Quote:
Originally Posted by funcars
There are books that have formulas for calculating sway bar rates based on diameter and shape. Then you can calculate wheel rate based on the combination of the springs, locations, angles and sway bar rates. You can start with wheel rates that have an equal percentage of rate front to rear of what you had before you started changing things and go from there. Some of the Steve Smith books have lots of explanation and formulas to help. They are older books but so are most of the cars we are messing with.
An interesting approach to get a good starting point for your combined wheel rate (vs throwing a dart) is to look at the moment-moment method as explained by the articles at circle track. It is based on using combined wheel rates and calculating the overturning moments at front and rear and attempting to get them approximately equal to get a neutral handling starting point. It is a slightly different approach than looking at roll couple lines and easier to calculate - take a look if you are interested.
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You are correct. But... When you are talking about formulas, calculations, wheel rates, locations, angles, diameter and SHAPE, moment-moment, overturning moments, roll couple, and the other settings they all translate into numbers.
Numbers some guys might not be able to get, or do and just really dont need that type of detail. There are some numbers through measurements that some guys just cant get, meaning they would have to do some major fact checking to get the raw numbers. More work than its worth.
I have read all the books. And feel like I have a grasp on the relationship between the numbers (measurements). But to understand it doesnt translate into how to pull the numbers out of the geometry of the suspension.
And some folks will get a kinda glazed over look in their eyes when you start talking about ALL the variables.
What I have found is the dart thrown into the board will get you very close if its just a nice street car or even a track car. And unless you are putting in a completely custom bar the extra number gathering is extra.
Weight of the car with a rough estimate and mimicking other cars that are similar.
I dont think there are many engineers looking at this thread. More likely a guy like myself that just wants to get a bar rate as close to usable as possible.
Many car guys that arent hard core racers are on this site. They just want a bar that is well within the range for their car.
Yes, there are some that want to dial it in as close as possible. But Im thinking thats 1%. The other 99% just want to get it pretty darn close..
But great info!!! JR