Why 1/12 use negative caster gain?

Is anyone know why 1/12 use negative caster gain?

Coz car need more steering in off power, this calling reactive caster.

macau-rc 發表於 2011-7-29 11:18

                               
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Coz car need more steering in off power, this calling reactive caster.

how does this theory work?  Thx Ching.

reduces caster at turn in and increases it at exit

nb576uk2004 發表於 2011-7-29 23:34

                               
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reduces caster at turn in and increases it at exit

I see thx.  Thou would that make turn in sharper and exit more push (under steer)?  And if so isn't that the opposite needed.  Sorry, I am not experienced with 1/12

As you turn the wheels during cornering the angle of the caster affects the angle of the camber. The more caster you run the more the outside wheels camber will be increased negatively as the wheels turn. Since this camber increases the more you turn the wheels, called dynamic caster instead of static caster.

I still confused about reactive caster.
Why need reduce caster when off throttle.
It seem when you go straight, The car had over camber, Then you turn in corner compress front spring, The total camber back to actually car needed
In this, open throttle will fiel "push out", off throttle will turn-in more, That is correct feel.
But camber gain is against about this.
Why need fighting system?

in turn
reactive caster                     camber gain
normal--------------------------------------------------------
    over camber                    under camber
compress spring-------------------------------------------
    reduce camber                 increase camber

like

let say, 2 caster 2 -ve camber,0 reactive caster, when cornering, outside wheel  will change to 3-4 -ve camber, result in reducing the contact patch area traction
Using a reactive caster can reduce the excess camber and control  the contact patch size .

nb576uk2004 發表於 2011-7-30 13:13

                               
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As you turn the wheels during cornering the angle of the caster affects the angle of the camber. The ...

I think I get it now.  Pls see if below understanding is correct!  Thx.
  
If without reactive caster, at turn in, total "effective" camber (caster + static camber) may be too great, and the car could turn in too sharp (may cause over steering and tail out).

With reactive caster, caster is reduced at turn in and thus "effective" camber is reduced, making smoother turn in; and then at corner exit, caster increases thus "effective" camber also increases, giving more on power steering and therefore tighter corner exit.  

nel3838 發表於 2011-8-4 23:22

                               
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I think I get it now.  Pls see if below understanding is correct!  Thx.
  
If without reactive c ...

Or put another way, reactive caster reduces "over cambering" of static caster at point of turn in, making the car has smoother turn in; which in theory should also be useful for power wide sweep turns so the car don't dig turns so easily.

seemed difficult to understand.. but can try the effect with + - camber setting.

it is almost like rocket science...