Motion Ratio on Trailing arms
In the search for more travel it is tempting to put the shocks very far up the links in order to pull big numbers. As leverage increases on the shocks it can make them a lot more difficult to tune because the shocks quickly get too soft. Not only are they moving slower, but less of the force is getting to the chassis. Typical prerunners, U4 racers, and other vehicles with similar weight (650-1,000 lb/corner chassis weight) and running shocks in the 2.5 and 3.0 size should shoot for a motion ratio of 0.6 on the coilover, and 0.8 on the bypass, or less (higher numerically). Light weight vehicles can run more motion ratio, and vehicles with bigger shocks can run more (numerically less) motion ratio. This is not an exact science and there is a lot more to it than meets the eye. Most experienced chassis builders have it pretty well figured out. Another source of reference can be proven vehicles with similar weight and shock package which are running similar terrain. And of course you can always ask for our input when ordering shocks.