Here is an analysis of the “stock” Goblin Rear suspension, meant to be a baseline resource for anyone interested.
Setup:
Wheelbase – 97.25in
Track Width – 58.3in
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 - 2.5in (limited by spring bind)
Droop Travel - 1.5in (limited by spring preload)
Static:
Roll Center Height – 1.6in
Camber Gain in Bump – 0.21°/in
Rear Subframe Ground Clearance – 6.7in
Pro-Squat – 23.9% (Highly Undesirable in all scenarios)
Pro-Lift – (w/ 40% rear brake bias) – 16.2% (Highly Undesirable in all scenarios)
Toe:
Here we have toe out on bump and toe in on droop. This contributes to roll oversteer in the rear. 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:
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.
The main drawback of the strut suspension is it's poor camber gain characteristics. The roll camber here is quite low, even by strut standards. This may be a good drag setup, but not ideal for street or track use.
Roll Center Migration:
There is some debate over the importance of lateral roll center migration, but most agree vertical height stability is important. It looks like vertical height stability was not a consideration in the design of this suspension.
If there are any questions or other graphs of interest let me know and I’ll get them added.
Setup:
Wheelbase – 97.25in
Track Width – 58.3in
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 - 2.5in (limited by spring bind)
Droop Travel - 1.5in (limited by spring preload)
Static:
Roll Center Height – 1.6in
Camber Gain in Bump – 0.21°/in
Rear Subframe Ground Clearance – 6.7in
Pro-Squat – 23.9% (Highly Undesirable in all scenarios)
Pro-Lift – (w/ 40% rear brake bias) – 16.2% (Highly Undesirable in all scenarios)
Toe:
Here we have toe out on bump and toe in on droop. This contributes to roll oversteer in the rear. 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:
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.
The main drawback of the strut suspension is it's poor camber gain characteristics. The roll camber here is quite low, even by strut standards. This may be a good drag setup, but not ideal for street or track use.
Roll Center Migration:
There is some debate over the importance of lateral roll center migration, but most agree vertical height stability is important. It looks like vertical height stability was not a consideration in the design of this suspension.
If there are any questions or other graphs of interest let me know and I’ll get them added.
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