So, I installed a Rancho 4" sport lift 15 months ago on a 2 dr JK Runicon '08 with manual transmission. It's been great, I like the ride, put 35s on and never looked back. However, my stock rear drive shaft his making bad noises and has spit all its grease out. Time for a new one. I'm planning on using a coast 1310, I guess. My question is: with this lift, the drop brackets are basically supposed to maintain stock geometry. Therefore, do I need adjustable rear upper control arms to fix the pinion angle, or is that not related the the current driveshaft failure? I'd really like to not spend the additional $3-400 right now, the driveshaft will set me back enough. However, I don't want to screw this driveshaft up, either.

 

I believe you do and lifts of three inches or high is where it becomes an issue. I just found out the same info about the four door and the front DS. But remember reading something about the rear on the 2D. I also order adjustable control arms for the rear to correct the angle and hope that I can prolong the life of the driveshaft.

 

Well, unless anyone has any further thoughts, I'm going to order just the driveshaft and see what pinion angle I get. If it's more than 2 degrees off, I guess I'll order the rear upper control arms afterwards. At least a new driveshaft will be getting me around town in the mean time.

 

Just replaced my rear DS. Highly recommend control arms at same time. CV does not like angles - wants to be straight thru at the transfer case. You'll wear out the new driveshaft prematurely, and might as well install while you are under there with all the tools anyway.