Full Hydraulic Steering II

 

   
 
 

Full Hydro Steering - Part II

I did a write up on my first attempt at a full hydro steering setup back in 2003.  Be sure and check out that article for the pros & cons of full hydro steering.  This write up shows how I did my latest setup with the biggest difference being the addition of a double ended ram and a new way to vent the reservoir that I picked up from an online bulletin board.  

Why a double ended ram?

The biggest reason to go with a double ended ram is because it has the same fluid capacity on each side of the piston so the number of turns lock to lock will be the same, just like a normal steering box. Also, load reactive steering valves are not designed to work with single ended rams so you may experience some wander (you also void the warranty on the valve). In my case the double ended ram was much easier to mount than the single ended ram so the extra cost was worth it. Actually, with a single ended ram I would have had to completely change my link design and use a panhard bar due to space constraints.

Plumbing

The heart of your system is the steering valve and that's where I will start.  I mounted the valve where a steering box would normally go to keep the high pressure lines away from the passenger compartment and to minimize the distances between the various components on the low pressure side. The valve is connected to a TC style Saginaw pump via a -6 (3/8ID) line.

From the valve I ran -6 hi-pressure lines down the links to the cylinder ports.  Hose length is not a concern on the hi-pressure side.

On the low pressure side hose length should be kept under 24" between components to avoid restrictions.  In addition, you should increase the hose ID after each component, again to avoid restricting the flow. So in my case I ran a -8 (1/2" ID) hose from the valve to the cooler (first picture above), then from the top of the cooler I ran another -8 hose to the filter.  Notice how short the hoses are. 

From the filter I bumped up the hose size to a -10 (5/8" ID) which runs to my reservoir. The reservoir feeds the inlet of the power steering pump via another -10 hose, never use anything smaller. To vent the reservoir I installed a fitting and some 1/4" air line which loops under the transmission to a small vented catch can on the other side of the engine bay.  I made the catch can from some 1.00 x .120 wall tubing, capped both ends and then drilled and tapped them for fittings.  I used a hose barb on top where I attached a small K&N filter, the bottom fitting takes the 1/4" air line from the reservoir. 

A little about the reservoir.  This is a homemade unit made by my buddy Randy.  It is approx 6" in diameter and 8 " tall.  We installed a baffle that sits just under the top.  The baffle has a 3/8" hole drilled in the center to help keep the pump from sucking air when off camber or upside. I am a firm believer in having lots of fluid capacity in your hydraulic system.  Having more fluid in the system helps keep the system cooler which makes the fluid last longer. I have seen a lot of people use the small circle track reservoirs.  The big problem with these is they are not designed for off camber situations and many times their feed port is too small (remember you want at least 5/8" ID). On my reservoir the fluid is fed in from the side about mid level then exits on the bottom.  I also installed a small valve to make it easy to drain the system if I need to service it or replace a component,

There are lots of ways to mount the steering ram so I won't go into that here.  Just keep in mind that the angle of the steering linkages changes as you steer so you may get to a point where you bind your links.  That angle also effects how much stroke you will need from your cylinder.  In my case I ended up using about 6.75" of stroke so I had to limit the rams throw by installing some shaft collars behind the clevis blocks on the cylinder. 

The stock D60 knuckles are not designed to run a high steering arm and the 4 bolts that hold the arm in place can easily work loose. I mounted my ram so I could spread the steering load between the upper steering arms and stock tie rod mount on the knuckles.  If you do this make sure you use a welding rod designed for dissimilar or cast metals (typically a high nickel content rod) for attaching anything to the knuckles.  I tried using my mig but the welds broke after a few runs and it looked like the material from the mig wire and knuckle did not mix at all. 

If you want more in depth information on this topic, check out this article on the Pirate 4x4.com website.