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RSX Suspension Modeling Results

29519 Views 106 Replies 40 Participants Last post by  XDC5SX
I recently took a vehicle dynamics class. We needed to do a class project, so I (and two additional group members) chose to model the RSX suspension. I am attaching the final report so that everyone here can benefit from it. Note, I am posting this here in the autocross forum rather than the suspension forum because it is more relevant to those of us who track our cars or do autocross.

Basically, the car's suspension was measured so that the location of every suspension point was known in x, y, and z coordinates. Next, the suspension was modeled in Solidworks. From this point, lots of info can be measured/calculated.

Anywho, we looked at camber gain, both from suspension compression and from steering input. We also did roll center heights and bump steer. All of these were done for the front and rear. Additionally, aftermarket modifications were 'made' to the model and their effects on the above parameters analyzed. The modifications made were roll center adjusting ball joints, caster/camber plates that move the strut top inward 3/4" and rearward 3/4", raising the inner tie rod ends 1.25", and lowering the inboard side of the rear top link of the rear suspension 3/4".

DISCLAIMER: Every attempt was made to be as accurate as possible during this project. However, it is exceedingly difficult to measure the suspension perfectly. As such, I do not guarantee any values as being 100% exact. They should be pretty darn good though.


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Your recommendation to maximize camber using bolts rather than plates is interesting. I theorized the same thing and had the shop max my Ingalls bolts out before touching the plates. In addition, it minimizes the toe impact since you're moving the strut, and therefore the steering arm, less.
I'm curious though... everything I've read about this chassis for the last 9 years, as well as generally understood behavior of macstrut suspensions, suggests camber loss with compression. Unless I'm reading this wrong, you're suggesting the RSX gains negative camber w/ compression? That's an entirely new assertion. It makes me weary of the model.

I'm not challenging your intent or qualifications, but as a software engineer I know everything, especially the first time around, has at least a few bugs ;)
I definitely agree it's horrible, but I always understood that that was what happened, and a primary reason for maximizing static neg camber in our cars. If I'm wrong then great :)
Wow... looks like RSD + steering bracket will be overcompensating unless you're seriously slammed.
I'm not sure because I only modeled the one situation. If I had to guess though, I would say that if you moved the strut only in caster and not in camber/kingpin, it would not affect toe much. However, if you were to increase camber/kingpin and not caster, it would have more of an effect. This is because the greater angle (kingpin) the strut is at, the more the attachment point for the outer tie rod moves inward with suspension compression, thus creating more toe in.
Yeah, surely changes to the caster angle impact toe, but not nearly as much due to the plane.
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