spots and see if they do this. Could locate the defective drum or wheel this way. However a out of balance tire will spin it too. Drive shaft could be out of balance as well. This could have caused you to have loose bearings/yokes. I don't know how long you've had the truck or what it's been through, but could be one of these reasons.
Is your vibration with the lift axle down ? If it is then the coil over shocks on the tie rod need to be replaced.