Calculating spring/sway bar rates, roll center, etc

[RoadRacer]

I'm just starting the journey to calculate what I should be using for springs, sway, etc., using real math not the seat of my pants

I subscribed to Suspension Set-Up With the "Weight Transfer Worksheet (WTW)" and this weekend I will be starting the process of measuring suspension geometry, motion ratio, sprung and unsprung rate, etc to input into the calculator.

A couple of things are tricky to measure, so before I go any further I thought I'd ask first.

Has anyone calculated the Roll Center Height for the Hot Rod? I'll be using this Suspension Geometry Calculator, but I'd rather just use the number if someone (like FFR!) has it.

Also, I need to estimate (impractical to measure) the Height of Sprung Center Of Gravity. No idea where to start there, but this is their guidelines:

Height of the Sprung CofG: Make it the same as equivalent known cars. For Mazda MX5, we know it is about 450 to 475 mm. Production sedans, might be 500mm to 650 mm. Open wheeler and sports racing cars – we should really measure it. But measuring height of the centre of gravity is time consuming and difficult. We suggest to estimate a value around 300mm - 375mm.

[Just 1 More]

James, I love how deep you're digging in to this and patiently await your findings. Another site i'm on has a lot of very smart suspension gurus that might also have some info. Might be worth a shot. https://lateral-g.net/forums/

[J R Jones]

James,
Those geometric characteristics are more significant for motorcycles.
At this point the dimensions are academic. If you are designing the vehicle you can optimize these points. Since FFR prioritizes styling and an archaic vehicle, these dimensions are compromised compared to a race vehicle. We might assume the dimensions are optimized for this car. Changing the geometry on an existing structure would not be easy, and incremental changes would likely be hard to appreciate empirically.
Have you visualized what these geometric points are?
jim

[RoadRacer]

I finished all the measurements today after nearly 3 days of effort! Fascinating stuff. I found answers to my earlier questions.

Measured corner weights, COG (by jacking one end of car up), roll centers front and rear, unsprung weights front and rear, motion ratios for suspension and sway bars.. it’s been fun!! Lots of spreadsheets and online calculators.

I’ll post the results once I’ve been through it all..

[RoadRacer]

I decided to post all the process on my build thread ,so you can see it starting here: https://thefactoryfiveforum.com/show...l=1#post543236