Rancho RS9000 Shock Absorbers

January 9, 2000

The Rancho RS9000 is probably the most well-known and sought-after shock absorber in the 4x4 world. Besides being a premium quality gas shock, its claim to fame is its adjustment knob that provides five settings for compression and rebound damping. Having never had the pleasure of owning a set, I was looking forward to testing a set that we recently installed on a Jeep TJ. Would the RS9000s live up to their reputation?

The test consisted of a couple of weekends spent driving the Jeep on various offroad terrain and on the streets and highways. Sometimes the Jeep's sway bar was on, some times we disconnected it. The shocks' valving adjustment was varied to see how they affected the ride and handling.

The primary question I had was whether or not the extra cost of the RS9000s was justified by the fact that the compression and rebound damping were adjustable. The short answer is a resounding YES for three very good reasons:

1. Most fourwheelers think the RS9000's main benefit is that you can adjust them for street and offroad terrain. That's true but their adjustability is much more useful than that. For starters, not all offroad terrain is the same. At one end of the spectrum are the thousands of kilometers of dirt roads in this province, many of which have been ditched with water bars (those ditches that run diagonally across the road to minimize water erosion). At the other extreme are the tight, twisting, rocky trails that demand a flexible suspension. In the first case, you want a fairly stiff shock to prevent from bottoming out your suspension when you hit a water bar too fast. In the second case, you want a soft shock that allows the wheels to follow the contours of the trail. With the RS9000s, you can set them for either terrain or anything in between.

   We had an opportunity to put our theory to the test when we went up to Clear Creek before Christmas. If you've ever been to Clear Creek, you know that getting to the trailhead requires a two-hour drive on a twisty, wash-boarded surface. We set the shocks to the #4 position to provide stable handling while making the fast run along the gravel road. We avoided the maximum firm setting, #5, because of the washboards. The shocks did an excellent job of keeping the TJ's body roll in check and we never bottomed out once even though we hit some of the water bars faster than intended. Once we reached the last few kilometers which was the rock crawling section, we set the shocks down to #1, the softest valving. The TJ was able to idle its way over the snow-covered rocks without lifting a tire. I was impressed with the versatility of the shocks.
    

2. Another

   The "tripod."

   benefit is for those of us who require a sway bar for the street but dis-connect it for the trail. It's not always feasible to re-connect the sway bar, either because you're parked on un-even terrain or because you're only going to be on the pavement for a short while, on your way to the next trailhead. In these situations, you can simply dial up the Ranchos to maximum stiffness and drive off. They won't limit body roll as well as the sway bar but they will make your vehicle much safer than if it had a regular shock absorber.

   One of the quirks affecting Jeep TJs with tall, soft suspensions, is what's known as the "tripod." The connected front sway bar, dis-connected rear sway bar and soft springs, in conjunction with the geometry of the rear track bar, can cause the driver's side front tire to lift in the air when accelerating hard in a left hand turn. We were hoping that the Ranchos would be able to curb this tendency. Unfortunately, the TJ still lifted its wheel even with the shocks set to maximum stiffness. Although the Jeep continued to lift its wheel, Jonathan reported that the Jeep felt more stable and didn't compress as much on the passenger side with the shocks on maximum stiffness.

   In retrospect, it's shouldn't have been too surprising that the Ranchos could not cure the problem. The only cure is to re-connect the rear sway bar. For a shock aborber to provide that degree of stiffness, it would result in an extremely harsh, bone-jarring ride which no one wants.
    

3. For

   Long travel, adjustable Ranchos are a perfect match for this very custom Suzuki.

   those of us who have custom suspensions, finding the right shock can time a time-consuming and costly process because we can't rely on the experiences of others to know which shocks will work best. With the RS9000 shocks, we can dial-in whatever damping we need, rather than swapping out different shocks looking for the right valving. This benefit also comes in handy when you're experimenting with different spring rates and configurations. It's no wonder that the majority of hard-core builders use RS9000s.

So there you have it, three very compelling reasons why I think the Rancho RS9000 shock absorber is worth the extra cost.

...lars