I replaced the upper and lower ball joints on one side (driver). The seals were busted and could hear them clunk when I hit bumps so figuered it was time to replace them. So that was a fun process but at least I know what to expect on the other side. So after I finished took it for a drive and right around 63-65MPH I get a slight to moderate shimmy. Funny thing is that sometimes and I'm not sure if its the road surface or the pitch of the highway, it doesn't shake but most often it does.
So did replacing one have an effect on the other side that probably needs to be replaced, did I damage a bearing taking it off, were the new ball joints bad, any other thoughts? Anyone ever run into this? I still plan on doing the other side btw....Thanks. 1996 jeep 4.0 and I have the shop manual and torqued everything down correctly.

check the exhaust and make sure its not rubbing up against the cross member. i had a similar issue with mine, around those speeds and come to find out it was just the exhaust vibrating up against the cross member. not saying this is what yours is, but worth double checking.

Doublechecked it, doesn't seem to be the case. I need to replace the passenger side eventally so I guess I'll see what happens then.

Often a wheel out of balance will only act up at a certain speed range. You might want to check/rotate just to rule that out. Might be free.

Check the wheel bearing on the side that you did ball joints. Any movement of the wheel will indicate a bad bearing.

My bearings are pretty bad and I get shimmy if i slightly turn the wheel left, right or hold straight.

Wait... You said you damaged a bearing? Did you replace it? If so a balance and rotate would be good. Are the tires good? I've got a little flat spot on one of mine and it causes a sorta up and down wobble, not a side to side wobble. Other than that, get the other side done and see where your at with wobble.
Oh, are all other steering/alignment components good? Ends, bushings, etc?

No, don't think i damaged the bearing, I was just thinking that it may be a possibility. I'm going to check the balance/rotate the tires, they are a year old 80K treadwear on them so they are in good shape. The bearing I pulled off with a puller as it was stuck when I did the balljoints and the passenger side balljoints still need to be done.

OK rotated the tires, now the shimmy is almost down to nothing and only happens between about 68-70 mph. I'm going to to get them balanced and hopefully that's that. Thanks for the help, lately it's been one thing after another so I've been preparing for the worst. Not the case this time though....