I know the rules, they are very simple, when executed properly, provide near bulletproof steering that doesn't wear itself out no matter how much you use it offroad on big tires.
The rules are that the steering gear travels to the internal stops fully. When that happens, the next thing is the knuckle steering stops hit and stop the knuckle rotation at exactly the same time. After that is dialed in, then the assist cylinder is stroked to exactly match the rotation of the knuckles at the stops. Seems relatively simple but here is what happens that we have fought with on every big build until now.
The issue is always the same, you wind up with more travel one way than the other. So, you clock the pitman over one tooth and that just reverses the problem so now you have more travel and less travel with it just switching which knuckle hits first.
I have extensively played with making the pitman longer and shorter. That doesn't change the bias in the least, it just makes the problem more or less by how far one side stops and the other is short. Then we've played with the distance from the balljoint or kingpin axis where the draglink attaches. Again, just makes the issue more or less but does not change the bias.
After dicking with it some, I finally had an epiphany and came up with full understanding of what is going on and how to fix it. For clarity, I've managed to brute force them into submission through various things like bending the pitman over to one side or reaming the hole off center. I've even built mock up pitman arms that shift the draglink hole way off to one side, still a problem.
The answer is stupid simple. Just make the draglink longer or shorter. Sounds odd but if you cut the arm loose from the round splined slug and move it over to the side with less travel, that offsets the bias toward where you need it to be. In other words, if you need more travel turning right because the left side stop isn't touching yet and the right side is bottoming out preventing rotation, move the steering arm to the left side by making the draglink longer. Tack the arm to the slug and test again. It makes immediate results and you can see the change in bias very easily. I'm not going to tell you how to exactly build a pitman after since it requires some welding that your life depends on but the ONLY way to get it right in a fast and easy manner requires that you alter the length of the draglink to move the end of the pitman arm over on the splined slug without moving the steering wheel. Of course, this is all predicated upon the axle being centered at ride height and the steering wheel and steering gear being dead center.
The rules are that the steering gear travels to the internal stops fully. When that happens, the next thing is the knuckle steering stops hit and stop the knuckle rotation at exactly the same time. After that is dialed in, then the assist cylinder is stroked to exactly match the rotation of the knuckles at the stops. Seems relatively simple but here is what happens that we have fought with on every big build until now.
The issue is always the same, you wind up with more travel one way than the other. So, you clock the pitman over one tooth and that just reverses the problem so now you have more travel and less travel with it just switching which knuckle hits first.
I have extensively played with making the pitman longer and shorter. That doesn't change the bias in the least, it just makes the problem more or less by how far one side stops and the other is short. Then we've played with the distance from the balljoint or kingpin axis where the draglink attaches. Again, just makes the issue more or less but does not change the bias.
After dicking with it some, I finally had an epiphany and came up with full understanding of what is going on and how to fix it. For clarity, I've managed to brute force them into submission through various things like bending the pitman over to one side or reaming the hole off center. I've even built mock up pitman arms that shift the draglink hole way off to one side, still a problem.
The answer is stupid simple. Just make the draglink longer or shorter. Sounds odd but if you cut the arm loose from the round splined slug and move it over to the side with less travel, that offsets the bias toward where you need it to be. In other words, if you need more travel turning right because the left side stop isn't touching yet and the right side is bottoming out preventing rotation, move the steering arm to the left side by making the draglink longer. Tack the arm to the slug and test again. It makes immediate results and you can see the change in bias very easily. I'm not going to tell you how to exactly build a pitman after since it requires some welding that your life depends on but the ONLY way to get it right in a fast and easy manner requires that you alter the length of the draglink to move the end of the pitman arm over on the splined slug without moving the steering wheel. Of course, this is all predicated upon the axle being centered at ride height and the steering wheel and steering gear being dead center.
