This picture shows a fully hydrostatic arrangement on the front end of Top Truck Challenger Dan Dibble's ASM rock buggy. In extreme situations, such as rock racing, this type of setup is superior. A POS double-ended ram is mounted high on the front axle. It's very important to get the steering geometry right when building a system like this.
Though the exact placement of the ram varies from axle to axle, there is one key consideration to remember when mounting a double-ended ram: Angle of deflection. The angle of tie-rod deflection is critical to the life of the ram. Too much deflection can cause extreme shaft side-loading and, ultimately, ram failure. The illustrations at right demonstrate an ill-positioned ram as well as a well-balanced mounting method for double-ended ram tie-rod deflection.
Full Hydro
Howe, PSC, and POS all build great full hydraulic systems for 4x4 enthusiasts. However, when you focus in on the details of each setup, you'll find each system is very different, and depending on what type of 'wheeling you plan to do, each system has strengths and weaknesses. For instance, Howe builds a large majority of the steering components found on high-speed Baja racing vehicles, one area where failures can cost lives. Though they do offer a variety of systems for rockcrawlers. Howe made its name in the desert racing community. POS, on the other hand, is a niche-focused company specializing only in fully hydraulic systems for extreme rockcrawlers and buggies. PSC Motor Sports covers all the niches of the industry, though some would argue that its mainstay is professional rock racing. In any case, all three companies have very nice components for just about every budget level.
Hydro Assist
West Texas Off Road, Howe, and PSC all make awesome hydro-assist kits. These hydro-assist setups retain the mechanical functionality of the OEM steering system. For dual-purpose trail rigs, these types of setups are probably the best options. We recently installed the West Texas Off Road system on our project Teal-J. We're very happy with the its performance thus far. Likewise, the Howe ram-assist system we recently installed on our Baja Bomber project Dodge Ram is also working out great. As of press time, we hadn't yet tested the PSC Motor Sports hydro-assist kit, but we did receive the system and will say it's probably one of the most complete kits on the market, leaving only two hoses for the consumer to source.
Full Hydro DOT Legality?
Someone started a rumor about fully hydraulic steering being illegal for use on the highway. This is not true. We contacted the U.S. Department of Transportation and asked about the rules on hydraulic steering systems. We were told that any rules prohibiting the use of fully hydraulic steering systems in the automotive aftermarket would fall under local laws. We suggest you check with your state's local transportation authorities if you question the legality of hydraulics.
•Pure synthetic oil reduces friction and heat. Heat is the enemy, so it's always a good idea to use synthetic fluid.
•It's very important to bleed all the air from your system before starting your engine and running the pump for the first time. The inside of the pump has several metal-on-metal moving parts that can be damaged if operated without oil.
•All components of a hydraulic steering system should be matched in regards to flow, pressure, and volume. Those who choose to substitute parts of the system with unmatched components will likely encounter undesired results.
•The pulley that drives the power-steering pump should be sized according to the specified rpm limits of the pump. If your engine is capable of overdriving the pump, a larger pulley should be used to slow it down.