THX723
You mentioned earlier that the front and rear ratio was the main factor in vdc. Other than tire diameter, do you know of any other data that its calculating?

 

For Traction Control ... the F-R velocity ratio is the primary factor commonly used. The secondary factor (if used) is F-R acceleration ratio ... it weighs in a lot less than the 1st derivative.

Stabliity Control is far more complex and has Yaw rate factored in.

 

i guess what i asked was, if someone ran 1:1 vs 1:1.027 then would would it really affect the traction control? it's not that much of a difference.

 

You bet!

For a typical Traction Control system, TC is engaged before acutal tire slippage occurs. By comparing speed (1st derivative) and acceleration (2nd derivative) of the wheels (Front-to-rear) and sometimes other factors ... the system anticipates an impending wheel spin and applies an appropriate combination of throttle cut, fuel cut, and/or ignition retard just milli-seconds before predicted traction break.

2.7% may not seem a lot ... but when dealing with the 2nd-derivatives (acceleration) ... (2.7%)^2 = 7.25% ... now a much more significant figure.

 

THX723 Clint

Thats excellent info. Very useful. Thanks again.