[markjohnson]

That's how "street"-type ladder bars work.....by binding up the rear suspension because of the two different arcs of the leaf springs vs. the ladder bars. Eventually, they WILL rip the spring perches off from the rear axle housing tubes. The only way to stop this is to cut off the stock rear axle housing perches and weld on leaf spring "floaters" onto the tubes. Unfortunately, these floaters then put a lot of stress onto the front ladder bar mount which isn't exactly very stout on these street-type ladder bars. I'm sorry if there's not a lot of good news in this answer but these are the reasons that you don't see these street type ladder bars on fast cars. A good set of quality traction bars has always been the best way to improving leaf spring suspensions with even a decent ride quality when you have the proper snubber gap.