Hoosier Daddy
SILVER Star
I have a 95 with an Ironman 2.5 lift, Arb bumper, no winch, and a Mr Gasket 1" (3/4" in reality) spacer in the front to compensate for the ARB. I have the Slee caster bushings.
I searched Mud and came up with the front pinion bearing or transfer case output bearings as possible culprits. I removed the front driveshaft and checked the flanges for any up/down, side to side play, and found none. Just the expected mild rotational slack in the differential flange and a tiny bit of in/out on the transfer case flange. No leaks from either the pinion or transfer case.
I'm stuck. What am I missing?
- Truck has developed a rumble/mild vibration at speeds above 60 mph when in-between slowing or accelerating (ie, no load on drivetrain).
- I think I have recently started to notice it a little bit under similar conditions around 40 mph, although not nearly as pronounced as at higher speeds.
- It seems to be worsening with time.
- Onset was well over a year after the lift and caster bushings, but before the ARB and Mr. Gasket spacer.
- Adding the ARB bumper and later adding the spacer did not affect the rumble noise or vibration. (The ARB had dropped the front about 3/4 inch, so I added the spacer.)
- Removing the rear driveshaft does not affect it at all.
- Removing the front driveshaft makes it go away completely.
- I had both front U-joints replaced with Toyota OEM without any change. I later tried switching the driveshaft orientation to in phase, with no change.
- The front axle was re-done a while back, with all new bearings. Wheel bearings are tight. I was sure I had greased the spindle bushings well, but in desperation I tore it all apart and double-checked. All good, but greased them up some more for good measure. No change. Spindle bushings seemed to look normal.
I searched Mud and came up with the front pinion bearing or transfer case output bearings as possible culprits. I removed the front driveshaft and checked the flanges for any up/down, side to side play, and found none. Just the expected mild rotational slack in the differential flange and a tiny bit of in/out on the transfer case flange. No leaks from either the pinion or transfer case.
I'm stuck. What am I missing?