FormulaRedline

Well after digging through the faq and searching, I didn't find anything conclusive about this. Is it possible to do a quick alignment change on our cars? I'm really starting to dial in my suspension for autocross (Koni's, saner bar, tire pressure) and tweaking the alignment slightly (already had it done in shop to my best guess) looks like the last step.

Now I'm coming form running Formula SAE, where when we want to make an alignment change right after a run we get the driver's input, get the wrenches, tape measurer, and electronic level out of the tool box, lift one end of the 450lb car on top of the tool box, make the change, and go right back out.

Obviously, our Formula car was built to be adjustable though. How hard is this to do with the S2000? Has anyone attempted a self alignment? If not, what is standing in the way? Are some changes easier than others?

Thanks

The Reverend

It's time consuming, but if you have all the equipment, you can do it from home. I borrowed Richard's electronic gauge for camber/caster measurements. That worked well. I then tried using his stringbox for toe and I have to admit I think this is not the right way to go about it. I'd recommend a toe-bar for setting toe. It'll save you a ton of time fidgetting with lining up the stringbox. If the car drives straight with the steering wheel straight, then the stringbox isn't necessary.

The Reverend

http://racerpartswholesale.com/long18.htm

FormulaRedline

Hmm, this was certainly a lot easier on the tiny race car I don't know a whole lot about aligning street cars, am I going to have to disassemble anything or just loosen and turn? If it's the latter, can I just make my adjustments based on thread turns from the initial known setup?

The Reverend

The stock adjusters for camber and caster are cam bolts, so you can't really use thread turns to base your adjustments on, but if you've got some intuition, you can get a feel for how much to turn things pretty quickly. They're pretty easy to access. For toe, you have to turn threaded parts. Everything can be done with wheels on the car, but you might need to use a jack to get under to the camber and caster cam bolts. At stock height, it should be easier though.

Unfortunately, you're going to find that each adjustment will affect all the other adjustments some. So if you change camber, your toe changes, etc. Do camber, then caster, then toe.

FormulaRedline

Ah, ok. That's why the shop had so much trouble doing it in the first place. I guess the car just wasn't built with these adjustments in mind. Thanks for the help

The Reverend

No, it was built with them in mind for sure! Keep in mind that at each wheel, the hub is supported by three points - the ball joint from each a arm and the tie rod from the front steering/rear toe link. Now, if you positioned those three points so the two ball joints were both equally spaced above/below the hub, in line with the hub and perpendicual with the ground; then put the toe attachment perfectly spaced out to the right - you would have a 0-caster, poorly designed suspension, but alignments would be very easy because adjustments would be independent of each other. But where the three attachment points are at more arbitrary points, you will always have interdependency of adjustments where a change in camber results in a change in toe, etc. etc.

That's why the car is able to have a dynamic alignment. As you turn the wheel one way, the change in toe causes a change in camber to help you turn the car (this is caster). Also, as the suspension loads and unloads, you get changes in alignment to help the car corner better. As a result, you probably have around 4 degrees of camber mid-turn, but closer to 1 when you're going straight. So you get solid handling, without all the tire wear of running all that camber all the time.

Despite the major hype surrounding the AP1's bumpsteer, these cars have a very well designed suspension. Also, keep in mind that even the bumpsteer geometry of the AP1 was put there deliberately, it just turned out that most drivers on this board decided they don't like it and it makes the car less predictable. But it was not an accident that the rear end was built in such a way that you would experience toe change as the suspension moves.

When engineers design a suspension like this, they are even taking into account the softness of the suspension bushings and the dynamic alignment changes that will result from them squishing.

Anyway, bottom line here is that these are not design flaws in any way.

FormulaRedline

No, no you misunderstood. I have no doubts the Honda engineers put a lot of effort into the suspension and succeeded. However, when we built our race car, one of the design parameters for the suspension was easy adjustments. Like REALLY easy adjustments. As I described above, "one person with a tool box in between laps" adjustments.

I was hoping the S2000 would be close to this, maybe just "one person with a tool box and a jack" adjustemnts, but not quite. I was not saying they didn't design the suspension well, I was saying they didn't design it to be adjusted as easily as I hoped

The Reverend

I'm confused about what you think is more difficult to adjust here than on any other car. I don't think you could make it any easier to adjust than it is unless it had no bodywork (like your Formula SAE car).

The interdependency of alignment adjustments was just as much an issue with your Formula SAE car, even if you didn't realize it at the time.

FormulaRedline

^That doesn't help.

What I'm really missing is the ability to adjust in a predictable (possibly measurable) way. If I change one thing and it screws up another, but I can't easily make it go back, then I'm stuck.

Maybe I'm missing something though, is this not really the case? Believe me, I'm not trying to argue it's hard, I'm hoping it isn't!

Let's do a real world scenario to try and answer my question: If I'm out autocrossing or at the track and I notice my tire is not being used evenly side to side (by feel, pyrometer, visually checking the tread, whatever), can I jack the car up and dial in a little more/less camber before the next lap?