The Rancho RS9000 shock has a 15-stage velocity sensing valve, plus a five-position ride adjustment knob on the shock body, the latter enabling you to vary compression and rebound damping while the car is stationary. (Compression damping controls the speed at which the wheel moves upwards.Rebound damping controls the speed at which it moves downwards, or rebounds, after shock compression. More damping slows the wheel movement, making the ride stiffen less damping speeds it up, making the ride softer.)
If you like the idea of “driving” your suspension, as you would drive the engine, transmission or brakes, Rancho supplies an in-car adjustor so you can finetune compression and rebound settings, while the car is moving. The system comes in two versions; a one-dial set-up where you adjust the damping on four shocks simultaneously; and a two-dial set-up where the front and rear shocks can be adjusted independently. The dials are actually air pressure gauges which register the change in damping on a scale.
The kit and air pressure adjustor and gauges can be fitted when the shocks are installed, or retrofitted. According to the national distributor (Auto Alliance, ph 02 9989 3989). RS9000 shocks cost about $170.00 each while the in-car kit retails for about $480. That may sound a lot, however, given that the Festo parts involved here are quite expensive in themselves, we reckon it’s good value for money. The retrofit kit is easy to install if you have the basic mechanical knowledge. Tim, who has the advantage of being a former aircraft technician, says the most difficult thing is deciding where and how to position the gauges and switches, and the manifolds and compressor.
The components are well designed and robust. Tim used a similar compressor for years to inflate the tyres on his dirt bike with no mechanical breakdown.
There is one way to make this adjustor better though, and that’s to make it quicker. In the standard installation every component is plumbed back to the pneumatic manifolds, A design that requires a lot of airline, and therefore a larger volume of air to fill those airlines.
We believe the Rancho kit should respond much faster to an increase in damping. The best way to achieve that is to fit T-pieces at key locations such as the diffs and gauges. This would reduce the length of airline by 50 percent and give a reduction in the compressor’s response time.
Installation tip 1: Tim sheathed the red Rancho airline in 4mm Festo airline for added protection. (Liquid soap s necessary for this task.)
Installation tip 2: When you remove the manual adjustors on the shock body, clean thoroughly behind them and then lubricate the ports with Festo pneumatic grease. This promotes good O-ring seating.
Installation tip 3: Spray all connections with soapy water to reveal any air leaks.
Installation tip 4: Tim will cable-tie conveyor rubber around air fittings to give them added protection from stone damage.