420U Differential - Ring and Pinion Backlash

[Jreb10]

I removed the back cover to replace the PTO seal, and checked the ring and pinion backlash just to be thorough. Well, it measured around .024" versus the specification of .006 to .0012. The tooth contact pattern on both the drive side and coast side was pretty much OK.

Does it make sense to consider reshimming to reduce the backlash to the specification? Could it cause more trouble as less worn parts of the teeth now begin to make contact?

I am not trying to make it quiet, I just want to do the right preventive maintenance. Would it hurt it to just leave the backlash as is?

Any experienced comments are appreciated.

 

[Lee B]

It probably won't hurt to leave it alone, but it would be best to remove .010 to .015 of clearance if you can do it while in there easily. If you do try to correct the situation, remove it equally from both directions, eg. shift the ring gear 6 thousandths toward the pinion and extend the pinion 6 thousandths into the ring gear. Re-measure of course.

I fail to understand how trouble can result from correcting a clearance issue. Perhaps you are considering a tab bit too much black magic afoot? Any is too much black magic, you do need to keep .006 to .012 of clearance, however.

The nice thing about worn together parts is that they are usually happily married.