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Hydro-assist ram causing wandering

LScout800

LScout800

LS Powered Tractor
Joined
Jun 10, 2020
Member Number
1937
Messages
456
Loc
CA
I have hydro-assist steering, and it works great for everything but the street. I have aligned my scout, used constructions lazers to square up both axles and put them in line with each other, I have my steering set up so that it steers the same amount in both directions, and I have the front tires towed in about 1/8". My caster is set to about 6 degrees. All steering components and wheel bearings are new. The truck wanders pretty bad. Going down the highway it is very difficult to keep it in its lane past 35-40 mph. It does not track down the road straight, and you have to constantly correct it one way or the other. I took off the ram, and it seemed to track better, although taking the ram off essentially took away my power steering so I did not get to test it much like that since it was hard to drive. Still trying to figure out what's up with it, anyone have similar issues?
 
Wondering what ram, pump, steering box you are using? King pins or ball joints? U-joints in axle fresh or...?
 
ridenby said:
Wondering what ram, pump, steering box you are using? King pins or ball joints? U-joints in axle fresh or...?
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Pre super duty ford ball joint 60, jeep zj steering box, stock gm 5.3 steering pump, ball joints, u-joints, tie rod ends have all been replaced. The ram is a surplus ram 8 inch travel. Believe it is a 1.5 inch diameter. I used the kit from DIY 4×4 to tap the box, and 3/8 hydraulic line.
 
When I’m doing driveway alignments I always go 1/4” toe in and 7-9* positive caster. A little more toe may be what you need, it’s surprising how a few degrees will really change things.
 
Byro said:
When I’m doing driveway alignments I always go 1/4” toe in and 7-9* positive caster. A little more toe may be what you need, it’s surprising how a few degrees will really change things.
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I will give that a shot.
 
Sterlingfire said:
Not to imply you to be dumb or anything, but do you know what positive caster is?
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Positive caster means the c is rotated clockwise when you look at it, or the upper ball joint is behind the lower if looking at it from the side. It has 6 degrees of positive caster. At least I hope that is what positive caster is and I don't look like a dumbass.
 
LScout800 said:
Positive caster means the c is rotated clockwise when you look at it, or the upper ball joint is behind the lower if looking at it from the side. It has 6 degrees of positive caster. At least I hope that is what positive caster is and I don't look like a dumbass.
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You are correct. Just wanted to be sure.
 
When doing tape measure alignments (the only kind I do) I shoot for 1/4-3/8 toe in and 6-9 degrees caster on 40" tires. Anywhere in that range seems to work good for me.

Im thinking at 1/8 to in you are to close to 0... and it would be easy to be off 1/8
 
20221128_220540.jpg

Got some of those ruff stuff cure pucks ordered to see if it can help solve my issue.
 
I have the ram lined up as much as clearances will allow. I tried to get it to push the tie rod as much as possible instead of twisting it. It is in line as it could be before contacting the drag link under full lock.
 
My guess is the inverted T style steering and the way you have your ram mounted gives you tons of tie rod roll, creating a dead spot in the steering while going straight. You can start by trying to mount the ram directly behind the Tierod, then maybe look at a proper cross over style steering. Possibly your steering box is worn out as well, the steering gear backlash can be tightened up a bit and might help wandering a bit. Probably a combo of everything slightly not right....
 
I'm running the 1.75 x 8.75" PSC ram don't have none of those issues. 6 deg caster.

However leafsprung. 1/4" toe is also what I'm running on 40s.
 
Mattygwheeler said:
My guess is the inverted T style steering and the way you have your ram mounted gives you tons of tie rod roll, creating a dead spot in the steering while going straight. You can start by trying to mount the ram directly behind the Tierod, then maybe look at a proper cross over style steering. Possibly your steering box is worn out as well, the steering gear backlash can be tightened up a bit and might help wandering a bit. Probably a combo of everything slightly not right....
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How much play is acceptable? I have about an 8th turn on the steering wheel before the tires move. All my other vehicles have about the same amount. When I checked the box this morning I saw it was starting to leak around the input so it is probably time for a rebuild anyways.
 
I'd get someone to turn the wheel while you're under there watching what happens. Also put a hand on components and see if you can feel a clunk or movement as they pass through the dead band.

Then remove the ram and see what changes.

I bet the main culprit is the ram angle, but you might find that there's a ton of play in the box, or something else weird.
 
Caster is often a big issue with what you are discribing. I have done lots of playing with toe and found it not to be nearly as important as caster. 6 degrees should be enough, but it’s definitely not too much. Are you sure you have 6? I’m thinking that less than perfect measuring equipment puts your caster at slightly less than 6. If you get any lift from excellerating, you lose another degree. The difference of 4-5 compared to 8-9 is dramatic.
 
Gunwalls_Buckthorne said:
Tires might be junk….
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Hope not. They are brand new falkens. I had them mounted and balanced by a local tire shop that I have been using for years. I have been making adjustments all week will see how it drives tommarrow.
 
Set the toe in more and set the caster back a couple degrees more. It drives better. Now it just feels like its "pinballing" when going down the highway. Took two videos of the front end turning back and forth. One with the ram on and one with it off. My tiered rotates in both, so it is die to the drag link. I ordered some parts to fix it on Friday, and they have still not arrived... Trying to upload videos but I keep getting error codes.
 
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Its Bump Steer. Everything you are describing is pointing towards drag link and track bar Geo. Everything with a steering box and a track bar have some amount of bump steer it is just how bad.

The cure bushing will help the dead spot. Really soft suspension set ups and no sway bar make it worse.

Equal length is second to parallel. Flatter is best at ride height. You are at a decent angle a drive height. Your angles have to be almost perfect like with in half a degree. What are your current angles?

Cool build by the way!
 
LScout800 said:
Set the toe in more and set the caster back a couple degrees more. It drives better. Now it just feels like its "pinballing" when going down the highway. Took two videos of the front end turning back and forth. One with the ram on and one with it off. My tiered rotates in both, so it is die to the drag link. I ordered some parts to fix it on Friday, and they have still not arrived... Trying to upload videos but I keep getting error codes.
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upload to youtube then paste a link.
 
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