Over the last few weeks I’ve noticed a vibration of sorts with my truck. It’s barely there, but I notice it and feel it’s getting more prevalent.
It’s only noticeable above 55. It isn’t in sync with engine or wheel speed. The best I can describe it, is that it goes in and out like when your phone vibrates with a silent alarm- on then off, on then off. Sometimes with a 1 second pause, but sometimes even shorter. It changes frequency, even when rpm and speed are steady. If going say ~65mph with the gas on, the vibration is as described, but it seems like when I lift(no load), the vibration significantly dissipates or disappears. If anyone has ever ridden a dirt bike at constant high rpm in a desert or dual sport situation that doesn’t have a balanced crank, it’s almost like the harmonic vibration you feel between your ankles when squeezing the case.
At first I thought maybe it was the driveshaft. I recently put new u-joints in when I had my driveshaft out to replace my pinion seal. Tomorrow morning, I’m having it balanced. The weird thing is they balance it with the transfer case yoke attached, but not the diff yoke. Why do people say to keep track of driveshaft to diff yoke orientation if they aren’t balanced together?
The other moving items I haven’t replaced:
—th400, feels fine & shifts well. New oil and filter a couple thousand miles ago. Oil that was drained out also looked brand new.
—bearings in transfer case, the splined shaft on the yoke side has no noticeable play with driveshaft removed and the seal never weeps oil as I’d suspect it would if vibration were present there
—any bearings in the 14bff. It has new fluid and again the fluid that came out looked really good. I have all new wheel/hub bearings, just haven’t had the time to install. I wanted to look at the condition of the shaft where the bearing rides as well as the splines when they come out.
Only other culprits I can think of might be wheel/tire balance, but both are brand new, just rebalanced when rotated and it’s not in time with revolutions. Not sure if that last point can rule them out or not. Also, haven’t gotten around to replacing tie rod ends or rebuilding my D60 kingpins. The truck has really low mileage and was maintained by the military, so I’m assuming they kept up on greasing the kingpins.
I did go through and recheck torque on all suspension and steering items since this truck was fully disassembled and reassembled by me and everything checked out.
Thanks Guys
