John Deere 990 4 wheel drive problem

[Markbasinger]

My John Deere 990 4 WD makes a clunking sound when placed in 4WD. I visually inspected and see no obvious problem. The shift lever to engage the 4wd operates ok-no bind. I am attempting to remove the front drive shaft to inspect where it goes into the front differential. My technical manual gives no instructions on this. I removed the bolts securing the drive shaft to the differential but it will not completely pull out. Any suggestions regarding removal?

 

[Markbasinger]

Here is a picture of the frond drive shaft where it enters the differential.

 

[Markbasinger]

Able to pull the shaft out after taking the weight off the front tires. Out popped the ball bearings at each end also but found them easily. The problem appears to be the rear coupler is worn, causing it to "hop" over the ball bearings which make the clunking sound. I will attempt to fix that and be back on the road.

 

[Citydude]

Good you found the cause. Keep us posted on the repair.