nthinuf

There is no set-in-stone answer, as there are factors other than lift height involved. Your best bet is just to make a habit or crawling underneath and looking for grease splatter. The higher you go, the more often you should look.


How do you get to the ball inside the double cardan end without dropping it?

EzK

Do JK rears crap out that fast? My 4" TJ made it 15k before a u joint roasted from the lift.

nthinuf

Depends on the specifics. With your 4door and a 3-4" lift, the rear driveshaft should be ok. On a 2door, expect to have issues.
On both 2 and 4doors, the front shaft may have issues. Auto's have trouble with the boot in the middle contacting the skid and the corner of the tranny. 6spds may have issues contacting the exhaust. Both may run into issues with the angle of the joint at the tcase.
If you crawl underneath and look at the tcase, you will notice that the front output is tilted upward, which increases the angle that the joint operates at. (it took all of 5k miles for me to lose that joint with about 3.25" of lift). As noted, there are a lot of variables involved, so it just depends...