Suspension Modeling

[bobsiopener]

Hi,
I've been trying to model the front suspension so to speak. I've taken a several measurements that I've listed below. I did this so that i could plot out the camber curve through the suspension travel and to also see what a set of drop spindles would do to the Roll center and the Camber curve. Listed below is the stock measurements, it's intresting to note that the roll center drops below ground when the suspension is moved just one inch so if you've lowered your car the RC is below ground. If anyone has any suggestions on how to post the plots for camber and roll center let me know

Upper A Arm chassis mount height 16.25
Upper A Arm spindle Mount height 15.75
Upper A arm length 9
Horizontal Chassis mount Difference (2.8 on chassis 0.6 on spindle) 3.4
Lower A Arm chassis mount height(stock 7.5) 7.5
Lower A Arm spindle mount height 6.75
Lower A Arm Length 12.5
Spindle Height 9
Front Track, center of Contact Patch 54
Distance from Contact Patch to Spindle 2

Calculations:
Horizontal Component Upper A arm 8.98
Horizontal Component Lower A arm 12.47
Angle of Top A arm -3.18
Angle of Bottom A arm -3.44
Static Camber -0.58
Roll Center height 1.72

[Grant]

Are you using a software package or modeling on a scale....model. Spindle height is for the stock spindle? My 16" dropped spindl;es is 1 and 1/16th inches longer...maybe you could plug that in?

Bumpsteer?

[bobsiopener]

Hi Grant,
I'm just doing trig calculations to find these things out, I don't have any software. with your dropped spindles and at stock ride height of 7.5 inches your Roll Center is 5.71 inches above ground.
thanks,
Bob

[Grant]

LOL...too bad my car is slammed to the ground. I think my RC is still below ground but I'm not smart enough to figure out by how much! Thanks a lot though, looks like they do make a pretty big difference if everything you calculated is correct in the real world.

[bobsiopener]

Hi Grant,
If you give me the ride height or the height of the middle of the pivot point (center of torsion bar) of the lower control arm then i can tell you exactly where your Roll Center is.
I can also post my calculations if you are intrested
thanks,
Bob

[AR4me]

Please do post the calculations and save the rest of us some time if we want to crunch the numbers on our setups.
Thanks,
Jes

[Grant]

I'm going to have to get back to you on that one. I have the wrong rear springs at the moment..my car is higher than normal. I will let you know in a couple of weeks!