FJ40 Transfer Case Rear Output End Play-Vibration Issues (1 Viewer)

[h82crash]

EDIT: Vibration solved. I still need to correctly set my bearing preload. Shims ordered. My fix in post 5.

I am having drive line vibration unlike the common symptoms. Start at about 50 MPH and very subtle, if any, under load, but very noticeable coasting or between accel and decel loads. I checked the rear driveshaft and there is minimal rotational lash in the splines and U-joints appear good-no slop and smooth.

But, the parking drum has in-out and lateral movement. I suspect this is the cause. I cleaned the TC and replaced seals and shimmed it the same as I disassembled, thinking it was correct. Clearly, I know now it is not correct.

I think it had the vibration before I did the work, but I seldom drove it that fast. I now have a 5 speed OD and an LS so I'm driving the higher speeds more often. Also have better tires and a hard top so these vibrations are more noticeable.

Looking for opinions if the loose output is the cause. Well, the more I think about it, I need to correct this first and see if I need to go further.

 

[45Dougal]

I'm curious to see where this goes as I have similar symptoms albeit around 60mph on my HJ45.
Feels like driving on a very slight corrugation when it happens.
Drive faster or slower.

 

[Grayscale]

Mine were at 60 mph. Leak at transfer case rear output, and on the rear pinon. The double cardan driveshaft was advised, but, I never got that far. A double cardan driveshaft requires rotating the spring perches on the axle. Tom Woods has some tech articles on driveshafts. The greater angle of the u-joints makes them move in an ellipse when the driveline is angled from lifted springs. The ellipse means that the driveshaft spins faster and slower every rpm. The ellipses can cancel each other out, if the transfer case flange and pinon flange are parallel; check it with an angle finder.

 

[archie73]

I’m no expert, but I seem to recall there being a preload measurement when putting the nut on the output shaft. If this is out of spec, it would likely allow the lateral play you mention. Perhaps you can redo that preload and eliminate the shimmy.

One other thought is the drum- are the bolts that hold it on tight?

 

[h82crash]

Thanks for everyone's effort. Yes, my u-joints were in phase and my flange angles are parallel. BUT, I had the shaft halves 180 degrees out. I turned the rear half 180 from where I had it and smooth sailing. Yes, I still will set the TC bearing preload.

 

[45Dougal]

Ah that's interesting, maybe I missed that when I did the hand brake.
Fwiw, my drive shaft is around 4ft long (HJ45) so my angles are less extreme than you shorty guys

 

[charliemeyer007]

"But, the parking drum has in-out and lateral movement. I suspect this is the cause. I cleaned the TC and replaced seals and shimmed it the same as I disassembled, thinking it was correct. Clearly, I know now it is not correct."
That's where I'd be looking