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I have to ask since I am about to start another project, what do you think of the square set-up you are running (335 front and rear)? I have had mixed information, some say it is great and you get to rotate the tires, others say a slightly smaller front (305 or 315) help the car turn better. Thoughts?
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I'm a far cry from a driving expert, my only track cred comes from 20 HPDE's over the last 8 years and 7 years of shifter kart racing. But it seemed to turn in just fine to me I didn't notice anything strange. Just from a physics point of view that doesn't make sense to me - you turn the front tires 10 degrees and which tire develops a higher thrust angle? A small tire or a large tire? besides, any large bore racing class eventually moves to the largest front wheels they can package, Trans Am, Grand Am, LeMans. Whether that means the same for a street based car is open to debate, but unless you are going for top speed or are horsepower limited, I can't imagine you would want less tire, especially on our front heavy cars. Again what do they run in LeMan spec Vipers and Vettes ? Or the CP guys in autox ?
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How did you model the frame dimensions and suspension design?
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In this day and age of CNC laser cut Autocad designed wiper motor brackets, I actually find it kind of refreshing that I am so old school. My first try was a glorified ladder frame, and my 2nd try was all designed on Grape which is a freeware modelling software. Once you play around in something like Grape it doesn't take long to kind of "learn" where the structure needs to go for stiffness, and you are package limited for so much of it. So on the 3rd try I already knew the critical dimensions - firewall to rearwall distance, inside rocker dimensions, dash bar height, wheelbase, etc. So from there I literally design it in my head with a few paper sketches and just make sure I have structure near my suspension pickup points (the suspension is modelled in WinGeo). Ater that the cage superstructure is just built like any car with the roof mocked up in place. Speaking of mockup, i guess thats part of it too - constant and never yielding mockup -seat in & out, engine block in & out , roof on and off. Also the front and rear bodymount/crush structures are added later, so that final "fit" can be done with normal fabrication.
I'll go more into the suspension design later.