Menu

Home / Hydraulics

Hydraulics

Ram assist, full hydro, pumps and coolers

Big tires make steering work harder. Hydraulics can help, but only if the pump, reservoir, cooler and box are planned as one system.

Ram assist

DriverPassengerBox + pitman armAssist ram: axle to tie rodHoses from the boxTie rodDrag linkAssist cylinder
Ram assist: the mechanical linkage stays, and a cylinder between the axle and tie rod adds push.

A ram-assist kit adds a hydraulic cylinder that pushes and pulls the tie rod, fed by lines from the steering box. It takes much of the load off the box and sector shaft. The mechanical steering stays, so if the hydraulics fail, you can still steer.

Full hydraulic

Full hydraulic steering removes the mechanical connection: the steering wheel drives a valve and the cylinder does all the work. It's a stand-alone system that depends completely on fluid power. MotorTrend's hydraulic steering tech guide favors ram assist over full hydro for trail rigs that also see pavement.

Pumps and reservoirs

  • A pump's flow decides how fast the cylinder can move, and its pressure decides how hard it can push. Box and cylinder makers publish the flow and pressure ranges their parts are designed for.
  • A cylinder holds fluid as it extends and retracts, so the reservoir has to cover that volume. Assist and hydro kits often call for a larger remote reservoir.
  • A pump from a different era may need different brackets, pulleys and hose fittings.

Coolers and heat

Steering hydraulics turn work into heat. A power steering cooler does for the steering fluid what a radiator does for coolant. Some factory systems list a cooler as optional equipment, and assist and hydro setups that work hard off-road benefit from one. Mount it where it gets airflow and keep the lines away from the exhaust.

Fluid

Use the fluid your owner's manual or service information specifies, or the fluid your box and pump maker calls for in an aftermarket system. Service manuals specify a fluid type. The 2007 Wrangler JK manual, for example, warns that other fluids can damage the pump and system.

Planning an assist setup

  1. Start with sound linkage and a solid box mount. Hydraulics multiply force and show up weak parts.
  2. Choose a box with assist ports, or have yours ported by a shop that does it.
  3. Match the cylinder, pump flow and pressure to the box maker's recommendations.
  4. Size the reservoir, add a cooler, and route the hoses clear of heat and moving parts.
  5. Bleed the system as the kit maker describes, then check for leaks and clearance through full travel.

On 1994-2002 Rams, Dodge Off Road's Heavy Duty Steering Kit for 2nd gen trucks with a PSC box is an example of matching the linkage to an aftermarket box.

Dodge Off Road heavy-duty drag link and tie rod laid out on a shop floor
DOR heavy-duty steering linkage for 2nd gen Rams, laid out before install. See the kit.

Last reviewed 2026-10-19. General information only: verify with your service information and parts maker.