"Stock" Front Suspension Geometry

Sebnuts

Well-Known Member
Here is an analysis of the “stock” Goblin Front suspension, meant to be a baseline resource for anyone interested.

Setup:
Wheelbase – 97.25in
Track Width – 59.4in
CG Height – 20.5in
Frame Rake – 1°, Nose down
Tires – Stock LNF SS 225/40R18
Wheels – Stock LNF SS 18inx7.5in, 42mm offset
Bump Travel - 0.9in (limited by upper ball joint bind)
Droop Travel - 1.2in (limited by shock stroke)

Static:
Roll Center Height – 3.8in
Camber Gain in Bump – 1°/in
KPI – 6.7°
Castor – 7.0°
Trail – 1.5in
Scrub radius 0.72in
Front Frame Ground Clearance – 4.6in
Anti-Dive – 4.4% (w/ 60% front brake bias)

Toe:
38038

Here we have toe out on bump and toe in on droop. This contributes to roll understeer in the front. There are many factors that contribute to the overall balance of the car, and this is just one of them.
Understeer and oversteer are not necessarily good or bad. Some highly skilled drivers may prefer oversteer, because of their ability to adjust and react quickly. Most production cars are setup with understeer, because most drivers are not skilled enough to take advantage of oversteer characteristics.

Camber:
38039

In general, as this curve approaches horizontal, grip in a corner will go up and grip in a straight line while accelerating or decelerating will go down.
This particular curve is more aggressive than you would want for a street car and is more suited for the track.

Roll Center Migration:
38040

There is some debate over the importance of lateral roll center migration, but most agree vertical height stability is important to the overall stability of the car in a corner.

If there are any questions or other graphs of interest let me know and I’ll get them added.
 
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