fordtech said:
actually he wont get bumpsteer, not at least how we with stock style steering are use to it. He will get a change in toe on both tires in opposite directions (mostly toe in on both sides). As his suspension moves the inner tie rods will move in an arch effectively shorten pulling the tire in toward the rack.
A traditional inverted y or drag link style is going to move the tires in the same direction (one in, one out, vice-versa), thats what causes bumpsteer. His issue would feel 'different' and will cause weird handling and steering over rough roads compaired to the traditional setup, and eventually wierd tire wear. Probably not 'felt' in the wheel as a kick, or a sudden jerk in a direction like bumpsteer.
That is exactly right, and was actually one of the considerations when deciding to go with the rack. As a matter of a fact, on my first test run, I had set the toe in ever so slightly, thinking that like everything else, the tires would naturally try to toe-out while being pushed down the road. Bad Idea! and hopefully my ONLY EVER experience with death wobble. holy crap I wasn't even IN the truck when it happened, I saw the whole thing 3rd person and and those shorts are in the trash, I assure you. when a solid axle enters into extreme toe-in scenario.... they begin to "skip" down the road, one after the other, because they are both trying to turn into one another. It got so bad that the opposite tire would leave the pavement, and this was at 35mph.
It also explains the nasty looking fab job, because alot of that gorilla weld is the bracing after the breakage after the wobble.... well you catch on..
I figured worse case scenario, there will be some odd tire wear over time, since the toe constantly changes with suspension flex, but as far as actual bumpsteer, haven't had any yet. I actually think the tires will wear very similar to the ford front ends.
fordtech said:
is that rack mounted directly to the axle?? <snip>
I wasnt taking in the axle shifting due to the trackbar. Im not sure it would move enoough to have a large effect, but if it does the effect would really cause weird changes in toe.
I tried real hard to convince myself that I could mount the rack directly to the axle. That would solve all the weirdness. However, in order to do so, I would have had to completely redesign a trackbar to give clearance for the rack, and give the truck enough lift to ensure the oil pan could not come in contact with the rack. I played with the idea for several weeks, but the final decision was no axle mounting, most especially for the amount of steering shaft telescoping that would be necessary.
As for the trackbar's effect on steering, YES, and I attribute almost all my weirdness in feeling to that. The weirdness is actually in body roll while hitting a bump. If I hit on one side, it feels normal, if I hit on the other, it feels as though it actually SHOVEs the body side to side. I'm sure the current geometry of things is to blame, and because I moved the upper mounting point for the trackbar down from the framerail to the rack cross member. It's weird, for sure.
-Steven
