Egress rear differential- nut backs out, loosens up almost immediately.

[Smokescreen38]

I’ve had the diff out of the Egress about four times now so I figured that at this point, I have confirmed that I don’t know what I’m doing and that I could use some input.

So when I set the diff per the manual (tightening until the spur no longer turns easily when the output/diff joints are held), the car will handle about one firm acceleration before the rear loosens and it becomes front wheel drive.   

The front differential seems to be holding up.  I built them the same way (as far as I remember) but then again, as soon as I notice the rear differential has loosened (again) I stop driving so it too might loosen up given a little more time. 
 

I’ve been weary of “over tightening” but could it be that I need to tighten them a bit harder?  The spur not turning “easily” is a really subjective term.  How do you measure that?
 

 Thread locker is not called for in the manual but would a dab of blue Loctite on the bolt that goes through the diff be worth a try?  
 

Any suggestions are welcome! 

[Snappy1]

I would tighten it more, maybe 1/4 of a turn ,  my 2013 Egress had similar issues, constantly loosening, in the end I bought the entire splitter kit and built a new rear diff, it has put up with over a decade of brushless abuse. I wouldn’t use lock tight as you need to carry out periodic maintenance and the lock tight will make it tedious 

[skom25]

3 hours ago, Smokescreen38 said:

I built them the same way (as far as I remember)

If you did this, they are not built correctly.

Look at manual. It sounds like you built it wrong and diff just unscrews itself.

[skom25]

3 hours ago, Snappy1 said:

I wouldn’t use lock tight

I assume you wrote about Loctite (Brand name) or just thread locker.

There are many types, from very weak to permanent joints.

[Smokescreen38]

On 5/14/2025 at 11:41 PM, skom25 said:

If you did this, they are not built correctly.

Look at manual. It sounds like you built it wrong and diff just unscrews itself.

Thanks. I just took it all apart again and I’m not seeing what could have been assembled wrong.  
It only goes together one way.   

[skom25]

1 hour ago, Smokescreen38 said:

Thanks. I just took it all apart again and I’m not seeing what could have been assembled wrong.  
It only goes together one way.   

Build steps are the same, but it is important to check direction of diffs.

As you can see above, rear diff has nut in short outdrive. Front is reversed, so nut is in long outdrive.

If you do this differently, it will unscrew each time.

[Twinfan]

It looks like there are only two things to check - is the diff nut in part PB13 (not PB12) and is PG1 the correct way up?

[Smokescreen38]

I was fairly certain that I built it according to the directions but I just took it apart and double checked.  It was (sadly) all matching the steps/part numbers.  Including the orientation of the spur and out drives.
 

Obviously, something isn’t right.   I’m at a loss.  The “one squeeze” on the spring strokes me as being very imprecise.  If one were to over-compress the spring, could that lead to this issue? 

Thanks again to all for the input. 

[Twinfan]

I guess if you've super compressed the spring so that it doesn't provide resistance to the nut it cold cause a problem, but I doubt you've been able to do that.

I think I'd be trying to tighten the diff more than previously and trying it again.