Last summer or fall, I pulled my rear driveshaft to lube the splines on the 93. Put new tires on a while later and have been unhappy at a freeway vibration the tire shop doesn't seem to be able to get rid of that I attributed to the tires.
Yesterday, I repacked the wheel bearings on the other 80, and lubed both truck's shafts while I was into the grease. Whups, what's this? On the 93 the rear shaft grease fittings don't line up. Unbelievable - I put the rear shaft section on 90 degrees out of phase! Fixed it, and most of the vibration is now gone.
So, to anyone who's got an unexplained freeway vibration, consider being sure that your rear drive shaft is properly installed IN phase (ears on the shaft portion in line with each other at each end), and that the front shaft is properly installed OUT of phase (ears at each end 90 degrees to each other). Your grease fittings should be very close to a perfect straight line.
I'm such a bozo sometimes....
DougM
Yesterday, I repacked the wheel bearings on the other 80, and lubed both truck's shafts while I was into the grease. Whups, what's this? On the 93 the rear shaft grease fittings don't line up. Unbelievable - I put the rear shaft section on 90 degrees out of phase! Fixed it, and most of the vibration is now gone.
So, to anyone who's got an unexplained freeway vibration, consider being sure that your rear drive shaft is properly installed IN phase (ears on the shaft portion in line with each other at each end), and that the front shaft is properly installed OUT of phase (ears at each end 90 degrees to each other). Your grease fittings should be very close to a perfect straight line.
I'm such a bozo sometimes....
DougM