Finding the roll center and engineering its dynamics

[Advancedynamix]

I don't feel exactly happy with that guys explanation of what happens with a McPherson suspension.
(The guy on Engineering Explained)

I'm going to look around a bit and see if I can find a better analysis.

We also have a strange rear axle situation, and I'm not sure if we have a flat tracking pair of rear wheels/tires, or if there is a certain amount of independent movement. The "K-frame" rear axle mount looks similar to later VW Beetle setups that were designed to keep the wheels straight up and down instead of "Pigeon Toeing"

Comments anyone?

The trailing beam on a Festiva is very independent. The geometry change of the rear wheels is dependant on toe and camber settings. With 0 toe and 0 camber the wheel will remain straight through its travel (not considering lateral beam flex, which is a good thing). With negative camber and 0 toe, the wheel will toe in with compression and out with extension of the suspension. This helps turn the car. I recommend negative camber on these cars.

[firebush357]

So where do yall do RallyCross Racing? It looks like a lot of fun and I would like to setup a car for it but the only track around me that I know of wants $200 a day to play on the track... That seems quite high but I think it is setup more towards professionals.

[Advancedynamix]

If I were setting a festiva up for rally, I would leave the ride height stock and use different shock valving and spring rates/bump stops to control body attitude. These cars are actually already set up pretty well, except the shock valving is way off the mark. These cars are exceptional off road, and the short wheelbase means you don't need tons of ground clearance. In fact, I'm willing to bet you could even lower the car a bit if you could fit decent rally tires in the fenders.
The key to success is to keep it simple. If you spend too much time and energy trying to change everything then your just spinning your wheels. I bet Chris Duplessis could take a stock chassis festiva with a dohc b6 or bp and be competitive in it. Spend less time working on the car and more time driving it and making it reliable. Just my .02

[Greywolf]

I don't feel exactly happy with that guys explanation of what happens with a McPherson suspension.
(The guy on Engineering Explained)

I'm going to look around a bit and see if I can find a better analysis.

We also have a strange rear axle situation, and I'm not sure if we have a flat tracking pair of rear wheels/tires, or if there is a certain amount of independent movement. The "K-frame" rear axle mount looks similar to later VW Beetle setups that were designed to keep the wheels straight up and down instead of "Pigeon Toeing"

Comments anyone?

[Sid_RallyX_82]

One of the Engineering Explained videos was on roll center and how to find it by using imaginary lines through the control arm pivots on Double Wishbone and another line between each side's point of intersection and for McPhearson Strut, following the line of the LCA and a line perpendicular to the steering access at its uppermost point and again a line between each side's point of intersection, but, being that I can't take a cross section of my car out of it and make adjustments, does anyone have any ideas on what I CAN do? I would just ask for the setting You guys use, but almost everyone here is lowering their Festi for track and I'm going to raise mine for rally. Thanks guys!