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Xj Hydro Assist Problems

jimbo92

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99 xj with waggy 44s. Acquired it mostly built a few months ago. Has some sort of heavy duty steering, and a psc hydro assist with the psc box. Finally got around to wheeling it yesterday and before I wheeled it, it drove beautifully. Left the off-road park and immediately almost put it in the ditch. Had to drive slow and fight it the whole way home. Steering no longer returns to center and requires CONSTANT feedback. It will get so squirrelly it mimicked the feeling of out of control trailer away.

Couple items: I smacked the tie rod into a rock and it made the tie rod roll forward making the ram point downward. See pic.

When I remove the power steering reservoir cap it makes a “psshhh” sound like opening a soda.
 

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Bebop

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Fix the track bar and try again
 

jimbo92

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The bolt going through the drag link into the tie rod end was a hair loose. That got rid of the big scaries (need to re align it) but still don’t know why this hydro assist doesn’t center. Is that an inherent trait? New to hydro. So far I hate it. Fairly slow to respond to input. I’ll take my whining pump in my explorer any day. The driving characteristics are much nicer.
 

Byro

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Fix the tie rod. The ram is in a bind.

Also the 4.6” PSC pulley is the way to go. It will require a shorter belt.
 

Mike Honcho

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Fix the tie rod. The ram is in a bind.

Also the 4.6” PSC pulley is the way to go. It will require a shorter belt.

I tried the small psc pulley and got nothing but cavitation/ whine.

If you do want the small pulley I have one and a new belt just sitting.
 

jimbo92

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Fix the tie rod. The ram is in a bind.

Also the 4.6” PSC pulley is the way to go. It will require a shorter belt.

That was the first thing I did when I got home and caught it. I should have clarified that.
I tried the small psc pulley and got nothing but cavitation/ whine.

If you do want the small pulley I have one and a new belt just sitting.

Yeah I’ll give it a shot. I’ll send you a PM.
 

RunningProblem

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Fix the tie rod. The ram is in a bind.

Also the 4.6” PSC pulley is the way to go. It will require a shorter belt.
I don’t see how the ram is in a bind. In the photos it remains parallel with the axle so the travel shouldn’t be bound up, right? Is the bind caused by the tires being tied in bad due to the bent tie rod?
 

Byro

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I don’t see how the ram is in a bind. In the photos it remains parallel with the axle so the travel shouldn’t be bound up, right? Is the bind caused by the tires being tied in bad due to the bent tie rod?
2nd pic, rolled over like that it is definitely out of plane and would cause a bind.


I would also check that the shaft isn’t bent.
 

FordFascist

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It's a pretty common problem to have the ram rotate the tie rod (usually on extension) which in your case is turning left. When that binds, you lose all your hydraulic force in that direction. When you turn the opposite direction, you lose the hydraulic advantage to the motion of the tie rod rotating back. This is what creates the dead spot and the feeling of no steering control. Check the ram to make sure it's not bent.

There are a couple of fixes for this:
  1. Connect ram to the knuckle directly
  2. Run a double-ended ram
  3. Create a tie rod anti-rotation solution

I fabbed a tie-rod anti-rotation bracket because this happened to my GPW so much:

1667955998232.png


1667956033656.png


1667956047498.png
 

RunningProblem

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Byro i thought photo 2 was a bent tie rod. You, and FordFascist, are saying the ram rotates the tie rod when he turns. it’s pushing the ram forward of the axle instead of parallel to the axle. Right?
 

FordFascist

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Byro i thought photo 2 was a bent tie rod. You, and FordFascist, are saying the ram rotates the tie rod when he turns. it’s pushing the ram forward of the axle instead of parallel to the axle. Right?

The tie rod is never strictly parallel to the ram so there is always some component of force perpendicular to the tie rod that will try to rotate it. Unless you anchor the tie rod you will have some sort of rocking. It's also worth noting that this TR clearanced to not hit the diff cover, so its got more leverage to rock than that of a straight tie rod.

1667959684485.png
 

The Freeak

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All those bends in the steering linkage isn't optimal... can the tie rod be straight?
Can you move the assist cylinder to act directly on a knuckle?
 

jimbo92

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Sorry just now getting back to this. The second pic was immediately after wheeling. The first pic is how it is currently. Brought it to work and aligned it, its better, but still nowhere near what it was. Going to check for a bent ram.
 

jimbo92

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To clarify the ram does not push the tie rod forward. Running it into a rock pushed the tie rod down.
 

Drillsmoke

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Aside from the pre-bent tie rod, the way the ram is mounted is definitely not ideal either. Ideally your ram mount on a tierod is as close to the end of the tie rod as possible, as this puts less bending forces on the rod. I would try to re-do the ram mount to where maybe it mounts to the diff cover and pushes towards the driver knuckle, or rig up a mount on the pass side that pushes to the knuckle or a mount on the tie rod that is as close to the knuckle as possible. I had a dana 44 w/ ecgs steering arms, 1.5" tie rod and a ballistic 1/4" wall diff cover and was able to run a perfectly straight tie rod w/ a ram attached towards the end. Any tie rod that is bent into a "u" is gonna have an inherent amount of rotation in it if you are pushing on the center of the rod.
 

BigWheel

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That got rid of the big scaries (need to re align it) but still don’t know why this hydro assist doesn’t center. Is that an inherent trait?
My hydro assist doesn’t really center either, there’s a lot of sawing the wheel when I’m out. My steering is also slow especially at lower rpms, but that doesn’t bother me too much, it still has the power to turn the wheels. I opted for the bigger bore steering box so that’s partly why the steering is slower.
I think that if the ram was set up like in the second pic, it would definitely bend when out wheelin and getting banged around. I think the way you mounted it in the first picture is correct but the ram or steering box might be damaged from the last outing. Maybe. Rod ends just might be shot?
 

The Freeak

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Aside from the pre-bent tie rod, the way the ram is mounted is definitely not ideal either. Ideally your ram mount on a tierod is as close to the end of the tie rod as possible, as this puts less bending forces on the rod. I would try to re-do the ram mount to where maybe it mounts to the diff cover and pushes towards the driver knuckle, or rig up a mount on the pass side that pushes to the knuckle or a mount on the tie rod that is as close to the knuckle as possible. I had a dana 44 w/ ecgs steering arms, 1.5" tie rod and a ballistic 1/4" wall diff cover and was able to run a perfectly straight tie rod w/ a ram attached towards the end. Any tie rod that is bent into a "u" is gonna have an inherent amount of rotation in it if you are pushing on the center of the rod.
Exactly.
I'll add that if it were my application, I'd revise the assist cylinder mounting so the cylinder body is mounted to the axle tube/ diff cover, and the active (shaft) is mounted to the tierod, just inboard of the PS knuckle, with the bracket on the rear of the bent tube, thus applying force inline with the movement of the tierod and the cylinder.
 

Drillsmoke

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Also, providing that everything is working properly and designed well, the system should self-center do a degree (just not as well as a factory linkage steering). I have had three different assist setups, both on dana axles and toyotas and they all had very good road manners. They are going to be slower than most non-hydro setups, but you get used to that if everything else is working as it should.
 

jimbo92

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Finally got around to ripping it apart to see what was going on. The piston is bent. Going to contact psc about a replacement. Thank you all for the input.
 

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