I’m frequently asked why I chose to run a body lift on my 3rd gen 4Runner, and why I design a lot of my stuff to be used with a 1-1.25″ body lift, and while answering those questions again today, I thought it made sense to explain my reasoning here for everyone’s benefit:
for me, the 1.25″ body lift is all about travel, clearance, and keeping a low COG.
the way I see it, IFS travel is limited by 2 things – the effective operating angle of the CV joint, and overhead clearance (body interference).
on a truck with stock suspension, the axle angles are close to horizontal so 1/2 of its travel is downward, limited by the angle at which the CV joint binds (assuming enough overall shock length). the uptravel, on the other hand, is usually limited by the body well before the CV joint binds in that direction (assuming the collapsed length of the shock is appropriate).
when IFS is raised by using taller springs, the axles are angled downward at lifted ride height – so now the downtravel is reduced (CV joint still binds at the same angle it always did), and with the addition of larger diameter tires, the uptravel is reduced as well because the larger tire interferes with the body sooner – so the usable travel is now less than that of the stock setup.
on my 4Runner, I used a 1.25″ body lift in conjunction with a shorter overall suspension lift to retain as much usable travel as possible. my axles are closer to horizontal at ride height than they would be with a taller suspension lift (for maximum down travel) and because of the body lift the top of the wheel well is higher, allowing the same maximum possible uptravel as a stock truck would have, even with the 35s I run (after generous firewall tubbing, of course) – in the rear, that additional wheel well height allows me to stuff the 35s up to the factory bump stop as well, without any tubbing.
the body lift height I chose is also allowing me to rotate/clock the transfer case to clear the frame rails for ground clearance – and remove the low-hanging crossmembers – to get a flat belly without cutting into the floor. the break-over clearance of a flat belly on the 3rd gen is equivalent to that of a 4” or so suspension lift, but without the COG penalty since the frame & drivetrain (heaviest parts of the sprung weight of the vehicle) remain the same height relative to the ground.
– so basically, a 2” suspension lift and a 1” (1.25” in my situation) body lift nets more suspension travel and lower COG than that of a 3” suspension lift, with the break-over clearance of a `4” suspension lift.
(as a bonus, the body lift makes it possible to tuck the Ford F-150 tank up into the frame rails behind the axle and provides room for a dual triangulated 4-link in the rear with a proper upper link tower without cutting into the cabin area.)