I was curious as to why you can run a 2.5" BB without a trac bar and control arms but when you get a coil lift you need them? Does the geometry really change that much with a taller coil vs a stock coil with a spacer??

Edit: I'm only asking this in regards to a 2.5 coil lift not larger

 

I think it's really best to get them with any 2.5" lift, whether it's a BB or coil lift. However, you can get away without them, and most people getting a 2.5" BB vs 2.5" coil lift are trying to save money and/or have a simpler install, so they aren't included with the BB.

Also, a 2.5" BB is 2.5". Some coil lifts are a little taller than they advertise in order to make up for heavy front/rear bumpers. Without heavy bumpers/which, you might get 3.5" and actually need the trac bar/control arms/etc.

 

A little more back info to maybe help some, I'm already running a bb and the steering seems fine, no problems with bump steer etc. I understand why I need the tracbar but mostly I was just trying to figure out if I could get by without the tracbar for a while until I save the money for trac bars and eventually at least front lowers and rear upper control arms