Trochu wrote:
I've been working on the front suspension now though, and have some questions I'm hoping somebody can help me out with.
What result am I looking for with the Ackermann Angle in wishbone. I understand the basic concept of Ackermann, but sometimes the results for wishbone spit out a percent and other times its an angle. Am I trying to achieve as high a percent as possible at static with an angle that approaches zero degrees at full turn?
Secondly, what do you guys generally consider a "stationary RC" height, a movement of 1", 2", 3"? I've played around with my upper pickup points and can't seem to get better than a RC height of 2.185" at static, 0.186" (as shown below) and around 4" with a 2" drop. Is movement of 3.5" considered too much?
Lastly, I know, needy hey, are the Upper/Lower chassis pick-up-points generally equidistance fore and aft of each other? So the front upper is +4.5"/rear upper is -4.5" and front lower +7.75"/rear lower-7.75"? If so, how does one introduce caster angle as the UBJ, hub center, and LBJ on my Mustang spidles all appear to pass through the same vertical plane? I'm thinking of using this as an upper A-arm, is it the offset that introduces caster?
Trochu, Nice build! Not sure I can give you answers to all your questions, but here's a couple of thoughts:
From the F1 "Help" or F2 "Info key" in Wishbone:
Quote:
When STEER is zero, ACKermann percentage (STATic) is shown. When STEER isn’t zero, i.e. some lock is applied, the ACTual and the THeoretical toe differences for perfect ‘rail-like’ tracking are shown instead.
Also, good discussion on preferred Ackermann set-up in Carrol Smith's
Engineer to Win.
On the RC movement: Looks like a lot of movement, keep playing with the location of the upper a-arm pivots. Try dropping the upper inner pivots to get about a 10 degree slope in the upper arms.
On the caster angle: Set up an initial caster angle (7 degrees?) through longitudinal placement of the upper pivots, then dial-in/tweak with the Speedway a-arm adjustment.
Hope this helps a little. Others might be able to give you some more concise direction.