Again, over my skis, but getting details from Will, Kent and the CAD guy.
The CAD designed front end allowed us to align the suspension, shocks and arms to the stock layout and geometry for steering. The designer was able to create and model the suspension into the rear steer configuration, use the stock spindles and allowed for testing in the computer. It works in the computer according to the designer. In the desert, we will see. Will is cautiously optimistic. If it works, we will have a much easier way to do spares and keep the cost down. If it does not work in real life, we will have to look at the spindles, move the rack and potentially move the diff. Not ideal. Really hope this works. According to the designer, it will work.
Great thing about these theories is that they are easily tested. Do well at the World Championships... Simple proof.
The Rack and Pinion is from Weller...
A few thoughts on steering geometry:
(this will take a few paragraphs, so bear with me. I promise it will be worth it in the end
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Your CAD guy was smart in designing around the OEM components. This is how building a car in a timely fashion is achieved. If you mandated a completely different and opposite steering layout, what would he have used as input for spindle geometry? Without successful past experience remodeling front spindles for front steer applications, he would be spending countless hours, and probably days using approximate figures for non existing hypothetical spindles. It surely would have stagnated the forward momentum of the design progress at that point. Like I said earlier, the decision to front steer our Maverick added 2-3 weeks extra build time.
As an eager young fabricator in the late 80's preparing to build my first race truck, I dove head over heels into reading everything I could get my hands on about race car engineering and suspension dynamics. No internet back then boys and girls. I'm talking libraries and mail order books. Big, fat boring books. When build time came, I carried over everything I could from what works in a road racing environment, and religiously applied those fundamentals into the truck I was building. I took rear steer F-250 camper special I beams and spindles, and forced them into complying to the front steer conversion I was performing, and still maintain proper steering characteristics. Enter Ackermann steering.
Lay-mans alert:
So, Ackermann steering was discovered in the 17th century for the purpose of helping horse drawn carriages corner with less resistance, and therefore, less fatigue to the horse (I told you, it's nothing that hasn't been done before!). Ackermann steering, quite simply is the ability of the inside tire during a cornering maneuver to steer at a sharper angle than does the outside tire. This is desirable because it is following a tighter circle than the outside tire is, therefore must turn at a sharper angle to avoid the friction caused by tire "scrubbing".
Anyhow, I remember watching the truck I built as it was being pushed through contingency at its first big SCORE event. Just a few trucks ahead of him was another new class 8 "hi-tech" build that used the same I-beam/spindle combination that I did (copycat!), except when converting his spindles to front steer (by converting, I mean just switching assignments for each spindle, The driver side spindle is rotated 180 degrees and used on the passenger side of the vehicle, and vice-versa. Then, wala! Instant front steer), he left the steering knuckles in the stock location, essentially introducing the reverse effect of Ackermann into his steering geometry. Suffice it to say that while we were able to push our truck around the corner, they could not do the same. They had to start it up and drive it around the corner. Between their front tires scrubbing, and the rear tires squealing due running a solid rear axle (spool), the resistance to turning was ferocious.
Then, the next day while watching both trucks entering into Osbornes Wash, it all became crystal clear to me why I spent the time to do it right. As our trucks front tires grabbed hold, and as though on rails, guided the vehicle effortlessly around the corner, while when the other truck negotiated the same corner, the front end immediately "pushed" hard to the outside of the turn, slowing the truck down considerably while the rear tires shot rooster tails high into the air as they struggles to push the lazy front end through the corner.
Fast forward 25 years, and I'm watching RG negotiating a kink in an otherwise endless straight pole line road in Baja. Now, these last 3 paragraphs are not narcissistic-ally added in an effort to toot my own horn, but rather to share a very poignant revelation that occurred to me at that very moment, which was this:
Perhaps pure Ackermann steering geometry in today's race cars is not the best or smartest design criteria. What I saw was a truck pivoting around the outside front tire as it crisply changed direction at over 90MPH. I thought maybe that due to weight transfer, and the higher slip angles the outside tire sees over the inside tire during a high speed turn, just maybe modern race vehicles, because of their vastly increased average speeds would be better off with "anti-Ackermann" steering. The modern off road racer is light and fast, and rarely is seen at low speeds "plowing" through a turn. Conversely, they are usually observed powering through lower speed corners at opposite lock, hard on the gas.
So, to Ackermann, or not to Ackermann. That is the question I ask. How say you Todd and Haans?
It's certainly a hard point to argue against, because when you think about it, the outside tire has more influence during a high speed turn as it is more heavily weighted than the inside one. It will consequently will see higher slip angles, so could benefit from turning a bit sharper by design, than the inside tire.
So Dave, for the sake of your thread, and input to it, possibly phase 1 will benefit from true Ackermann, while phase 2 with its more wide open motor and resultant higher speeds, will not.