First of all let me say I'm lucky to be seeing this screen and posting on here. My cookies have been cleared but it seems that I'm able to log in from only certain sections of A.F. Weird! I sent a letter to the webmaster about my plight but haven't heard back.
But to the topic:
I know what Caster & SAI are, the angles they establish relative to the ground and the vehicle. I've seen a trend over the last 20 years of perusing alignment specs in cars from many countries that the amount of SAI designed into cars has almost doubled, while caster remains dependent upon application(family sedan vs. sports coupe). In some cases, amount of caster have gone down while SAI has gone up.
If I were designing a car from ground up, I would design in as much SAI as possible and keep caster under 4 degrees positive. My reasoning is that high amounts of positive caster(6-10deg) becomes highly
negative caster when backing the car up a long ways. I would keep caster minimal bacause I want quick reaction when I
turned, but at the same time want the weight of the car - via SAI - to center those wheels as quickly as possible out of a turn. I know that there are scrub radius issues with SAI that need to be accommodated, but is my thinking right?
Also - and this is a question for which I have yet to receive a direct answer either way:
Which - Caster or SAI, plays the dominant role in straight-ahead stability and quickly returning the steering-wheels to center from a turn?
If this is not a simple question to answer, please feel free to explain the ramifications dictating the decision on how much of each goes into a platform at the design level.
Thanks, and - hope all of you can see this!
