This is needed because the upper arm is a stamped steel piece, and the bushing needs the support of the steel to work properly. The attention to details like this set Whiteline bushings apart from your typical urethane replacement parts.
These bushings influence toe and camber change under load. The bushings include new steel sleeves like all Whiteline bushings. The sleeves are zinc plated for lower friction and to resist corrosion for a long life.
In this picture, you can see an important design feature that all Whiteline bushings share. At the ends of the center hole of the bushing, you can see a raised area. This acts like a lip seal to keep water and dirt out and grease in.
You can also see the diamond groove texture on the inside of the bushings’ hole. The grooves help retain the grease where it is needed and also serve to reduce friction. No other urethane bushings have these features to our knowledge.
The longer bolts are used with shims to move the rear upper control arm outward, thus reducing camber. With shims, there is no possibility of the adjustment slipping.