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RSX Suspension Modeling Results

29521 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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Finally got around to reading this... great work.

This has me wanting to remove my bump steer bracket at the next available opportunity.
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 was under the impression most McPherson strut system gained a little negative camber with compression, but just very little camber in comparison to other suspensions(ie: dbl wishbone, etc)...

Positive camber gain during compression would be horrible for handling, be it a street car or a race car. :dontknow:
Regarding the bump-in that occurs on the front suspension.... Ive been thinking about this for the past few hours.

At what point does the angle of the tie rod cause binding within the balljoint and limit/restrict movement during steering operation??

Also, does anyone have a good approximation of the stock tie rod angle? Or a picture of tie rods(from inside the engine bay) at the stock ride height?
Bump steer is kind of a confusing name, as it has nothing to do with actually "bumps" in the road... but the "bump" stroke of the suspension(ie: compression).

I generally refer to it as "toe steer", as it tends to have a more intuitive definition.
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