Hi,

I recently replaced my OEM shocks for my 98 Expedition 4x4. They were getting a bit soft at 93k miles. I researched a lot of shocks, but the ones that intrigued me the most were the Racho RSX shocks. One of the on-line suppliers advertised a 90 day ride satisfaction guarantee for these shocks. This same supplier also advertised Pro-Comp 9000 shocks; buy 3 get one free. That was tempting too, but I didn't know about Pro-Comp's reputation. So, I bought the RSX shocks. The RSX shocks provide good road feel, but are not harsh. The truck is very stable in hard braking and during turns, compared to the OEM shocks. Keep in mind that two of the original shocks were mostly dead, and the other two were rapidly on the way to mostly dead. Having said that, I am not sure how fair the comparison is. I also found a rough dirt road to see how the shocks handle rougher conditions. They were very supple and provided a surprisingly nice off-road ride. The new shocks fit perfectly, and I have no clunks or squeeks from the new shocks.

A double shock setup with stock springs may not produce the benefits you are seeking. The spring and shock(s) form a tuned mechanical system. Doubling the damping without changing the spring rate can degrade suspension performance. Adding shocks increases the bump force needed to get the shocks moving, thereby producing a harsher ride. Once they do start moving, dual shocks can reduce the used suspension travel on normal road bumps (because of excessive compression damping), thereby increasing ride roughness. Ideally, you want vertical wheel motion to absorb bumps. The springs take care of this. Then, once the spring compresses, the shock limits wheel hop by converting the spring's stored mechanical energy to heat. A properly tuned spring and shock combination provide a balance between ride comfort and handling performance. How you tune the pair depends on your driving environment and the vehicle weight.


Regards,

John

 

very good explination.