Roll stiffness affecting Steering Effort .

satya430

I am currently working for a Touring Car Team . I have modified the front suspension geometry . Made the roll moment lesser and increased the Roll stiffness . Driver complained that the steering effort has increased considerably in the corners .

1.How does increased roll stiffness increase steering effort ? Does it have anything to do with the lateral load due to diff geometries pushing the tire down or giving it a more of a tire wall deformation effect ?

2.What are the methods to reduce steering effort other than
a.Reducing the scrub radius .
b.Increasing the knuckle moment (very difficult as it changes the steering geometry) .
c. Simply giving him a bigger steering wheel .

Ranger Mike

what exactly did you do? what is the car doing at turn entry, middle and turn exit?

satya430

I am working to change the stock suspension of a touring car (Mc Pherson Strut)
The front suspension geometry is being changed (the question above is about the new front geometry) . I have brought the front roll center of the car closer to the front Center of Mass(or mass centroid as referred to as in many books) . This has decreased the effective roll moment and thus increased my roll stiffness of the front without having to stiffen my springs .
Now as I have kept the new control arm ball joint in the same position of the old one , the KPI and scrub radius shouldn't have changed . As the driver complains that steering needs more effort now , what could have caused it .
The car trail brakes at the entry (dive-wt transfer to the front and roll-wt transfer to the outer ) . It kisses the apex (ideal condition) and then accelerates out of the corner . Pl. tell me if I am wrong .

Ranger Mike

i sure dfo believe the driver now has a handful driving..when you rasie the roll center it shortens the lever arm and you have a lot less weight being planted on the front tire in a turn. Plus you increase camber build
i am not a big fan of high RC..the lower, the better