Do I need to open the diff when replacing ball joints?

[toximus]

By this I presume it is meant to not just jam them in or is there something else since I won't be able to see the seal.

Yeah, don't force it. As you slide the shaft in you'll feel the seal in there, using both hands lift the shaft end slightly to fit it through the seal. Also if your tubes are full of junk you'll want to not push the shaft through all of that. Clean it out if you can or, again, use both hands to keep the shaft off the tube.

I bet it's original with 91K on it.

If you don't know the history of it (or you know it's that old), now is a good time to start establishing history of fluid changes.

I suggest you also look at the owners manual which lists the service intervals.

 

[toximus]

I wouldn't assume anyone's gears would be fine using synthetic inside the diff. Not since it was learned that the gears run hotter with a synthetic gear lube. Hot enough to do damage? Maybe, maybe not. But it was hot enough to damage my new gears last year after filling the axles with synthetic after getting talked into it against my better judgement.

There's plenty of other threads where we can argue about this. I have one set of axles that I run ONLY Torco conventional in and a set that I only run synthetic in. I was told to run the synthetic in that axle by somebody who has done more fluid changes than I probably ever will in my life so I'm comfortable with it.

 

[dudehitt]

Yeah, don't force it. As you slide the shaft in you'll feel the seal in there, using both hands lift the shaft end slightly to fit it through the seal. Also if your tubes are full of junk you'll want to not push the shaft through all of that. Clean it out if you can or, again, use both hands to keep the shaft off the tube.



If you don't know the history of it (or you know it's that old), now is a good time to start establishing history of fluid changes.

I suggest you also look at the owners manual which lists the service intervals.

I had my Dana 30 open when i did ujoints, axle shafts, and unit bearings. Just keep the splines out of the junk in the tubes. Didn't replace seals, no leaks.

 

[Sundowner]

I take it this is what you're referring to?

https://www.quad4x4.com/catalog/category/axlesealtools

Similar, but no. Those are all for Dana 60's and 44's, and although they function in the same basic way, there's a specific tool for the TJ's 30 or 44.