Hydro Steer Powersteering reservoir

Several years ago when I dealt with a Jeep with hydro assist, there was a problem with the volume of the reservoir on the PS pump. Unlike the stock system, the volume of fluid in the system varies with the position of the hydraulic piston, due to the volume displaced by the rod in the cylinder. At one extreme, there was practically zero in the reservoir, while at the other extreme the fluid was puking out the cap.

Who has experience with this and has found a good solution? I am running a 1.5" piston with 8" throw. My rig is an early Renix running a stock pump on a Dakota box with a D44.

Is there a better pump (storage volume/flow rate) that fits with minimal hassle? While I have all the tools to do virtually any modification, I do not have the time.

I had a similar problems with my hydro assist. I was thinking that I should have rotated the ram around so that it was pushing in the oppisit direction.

Here's my thinking. When I went to full hydro I had to get a bigger ram but the fluid level change was quite a bit less. I was thinking I may have had the ram oriented such that when turning the direction that needed all the fluid the ram was extending and the piston in the box was moving in such a way to need more fluid. Then when turning the other way the piston in the box was compressing and so was the ram.

With my full hydro I'm running a 2.5" bore vs a 2" bore with assist but the fluid change in the box is probably less then half that it was with hydro assist.

jmop said:

I had a similar problems with my hydro assist. I was thinking that I should have rotated the ram around so that it was pushing in the oppisit direction.

Here's my thinking. When I went to full hydro I had to get a bigger ram but the fluid level change was quite a bit less. I was thinking I may have had the ram oriented such that when turning the direction that needed all the fluid the ram was extending and the piston in the box was moving in such a way to need more fluid. Then when turning the other way the piston in the box was compressing and so was the ram.

With my full hydro I'm running a 2.5" bore vs a 2" bore with assist but the fluid change in the box is probably less then half that it was with hydro assist.

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Intersting thought. I have the stock reservoir on my AGR pump on the XJ with ram assist and don't have any fluid volume issues. However, compared to Tom's, my ram is 1 3/8" with a 7.25" throw.......maybe just enough to make a difference. For the record, mine is attached to the inside of the track bar axle mount and extends to the driver side. I don't remember if it was on the XJ or on the buggy, but I remember over filling the reservoir when it was in the position that topped out the fluid level, and put a hose on the cap vent (nub that extends on most PS caps) to catch any fluid that vents. I put a loop in the hose to catch the fluid so it can drain back into the vent.

On the buggy, I now have a seperate reservoir, and the ram is 8" x 1.75". But, the previous ram was 8" x 1.5" and it worked fine with the stock pump reservoir. Really, if the shafts of the various size cylinders are the same diameter, the cylinder size wouldn't matter since the volume of fluid displaced by the shaft would be the same. I know there are plenty of people running assist with the stock reservoir, and there are plenty running with remote reservoirs.

the fluid goes from one side of the piston to the other.your only real advantage is more volume will keep it cooler

markg said:

the fluid goes from one side of the piston to the other.your only real advantage is more volume will keep it cooler

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Except you have to take into account the fluid displaced by the rod. It can be substantial causing the high and low levels in the resivoir.