Double wishbone suspension variables

Owned by Alisa Shirkalina
Last updated: Sept 05, 2022
3 min read

Variable

Image

Depends on

Suggested/found values

Optimal values

Variable

Image

Depends on

Suggested/found values

Optimal values

Top A-arm angle and length

 

length depends on how it’s mounted to chassis, travel needed

check grabcad msxv for general guideline

 

Bottom A-arm angle

 

 

check grabcad msxv for general guideline

 

Distance between A-arms at steering rod

 

travel

 

 

Angle between A-arms

Instant center distance and height, roll center height

 

(same source as roll centre height)

 

Instant center distance and height

 

Then we selected the horizontal distance between roll center and instantaneous center as 53.22”.The position of instantaneous center which is more near to infinity is best suitable for a stable suspension design (same source as roll center height)

 

Roll center height

 

 

-Generally for the stability of vehicle it is required that the height of roll center at front is around 10.12” and at rear is9.44” for a ground clearance of 12” front and 11” rear. This roll center positioning provides better transmission of forces acting on the vehicle along the roll axis which yields good stability of vehicle and increased effect of roll/yaw damping

-

DESIGN AND ANALYSIS OF SUSPENSION SYSTEM FOR AN ALL TERRAIN VEHICLE (ijser.org)

  • The vertical distance between the roll center and the center of gravity determines the amount of body roll you’ll experience. The greater the distance between your roll center and CG, the greater the body roll

  • In theory, if your CG and roll center intersect, you’d have no body roll at all. This is a bad idea for two important reasons:

    • Your tires wouldn’t be able to handle the load, which means loss of traction,

    • The car won’t communicate with you when it’s close to its limit, so you’d have a false perception of how much (or how little) traction you have.

  • Effects of high and low roll center

    • Lower:

      • Reduced responsiveness

      • More body roll

      • Increased load transfer

      • Better on long, flowy tracks with long corners

    • Higher:

      • Increased responsiveness

      • Less body roll

      • Better for high grip conditions to avoid traction rolling

      • Better for tight tracks

(https://low-offset.com/workshop/suspension-roll-center/ )

Angle of shock