My 95 4runner has developed this nice massaging vibration in the floor board that consistently hmms up and down (more and less) as I drive. The wheels have been balanced in the near past, not sure if it could be my CV joints, unbalanced drive shaft, unbalanced tires?? any ideas??

 

Have you removed and replaced your drive shaft lately? if so did you get the flanges lined up? Is your drive shaft dented any where? When you grab your drive shaft and wobble it a bit, does it have any play? Do you know the square root of 92837... If you said yes to any of these questions then your well on your way!

 

is the hum affected by engine speed, or road speed?

 

Carrier/center Bearing on the two piece driveshaft?

 

Bad/froze u-joint? Broken belt in a rear tire? Wheel falling off of a corner? Vivid imagination?

 

The hum is present at any speed, although it increases in volume with rpms?? The U-joints seem ok and the tires are new and still on the truck. SOmeone mentioned a gasket or seal between the tranny and transfer case?? anyone familiar with this?