What is the significance of scrub radius?
How some positive scrub radius provide good steering feedback , but on further increase in its value , cause steering failure?
I guess most people knows the term, but allow me to explain for those rare souls that have never thought about it, like the lead guitarist of Kazakhstan Symphonic Orchestra, people without email accounts or, perhaps, Alpha Centauri aliens (if you believe Greg... and you should).
It's the distance from the center of the contact patch to the point where the axis of the suspension should touch the floor(that axis is the imaginary line that joins both ball joints, the gadgets that hold the wheel in place and allow it to turn).
As you could deduce, when you turn the front wheels they do not turn right on the patch but on the axis of suspension, so the tire scrub the road, thus the name "scrub radius".
A positive radius means the axis "touches" the floor on the inside of the patch.
When you turn a tire with a positive scrub radius, the tire tends to roll, hence you can move it easily when the car is stationary.
When you brake, a large scrub radius changes the steering because the braking force acts through the patch and it creates a torque on the suspension axis which, as I tried to explain, do not coincide.
Hence a small scrub radius will make the car less sensitive to changes in steering when braking.
If you make the scrub radius large enough you induce large moments (torque) while braking that (maybe) could cause fatigue in the suspension elements but I've never heard of a suspension breaking because of it.
While you`re googling for scrub radius, following George Locock`s recommendation, please, would you be so kind as to google for me who will win the WDC, Hamilton or Rosberg?
