Jesse214
03-21-2012, 07:58 PM
Hi all,
I'm basically just trying to get my facts straight about should be a simple matter...
Reading through many, many sources (including Chassis Engineering, Race Car Vehicle Dynamics by Milliken & Milliken, etc.), there is no clear mention about caster angle affecting the measurement of scrub radius. Perhaps this is assumed?
From the reading, it's discussed that the scrub radius is determined by the KPI and spindle length. It's not until after scrub radius has been determined that caster angle is even discussed. Why??
I know for a fact that if you add positive caster angle along with postive KPI, your KPI/steering-axis line will be moved both further forward (caster trail) AND outwards. In other works, when looking at it in the front-view, the steering-axis line will intersect the ground-plane closer and closer to the tire center-line as you add more caster. With more CASTER, you will have LESS scrub radius (assuming you're beginning with a positive scrub radius). Am I wrong about this?
I've got this modeled in 3D so I can see exactly what the affects of changing caster/kpi are. It's just not clearly discussed in any material I've come across.
Any thoughts on this? Should I be IGNORING caster angle until the KPI and scrub radius are decided?
I'm basically just trying to get my facts straight about should be a simple matter...
Reading through many, many sources (including Chassis Engineering, Race Car Vehicle Dynamics by Milliken & Milliken, etc.), there is no clear mention about caster angle affecting the measurement of scrub radius. Perhaps this is assumed?
From the reading, it's discussed that the scrub radius is determined by the KPI and spindle length. It's not until after scrub radius has been determined that caster angle is even discussed. Why??
I know for a fact that if you add positive caster angle along with postive KPI, your KPI/steering-axis line will be moved both further forward (caster trail) AND outwards. In other works, when looking at it in the front-view, the steering-axis line will intersect the ground-plane closer and closer to the tire center-line as you add more caster. With more CASTER, you will have LESS scrub radius (assuming you're beginning with a positive scrub radius). Am I wrong about this?
I've got this modeled in 3D so I can see exactly what the affects of changing caster/kpi are. It's just not clearly discussed in any material I've come across.
Any thoughts on this? Should I be IGNORING caster angle until the KPI and scrub radius are decided?