Got Mah Deuce pretty well stripped down. Took the old cab off today, and I'm getting ready to pull the engine. Removed the pitman arm so I can take the steering box out, and took a few measurements. I would have to take the leafsprings apart and cycle the suspension and steering to do this accurately, but I just wanted to get some rough numbers to support my position - that the stock drag-link is a major limitation when it comes to modifying the front suspension for better off-road performance.
The tierod-end at the knuckle is really the limiting factor, so that's what I focused on. First I made sure that the front wheels were pointed straight ahead. Then I removed the pitman arm from the steering box, and let the drag-link drop. Making sure that the drag-link was still aligned with the steering box when viewed from above, I made a note of the distance from the bottom of the framerail to the center of the tie-rod end (the one that's connected to the pitman arm). Then I lifted the drag-link up until the tierod-end at the knuckle made me stop, and making sure that the drag link was still aligned with the steering box, I made another measurement. The distance between those two measurements was only 9.5".
What this means is that in a best case scenario, the stock drag-link might allow for up to 9.5" of vertical suspension travel. But the tierod-end at the knuckle isn't anywhere close to binding when the suspension is at full compression, probably because it has to allow for articulation and steering. Depending on how much the front bumpstops actually compress, it looks like that eats up about 2.5" right there. And we can't actually let that tie-rod end bind when the suspension reaches full extension, because that could obviously cause that tierod-end to fail. So that leaves us with less than 7" of suspension travel. I'm talking about vertical wheel travel. Straight up and down. Not enough. Not for me.
The other problem with the stock steering arrangement is the relationship of the drag-link to the leafsprings. Specifically, I'm talking about the length of the drag-link, compared to the length of the front half of the front leafsprings, when looking at the vehicle from the driver's-side. Ideally, they should be close to the same length, and close to parallel. But the stock drag-link is only about 16.5" long, while the front half of the leafsprings is something like 24" long. This creates, and exaggerates, bump-steer.
So it's a matter of quantity AND quality. I could make some adjustments to the steering linkage, like tweaking the tie-rod to allow for more droop-travel. I'm sure I could get somewhere close to 8-8.5" by modifying the stock setup, but I think that's about the limit when it comes to what a person can do with the stock steering linkage. And I could push the steering box forward in order to lengthen the drag-link, which would help to reduce bump-steer. But we would quickly run into clearance issues, and the pitman arm and drag-link would be a lot more vulnerable. I'm guessing that's why the steering geometry is the way it is.
I'm sure that the engineers that designed these vehicles knew all about the compromises they were making, and I think they did a **** fine job. But I'm looking to go beyond their original intent, and improve on things a bit. Switching over to a fully hydraulic steering system means that the steering will never restrict the suspension in any way, and it will also virtually eliminate bump-steer, AND make Mah Deuce easier and more enjoyable to drive on/off-road. I hope this helps to clarify things for those of you that are questioning my intentions (and maybe my sanity).
