Okay... so I know that that was a hell of a title and I am glad that you click and started reading. I have a few questions about my front axle. Currently I am in the stages of rebuilding/fixing it. Its not really broke... but I just slapped some 35's on her, and I know she doesn't like it.

At the moment I am in the stages of getting my Jeep (2008 Sahara JKU) Mild Off-road/Mall crawler status ready. The Jeep still drives great, and I have no issues there - its just that the last time my wheels were off at the Jeep store (High Country 4x4 Boone, NC FTW!) they told me that my ball joints were fairly worn and I look at replacing them. So recently I bought a set of Synergy Ball Joints and they are sitting in my garage. My neighbor is a mechanic, and we are going to rip it apart in a few weekends and get to working on it

Buuuuuut... he told me that while we had it apart I might as well replace my axle bearings? I am also going to put a Poison Spyder Diff cover on it, and apparently we take it all apart... so I might as well go big, or go home. All in all, I am just going to do it all at once. So... finally, after my life story, my questions are:

-Axle bearing or seals? Recommendations?
-Do I need a gasket for the PS Diff cover - videos show just using the goop that comes with them?
-Anything else I should look at while I am down there?
-U-joints? Nay or Yay?

Sorry for the super long post and everything... but I am just trying to cover all my bases before I get into it. Thanks in advance!

EDIT: Soooo after some googling, it seems like maybe I should reinforce the axle gussests? And maybe sleeve them... Advice?

I did the ball joints on mine a while back, and now have close to 100K miles on the original bearings. I didn't replace them at the ball joint change because they were still fine. When the time comes, they will not be that hard to change.

So, you have to decide if you want to spend the money on the new bearings when the old ones have not failed yet.

It seems like that new bearing are only ~100$, figured I should while I have it apart? Or no?

I guess I should lead with the question of how to tell if my bearing are bad? Or do I need to take it apart to see?

What bearings is he talking about?

My GUESS is the unit bearings.

If bearings in the actual differential go bad(carrier or pinion) they will generally make noise. If they arent making noise, IMO, no reason to change them. They also arent the easiest bearings to change. Carrier bearings aren't hard, but pinion bearings are a pain in the ass.

If he is talking about unit bearings, which are the hub bearings on the knuckle, yea probably not a bad time to change them when you have the knuckle off to do the u-joints.

If the bearings are not making noise, rotate smoothly, and have no play in them, they are still good.
I'm not trying to talk you out of replacing them; just relating the decision I made on mine.
They are easy to change when the time comes. The knuckle doesn't have to be removed to do it.

What kind of noise are you talking about...? I do have this mysterious noise going on right now. And have no fucking clue what it is. But wouldn't think its that?

Its like a random grinding, every once in awhile. At slow speeds, or sitting still. Will last 3-6 seconds. Then go away. Jeep still drives fine.

If it does it sitting still, it can't be the hub bearings.

Yea - It will do it in park. Looking on youtube for a video, that replicated the sound. But I'm getting a lot searching "jeep JK grinding noise"

you mention axle seals. If you you are not leaking any gear oil out of the front axle tubes then your inner axle seals are working and there is no need to replace them. Just use care in removing and re-installing your axle shafts after the ball joint install. When you remove your axle shafts, there should be a plastic "guide" that comes out with it. Re use the guide to help you slide the shaft back in through the seal without damaging it.

PSC dif cover. You can use the the stuff that comes with the cover, it's RTV. Have a fresh tube handy just in case. I got a tube with my covers once and it was completely solidified inside, un-usable. You can also buy a LubeLocker gasket if you want but RTV is just as good and cheaper.

Look at your U joints to see if the caps are fully seated. If they are and they are working smoothly they are good to go. If you mechanic friend has a welder, you could get him to do a spot weld or two on each cap to keep them from unseating. Your stock axle shafts use a C clip for the U joints and they can sometimes come unseated, which will cause a U Joint failure.

Awesome! Thank you so much for the help!

I'm looking up videos of "Jeep Bearing Failure" and it doesn't seem like the noise coming from my jeep is that. So I will wait on the bearing if need be.

It does seem like one think that we should all look at while running 35s is reinforcing the C-gussets. So maybe go ahead and put on those Evo bracers while I am in there. Also might as well do the u-joints now as well.

God... the more you look at Jeep axles the more stressful it gets. I'm wanting to drive it - but now I am so paranoid that its all messed up and gonna fall apart while I am driving. So that I should just buy Dana 60s and never drive it until then. Ha.

Thanks for all the advice! Now... to just find out the odd noise. Haha

while you have the balljoints out, do yourself a favor and find a mig welder and do "C" gussets. Differential bearings should last longer than the rest of the jeep. Unit bearings are no problem to replace later on down the road if they end up causing problems. seals, if the tube seals arent leaking dont touch them. that will require pulling the diff out. The pinion seal is no big deal to replace later on if it starts leaking. The only thing I would suggest replacing while you have it apart would be the knuckle Ujoints.