Tony Posted December 3, 2011 Report Share Posted December 3, 2011 Description: Viewed from the front of the vehicle, the Rolling Force Lever can be illustrated by a line drawn perpendicular from the steering axis to where the wheel centreline intersects the spindle/ hub centreline. What can change it: Any modification or condition that can alter the position of the steering axis, or where the centre of the wheel intersects the spindle/ hub, will cause the length of the Rolling Force Lever to change. Using a wheel with a larger negative off-set will cause the value to change towards positive. Wheels with a smaller negative off-set will change the value towards negative. Changes in camber will effect Rolling Force Lever by tilting the spindle/ hub. Damaged suspension components will also change the Rolling Force Lever. Vehicle characteristics it effects: As the Rolling Force Lever gets longer, it becomes easier for road forces to disturb and sometimes steer the wheels. Because of this, additional road shock can be transmitted to the steering wheel. If the Rolling Force Levers are unequal side-to-side, the vehicle may pull. Road force and rolling resistance will act on the longer lever and try to steer the vehical away from straight ahead. An under inflated tyre will cause more steering pull when the Rolling Force Lever is longer. Got all that Quote Link to comment Share on other sites More sharing options...
hms Posted December 3, 2011 Report Share Posted December 3, 2011 No! H Quote Link to comment Share on other sites More sharing options...
Freaky Roadster Posted December 4, 2011 Report Share Posted December 4, 2011 So use as close as poss to the correct off-set wheels and make sure nothings bent. Quote Link to comment Share on other sites More sharing options...
Tony Posted December 4, 2011 Author Report Share Posted December 4, 2011 Information is power. The RFL must not be confused with the Scrub Radius, which is in essence the tyres contact patch within the mechanical pivotal points. Off-sets or spacers are a nemesis but few know the reason why.... now you do. Quote Link to comment Share on other sites More sharing options...
Kozy Posted April 4, 2012 Report Share Posted April 4, 2012 The RFL must not be confused with the Scrub Radius, which is in essence the tyres contact patch within the mechanical pivotal points. Are they not inextricably linked though? As far as I know, the scrub radius is what gives you the effects you mention but is tricky to measure, RFL is certainly a far more convenient method of checking. What can change it: Changes in camber will effect Rolling Force Lever by tilting the spindle/ hub. But it will tilt the wheel too so RFL should remain unchanged? Quote Link to comment Share on other sites More sharing options...
Tony Posted April 4, 2012 Author Report Share Posted April 4, 2012 The change of SAI in the unsprung chassis will move the SR, or in other words a change of camber from the unsprung chassis. Quote Link to comment Share on other sites More sharing options...
GamithUK Posted April 4, 2012 Report Share Posted April 4, 2012 So the RFL is basically how much the wheel is pulling/pushing on the steering system? The longer the lever the more force is felt on the steering wheel for the same input at the wheel (say a flat tyre or pothole)? A bit like torque steer (where the engine power can deform the steering) but it's determined by how far the steering axis is away from the wheel axis. Or am I mis-reading/understanding that? ttfn Quote Link to comment Share on other sites More sharing options...
Kozy Posted April 5, 2012 Report Share Posted April 5, 2012 The change of SAI in the unsprung chassis will move the SR, or in other words a change of camber from the unsprung chassis. Scrub radius as I understand it, is the distance between the point described by the SAI's intersection with the ground and the centre of the contact patch in the lateral plane. If you change the SAI by 1° by moving the upper ball joint inwards towards the vehicle, would you not alter the angle of the wheel too, and therefore leave the SR unaffected? For the SAI to affect scrub radius, would it not need to be adjusted independently of the wheel angle, i.e changing the angle between the SAI and the hub plane on the spindle? Maybe I have my definition of SAI wrong which is confusing matters, it is the angle between of the line through the upper and lower ball joints and the centreline of the car is it not? Quote Link to comment Share on other sites More sharing options...
Tony Posted April 5, 2012 Author Report Share Posted April 5, 2012 Adjustable lower arm and EZ twin pinch bolts would work. Quote Link to comment Share on other sites More sharing options...
Kozy Posted April 5, 2012 Report Share Posted April 5, 2012 Yep, think you've got me there with the bolts. Was single mindedly considering double wishbone adjustment via top arm. Quote Link to comment Share on other sites More sharing options...
Tony Posted April 5, 2012 Author Report Share Posted April 5, 2012 In truth it should never be needed but it's good to know. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.