Front suspension design input needed

[358Mustang]

Originally Posted by Ron Sutton

Gotcha. You're going the conventional route.
Based on what you said, it looks like you're looking to travel the front end in the 3/4" to 1-1/2" range (at the crossmember). I should have asked this earlier ... will you be autocrossing, running track days at full size road courses or both?

Regardless, for a low travel/high roll suspension set up …
• If your priority is autocross or the low speed corners of road courses, your target RC should be around 1” in full dive.
• If your priority is the mid-speed corners of road courses, your target RC should be between 1.5” to 2.5” in full dive.
• Of course, you can set it for anything in-between.
• The higher the RC is within the range 1” to 2.5” favors the mid-range corners. Lower favors the low speed corners.
• If optimum lap times matter to you, the answer of what is the optimum roll center will come through testing.
• If you're not that hardcore & just want to have fun running the track hard & fast, pick what makes sense to you & go run it.

P.S. I concur with Mike's tips above. He & I both favor high travel/low roll set-ups, so that influences our designs & geometry settings, including lower roll centers ... and long control arms which tame the geometry changes. The farther you travel the front suspension ... the more the longer control arms help.

I attached an illustration of my Track-Star front suspension which we travel in the 4" to 4.5" range at the crossmember (more at the outer front wheel). I design these custom for each client's particular car, but the LCA's end up in the 23" to 25.5" range & UCA's in the 11.75" to 13" range. This allows us to travel the front end that 4-4.5" and have the optimum geometry throughout the travel.

If you're traveling the front end only a little, then control arm length is less of an issue.

Thanks a lot for the diagram of your suspension. That helps me a lot to visualize things... This is a strict road race car, that I am trying to build it to be as fast as possible (isn't that the point? )

Here is a picture of my car and what I have mocked up, which is basically an engine and the start of some frame work, so like I have said I more or less have a clean sheet. I wanted to go with high backspace wheels to keep the scrub radius down. I plan on using an 18" wheel, will obviously be custom due to the bolt pattern...