Camber Equations

[Alpine123]

Are there equations that describe the wheel camber change for a double wishbone suspension (and other types of suspension design) as a function of upper and lower arm length and deflection angle? I have "The Automotive Chassis" book from J. Reimpell but it doesn't seem to have the equations that I'm looking for. TIA.

 

[GregLocock]

Not as such, so far as I know. If your wishbone axes are parallel to ground and vehicle centreline then I suppose you could work them out, using the same approach as 4 bar links. The FAQ for the suspension forum lists several suspension analysers that will work it out for you even if the axes are not square on, some are free.


Cheers

Greg Locock


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[Alpine123]

Thanks for your response. I want to try to develop my own suspension analyzer software (long term project) and so I was looking for some standard equations that describe camber, castor, toe, roll center etc.

 

[WolfHR]

Alpine123, in the case that Greg has brought up you could reduce the problem to 2D analysis in which case it would be rather simple matter to solve. As far as 3D analysis goes, it will get rather complex, and I've managed to make a model set up just about right, so that it required only few quadratic equations to be solved. But it is in no way a simple task- you'd have to get familiar with vector geometry, and in case you'd want kinematic and dynamic parameters, differential vector geometry as well. (the latter part is surprisingly easy, so to say- I've managed to do the model without having even laid my eyes upon textbook on the subject of any sort, or any kind of 'outside assistance')

Unfortunately, I hit a 'snag' with my model, and even more unfortunately got no help/response with it here, so it just (for the time being) faded from my interest. The thing is that I've encountered some discrepancies when cross-checking the results with commercial software and couldn't figure out how significant the extent of those discrepancies was.

If this is a non-commercial project you're working on, I'd probably be willing to lend you a hand on it. If it was commercial, I'd be less inclined to do so- but I'd still tell you that my 3D suspension model is in 'public domain' and point you in the direction where it was published.

 

[Alpine123]

Thanks for your feedback. Actually, my long term goal is to write a software program that I can sell. I browsed through some books on suspension design that I bought a few years ago and it looks like the book "Multi-Body Systems Approach to Vehicle Dynamics" has the technical information and equations that I'll need.

 

[GregLocock]

Wel as Wolf said, for real suspensions, no, there aren't any standard equations. I'd go further and say that if your analyser ignores the effect of compliances then it won't be much help to anyone.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?