Hydro steering

1stgenxxx

1stgenxxx

Well-Known Member
Joined
Dec 19, 2005
Location
Hudson
The steering on my Sami works but doesn’t have the power that I think it should. It really sucks when I get it in a bind and feels no stronger than a stock power steering.
Trail gear pump
Surplus center 2x8 double ended ram (limited)
Not much info on the orbits but I can pull the PN later. It’s 2.5 turns lock to lock. I put a pressure gauge on the high pressure line coming out of the pump and this what I saw cycling the steering back and forth. Any input?
 

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Not stronger as in it stalls? Or you have a heavy wheel feel?
Is the cylinder actually a 2 inch bore?
 
Yes the cylinder is 2” bore. If I cut hard left on the trail I have to turn the wheel pretty hard. It almost feels like the fluid is bypassing instead of being used to turn (if that makes sense). In my mind I though a 1600psi pump would use all 1600 no matter how far you were turning the wheel.
 
I’m gonna rebuild the pump next week ans see if that helps.
 
Think you may need to put a larger ram on it. Those surplus center rams have a larger rod than that of PSC or TG. The 2" bore with 1.25" rod gives you an effective piston area of 1.914 in^2 which at ~1600 psi would net 3063 lbf out of the ram. Where as a 2.25" bore with 1.125" rod ram gives you an effective piston area of 2.98 in^2 which should work out to ~4771lbf.

Now @paradisePWoffrd hit a good point too. Flow makes quite a difference in how responsive the steering will be. Which if the lines are undersized it can give you that heavy steering wheel feel.

I'm not sure if I'd go rebuilding the pump just yet, that pressure gauge did exactly what it should have done. You're only going to get as much pressure as the system needs. No load = low pressure, high load = all the pressure.
 
Chris_Keziah said:
Think you may need to put a larger ram on it. Those surplus center rams have a larger rod than that of PSC or TG. The 2" bore with 1.25" rod gives you an effective piston area of 1.914 in^2 which at ~1600 psi would net 3063 lbf out of the ram. Where as a 2.25" bore with 1.125" rod ram gives you an effective piston area of 2.98 in^2 which should work out to ~4771lbf.

Now @paradisePWoffrd hit a good point too. Flow makes quite a difference in how responsive the steering will be. Which if the lines are undersized it can give you that heavy steering wheel feel.

I'm not sure if I'd go rebuilding the pump just yet, that pressure gauge did exactly what it should have done. You're only going to get as much pressure as the system needs. No load = low pressure, high load = all the pressure.
Click to expand...
I'm confused on your rod and bore statement. Are they not one in the same? Cylinder diameter equals bore? Or is the piston machined in a step? Which holds the seals, bushings and such.

I think I answered my own question in my head but I've not torn one down.
 
BF7EA748-85CD-4B99-96A3-7DF1EAD57542.png
 
He has a double ended ram, so rod diameter should have zero effect on steering because the pressure side is the 2” bore side of the ram.
 
I’m certain that I ordered a 2x8 double ended ram. I measured the rods and they’re 1.25…not sure how to measure the cylinder bore without taking it apart. I thought that 2” rams worked well for full hydro. The 2.5 and 3” rams are pretty new to me.
 
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rockcity said:
He has a double ended ram, so rod diameter should have zero effect on steering because the pressure side is the 2” bore side of the ram.
Click to expand...

Incorrect. Rod diameter will 100% play into it as a larger rod diameter, with consistent ram bore, will decrease the surface area the fluid can push, thus decreasing output force. The steering force will be equal in both directions with a double ended ram but not with a single ended.

If there is an issue with turning one direction and not the other, the areas to check would be binding in the tierods/ends throughout travel, restricted/limited fluid flow, limited fluid pressure, or internal leak in steering valve. Also, one thing that will certainly affect full hydro steering, or any steering honestly, is the phase of the axle shaft u-joints if a spool or welded spiders are used. I've run into this issue myself and simply getting the axle shafts in phase significantly helped. Another commonly overlooked item is the pressure and feedline hose sizes. What size lines are you running?
 
rockcity said:
He has a double ended ram, so rod diameter should have zero effect on steering because the pressure side is the 2” bore side of the ram.
Click to expand...

