OK, Mike - been away for a couple of days and didn't see this thread and since Jim is the only one on here who remotely addressed your question, here goes (get ready for a long read, and I'll address Stan's remark as we go along):
First, SUSPENSION GEOMETRY: In a nut shell, swing arm wheels don't go straight up and down - they travel around an arc of about 18 inches. As they go up, the bottom of the wheel goes out. As they go down, the bottom of the whel goes in and begins to tuck under. Hold your arm straight out at your side, fingers pointed straight down. As you raise your arm, your finger tips will angle out - that's what your wheel does.
When you install a camber compensator you are putting a leaf spring across the bottom of the axles (or swing arms, if you prefer) which is meant to (a.) hold both wheels parallel to each other as much as possible and (b.) attempt to keep the rear wheels on the ground and NOT tuck under on hard corners. The harder you take a corner, the more likely a rear wheel will, with the movement of the body from a "flat" line, try to tuck under and THAT causes less and less of the tire tread to remain on the ground. It has no choice - that's the way the susension geometry works. If a wheel tucks under and loses a significant amount of tire tread ground patch (it actually pulls up to 75% of the tread patch up off the ground from the inside to the outside), then it is possible to have a catastrophic event occur where the car can actually flip over as it rolls onto the outside edge of the wheel - the same event that made a name for Ralph Nader on the early, swing axle Corvairs.
The camber compensator will alleviate some of the oversteer which causes the movement of the rear axles, but it can't correct it - remember, those wheels HAVE to move that way and all you can do is try to limit some of the movement which will push the catastrophic event farther out in the performance profile.
Now, with IRS, the wheel is rigidly held by a triangular assembly (diagonal arm and spring plate) which holds the hub and wheel in strict alignment as the wheel goes up and down. The wheel HAS to go straight up and down - that's the way the suspension geometry works with IRS. The important thing is that, as the wheel goes down, the bottom never tucks in. The geometry holds the wheel straight, and the tire patch is planted on the ground. There is also the issue of sidewall flex which is exascerbated with a swing arm suspension for the same reasons. Tuck a wheel under with a mushy sidewall on the tire and it just buries itself faster if the wheel itself is already angled onto the outside edge.
Now, to Stan's comment. If you never go out on a road track and never push your car to the limits, you'll never see any of this stuff. If you have to ask what it all means, you'll probably be too scared to try to make it corner that hard in the first place and will never notice the difference.
I built 6 dune buggies with swing arms before I built my first one with IRS. The handling difference (I autocrossed both styles) was SO MUCH better with IRS that I've never built a car with swing arms since.
Pearl has IRS, 3/4" (19mm) anti-sway arms front and rear, 16" X 7" wide rims all around with 205 tires front and 225 tires rear and sits pretty low. There are very few cars around the Savannah area that it won't out handle, including some nice 911's and more than a few Cobras. I'm way underpowered in those classes, but I CAN pull away from all of them in hard cornering with just a touch of understeer (more tire pressure should help). The next car will be set up just as well, BUT will have 300hp to the wheels, thanks to my son. THAT will be even more fun on the track!
Hope this helps. Need more info? email me!
gn
