I currently have the 2" OME HD springs with front upper adjustable control arms. I am switching to the Rock krawler 2.5 triple rate springs. I am trying to get a starting measurement for the Upper Control arms to start caster. Any Ideas? I know it will still have to hit the alignment machine once their installed.

 

Rock krawler has measurements included with their lift kits, I'd go pull down a current copy of the instructions and see what they say. The other option would be to check in with someone like Metalcloak or Teraflex. The brand of the coil doesn't matter so much as the length of the arm for a particular height.

 

Factory uppers are 18 3/4". I'd start with 18 1/2" and that should be close. Page 9 here on the Metalcloak instructions using factory lowers says 18 3/8", but they note that for 5* caster and don't specify if for 2.5" or 3.5" lift.

http://www.armoredworks.com/metalclo...e-Lift-Kit.pdf

I'd start with that, check alignment, and you might need to tweak one time accordingly.