The rod goes all the way through the cylinder body, that's what makes them so nice and have the same steering effort left or right. You have to deduct it from your working pressure.
 
adamk said:
Incorrect. Rod diameter will 100% play into it as a larger rod diameter, with consistent ram bore, will decrease the surface area the fluid can push, thus decreasing output force. The steering force will be equal in both directions with a double ended ram but not with a single ended.

If there is an issue with turning one direction and not the other, the areas to check would be binding in the tierods/ends throughout travel, restricted/limited fluid flow, limited fluid pressure, or internal leak in steering valve. Also, one thing that will certainly affect full hydro steering, or any steering honestly, is the phase of the axle shaft u-joints if a spool or welded spiders are used. I've run into this issue myself and simply getting the axle shafts in phase significantly helped. Another commonly overlooked item is the pressure and feedline hose sizes. What size lines are you running?
Click to expand...
back story...
when I bought the rig it had some very terrible mud truck hydro steering that was grossly undersized. The orbital was tiny tiny. The hoses were too small -4 pressure lines and -6 feed) and it felt like I was driving with regular power steering. The only plus was a PSC single ended ram and trail gear pump.
I used up some parts I had laying around.
Orbital
-6 hoses from pump to orbital and orbital to ram
-8 or 10 feed (ill have to check)
heat sync style cooler
2x8 ram
This is on a sami with a 3rz, toyota axles, welded front diff.
 
1stgenxxx said:
back story...
when I bought the rig it had some very terrible mud truck hydro steering that was grossly undersized. The orbital was tiny tiny. The hoses were too small and it felt like I was driving with regular power steering. The only plus was a PSC single ended ram and trail gear pump.
I used up some parts I had laying around.
Orbital
-6 hoses from pump to orbital and orbital to ram
-8 or 10 feed (ill have to check)
heat sync style cooler
2x8 ram
This is on a sami with a 3rz, toyota axles, welded front diff.
Click to expand...

I would highly suggest a -8 from pump to orbital and -12 feed. My initial setup for full hydro I undersized the lines because I was using a resi, pump, and lines I already had. First thing I found was the axle shaft ujoints not being in phased (using a spool) caused tremendous binding so I corrected that. That helped significantly but steering was still very slow and, at times, very difficult. I then called PSC to pick their brains as they are far more an expert than I and followed their suggestions. I switched to a larger resi, feed line, and pump to orbital line and that was the final solution for me.
 
adamk said:
I would highly suggest a -8 from pump to orbital and -12 feed. My initial setup for full hydro I undersized the lines because I was using a resi, pump, and lines I already had. First thing I found was the axle shaft ujoints not being in phased (using a spool) caused tremendous binding so I corrected that. That helped significantly but steering was still very slow and, at times, very difficult. I then called PSC to pick their brains as they are far more an expert than I and followed their suggestions. I switched to a larger resi, feed line, and pump to orbital line and that was the final solution for me.
Click to expand...
I remember now. Its -10 feed because I had the leftover fittings. The axles are birf joints so they should be ok. It doesnt have any hesitation turning when on jackstands. I ordered a rebuild kit for the pump so I'll start there. I tried calling trail gear tech support but I was on hold forever and then gave up.

also...I made sure to bleed the system multiple times and I never get any pump whine.
 
If you turn the orbital fast and it gets hard to turn, but fine when slow; flow volume is an issue. Either the pump needs rebuilt or is too small, or the lines are too small.
 
paradisePWoffrd said:
If you turn the orbital fast and it gets hard to turn, but fine when slow; flow volume is an issue. Either the pump needs rebuilt or is too small, or the lines are too small.
Click to expand...

The hard steering happens even when I turn slow. I'm going to rebuild the pump first. I will then change to a -8 from the pump to the orbital.
 
1stgenxxx said:
The hard steering happens even when I turn slow. I'm going to rebuild the pump first. I will then change to a -10 from the pump to the orbital.
Click to expand...
FIFY

Can't see your video, but what I can say is that I had a Samurai with a TG pump (same as you), plumbed with all AN6 lines (and a -10 feed) and it was tunring the tires wihtout any problems at all. On top of that it was 4 wheel steer, and you could turn both rams without any issue.
 
Guarantee its a bad pump. TG is a solid 75% shot at a bad pump and 25% shot of a good one. Same for psc as far as tc style pumps go. After an endless amount of money I spent on their pumps, the 1989 jeep cherokee tc pump from the auto parts store fixed it. And its a whole $50 at auto zone. You already have the pulley and the pressure port fitting to switch over to it, just have to figure out the return.
 
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