Ideal Geometry

[pro-tour79]

From what I get from the question " ideal geometry" is specific settings, the sheet metal around the chassis does not matter, but what does matter is weight, weight bias, CG, wheel base and track width, roll axis, and all of this in turn affects the settings, and driver feel, and spring, and sway bar rates.
but some items can be answered with "as little as possible" such as roll center migration, bump steer.
It is important to keep all that in mind.

[ccracin]

Originally Posted by pro-tour79

From what I get from the question " ideal geometry" is specific settings, the sheet metal around the chassis does not matter, but what does matter is weight, weight bias, CG, wheel base and track width, roll axis, and all of this in turn affects the settings, and driver feel, and spring, and sway bar rates.
but some items can be answered with "as little as possible" such as roll center migration, bump steer.
It is important to keep all that in mind.

You bring up some very good points. This kind of information is what I was hoping for from this thread. I talk to people all the time at local shows and cruises. They talk about improving the handling of their cars but have no idea what it takes to do that. They don't even know what questions to ask. They only know what they see in ads and from marketing wizards. The "average Joe" has never heard the terms Matt, You, and myself are throwing around here. If someone is going to spend thousands of dollars to upgrade their car or truck (we can't forget the trucks ) they should actually get an upgrade rather than some pretty tubular control arms that don't do anything but be tubular. Don't anybody get upset that sells tubular control arms! They have a place, but I just thought an open discussion about these principals would help alot of people.

As I said after your first reply, the sheet metal doesn't matter other than for weight and balance. I would argue however that if you look at the hierarchy of what systems to resolve first, the mechanical geometry of the front end should be considered first. This is only my opinion, hence why I brought it up first.

You have to take one system at a time and evaluate it. When you have what you believe is a good solution then you evaluate it against the other systems. If changes have to be made, then repeat the process. This is why some of these parts cost what they do. Quality vendors take the time and spend the money to evaluate these systems so they can educate you as you move along. Others spend the money on marketing alone. Hopefully this discussion will help figure out which is which for yourself.

Track width in an "ideal world" would be much wider than is practical in street cars. That is why I said earlier 'ideal" within reason. Wheelbase comes into play in my mind when you start evaluating both ends of the vehicle with regard to weight bias, balance, and evaluating the roll axis along with the rear suspension system.

It has been my experience that evaluating each end of the vehicle independently and then working to balance the 2 gets you closer faster than jumping back and forth. Any thoughts?

Anyway, thanks for the continued input pro-tour79. This is getting good. I threw out enough of my opinions, so lets see if anyone jumps in to tell me what is wrong with the way I do things. If anyone agrees let us know and hopefully we'll get some more good info.

Later,

[chevyIIpost]

Originally Posted by ccracin

They talk about improving the handling of their cars but have no idea what it takes to do that. They don't even know what questions to ask. They only know what they see in ads and from marketing wizards. The "average Joe" has never heard the terms Matt, You, and myself are throwing around here. If someone is going to spend thousands of dollars to upgrade their car or truck (we can't forget the trucks ) they should actually get an upgrade rather than some pretty tubular control arms that don't do anything but be tubular. Don't anybody get upset that sells tubular control arms! They have a place, but I just thought an open discussion about these principals would help alot of people.

Chad, this is the exact road I have travel over the last 5 years. My original thoughts where for a S-10 pickup suspension but I didn't want a salvage yard car. I went to the school of "Hard knox$" with a Jim Meyer set up because I had no clue what questions to ask let alone what the correct answers might be. I read and learned some after this purchase and found that what I had welded in my car had bad bump steer, only a couple of degrees of caster, a bad camber curve, no anti dive to speak of, and poor ackerman, etc. Basicly a street rod suspension for 40 Ford. I am now finishing up another learning process on a c5/c6 set up that has great specs and should do the job very well. Now I know enough to get in trouble when on my own but I can at least ask good tough questions and sort through the posers and the real doers. It just cost me $$ and time to learn this. I would hope this thread could help others avoid this long painful process.

[Silver69Camaro]

Originally Posted by pro-tour79

From what I get from the question " ideal geometry" is specific settings, the sheet metal around the chassis does not matter....

I totally agree with you, but you have to take "marketability" in mind. I absolutely love our Musclecar chassis, where sheetmetal truely does not matter...it all gets cut out and suspension function takes top priority.

BUT...if we had a "bolt-on" front clip for first gens that required cutting, we couldn't sell it. There is a fine balance between packaging and suspension optimization that is probably the hardest part about my job. For instance, my first instinct was to make the Camaro front clip hub track width about 62" wide, quite a bit wider than stock, but I had to bring it down to 60.5" in order for most guys to find a wheel that would fit. This increased bumpsteer from .001" to .014", which thankfully isn't a big deal.