Suspension and Balance

kharmata wrote: obviously someone has thought of how the amount of body roll relates to the amount of camber on each wheel and how it changes the tires parallelness to the ground - not too mention adding or subtracting the amount of tire sway as a result of all the centrifugal forces as you whip around the corner...which varies the pressure of the rubber to the ground at any one point along the contact area...

Back on the first page Tristan was collecting data to help determine the best alignment for him, and the camber issue might have come up then. Getting any kind of negative camber out of the front is troublesome, so less roll does mean that's less of an issue.

I don't know if either of us considered the issue of pressure of the rubber to the ground changing along the contact patch during hard corning. Setting the camber correctly should minimize anything like that, don't you think?

You do make a good point.

I'm taking physics at university right now, and basically you start out learning rough approximations of the truth. Slowly you consider more factors and have to take them into account which helps your approximations get better. Then you learn that the laws you were using are actually wrong in many cases (but still good approximations in many other cases) and so you must learn theories which approach the problem a bit differently. I have approached learning suspension and handling in a similar way, looking at the basics (eg. what happens when the shock gets stiffer/softer, and why?) and slowly learning more and taking more things into consideration. I know I have a lot more to learn about, though at this point I'm not too sure what I'm not aware of.

Capt Fiero wrote:   I don't mean to shoot anyone in the foot here,

Owwwwwwwwww  don't burst our theoretical bubbles now.
It's all in good fun and learning of course.

You are right, of course, David, theory only goes so far. Anything specific is simply luck-of-the-draw, but with the amount of money in simulators these days... Hell, there's a $15000 engine simulator on the market which can tell you damn near EVERYTHING about any engine you plug in - real or hypothetical. There's significantly less guesswork than before. For example, I used Forza to find a similar car (Intake-Restricted Ferrari GTO) and then tweaked what was already available to see what would occur with my Fiero. I'm not saying in the real world -1.7 on the rear will be perfect, but it will be bloody close. This is besides the fact though, as suspension has always been a comprimise. What works well on Tsukuba will not work well on Mugello.

Yeah, without the struts to keep them in check, spring stiffness becomes pretty much irrelevent. Still damn fun out there though, despite Gretchin's misaligned feet.

Time to pony up for Koni (RHYME).

Oh, buddy, let me know next time you're doing a run, my iTouch has a program for acceleration, deceleration and lateral G's, and if it knows your weight (As close as you think it is as race time) and gearing, it'll also tell you your horsepower estimate based upon acceleration figures.

Yep, you can log it of course. GPS is probably better anyways, as it's a hard mount. With the iTouch, you need to tape it to the centre console.

Dawg wrote: That's easy, just modify the one you have now.  Take it off the car and grind the diameter down between the body mounts.  I can show you how if you'd like. We used to do this all the time in my racing days. DG Cheese wrote:   or alternatively find a smaller diameter rear bar somewhere.

I had considered doing something like that, but wasn't sure if the shape mattered (if it had to be more or less perfectly round), and if it did, I didn't know how I would accomplish that.

I should have several months before the PCA autoxes start back up so I have time to save up some money if I want adjustable shocks... though I'm kind of tempted to go to some of the slush series events UBCSCC puts on.

So I've been doing some reading (mostly reading the Fiero Racing List) on this topic and related things over the past few days and have a few more things to share.

First, specifically for autocross, make sure you're not making a change that'll put you into a class where you'll be horribly uncompetitive. Take a look at the SCCA solo rules for classing info. At the end of the day for the more serious autocross clubs, your best time is adjusted by a ratio so cars of different levels can be compared a bit better. Just as an example, my car can fit in either HS (H Stock) or if I make changes to it, FSP (F Street Prepared), and there's further levels too. On a 50 second run, if my car is in FSP rather than HS I basically suffer a 1.75 second penalty, and I don't think I could improve my car that much without spending a significant amount of money on mods. If you just want to have fun this doesn't matter and you can just compare raw times (like what PCA does), but I want to see if I can make me and my car a bit more competitive.

This means I need to lose a few of the changes I've made to my car, like the cut springs and polyurethane sway bar bushings and end links (you're also not allowed a rear sway bar). But after a bit of reading, that may not actually be a bad thing. Aside from having lost some potential negative camber from cutting the front springs, apparently it also puts the front suspension geometry into a range where much more toe changes occurs resulting in more bump steer and after driving my car with cut springs, I think I have felt this. So although my ride height increases, I should be able to reduce understeer slightly with more negative camber and that may actually give me a slightly better handling car.

Since I won't be allowed to spend a bunch of money on upgrading my suspension in the stock class (aside from a few things), I should be able to invest in some nicer tires which are the biggest single upgrade you can make to the handling anyway. If I get tires with a slightly smaller diameter (which I think are allowed), that will effectively lower the car back down to where it was before, too. Unfortunately, your options for reducing body roll in the stock class are extremely limited so I may be forced to use a larger front sway bar which could make understeer a bit worse, although it would mean I require less negative camber so it could also help me. I don't know.

I'm stuck in FSP until I can do something about my 16" rims though, and I still need to actually go to one of the UBC events to make sure I like it, otherwise none of this matters as much. I do want more seat time though.

Patrick wrote: ... if I was serious about autocross and wanted to be competitive, I wouldn't be driving a duke.

Yeah, I'm in a slightly unique situation since I've invested so much money into my car to make it a good daily driver, I'd lose a lot if I sold the car and got a Fiero with a V6, so I'm stuck working with what I have.

Patrick wrote: Having said that, I have no idea how Colby and I managed to stay competitive with the V6 Fieros (except for Brian of course) at the last autocross. When I watch the videos and see the GTs accelerate at the start and coming out of the corners, I'm not sure why Colby and I with our 4-bangers weren't blown out of the water.  Doesn't mean I didn't have fun though, it was a blast!

There was only really a single main straight where there was a significant difference, the rest was down to handling and how fast you could make it around the sweepers and rest of the course. Watch Brian's GT and you'll see he goes way faster around the rest of the course beyond the straight section than any of us, I bet a properly setup Duke powered Fiero could be able to do that with a good driver. This is why trying to make my Duke a bit more competitive doesn't seem that crazy to me. There are even courses with almost no straight sections and I feel those are where the gap can get really narrow between the 4 cyl and v6 Fieros.

Patrick wrote: There's no way I'd return my '84 to the "bush-buggy" look just to comply with the totally stock class in autocross. I hate the huge wheel gaps that all stock Fieros have, especially the 84's which were the worst of the lot. I don't want my Fieros looking, ummm... silly.

Don't worry about it then if you decide to go an event where that classing is used. Everyone can still compare times with each other and you can always pretend you're in HS when comparing final results (which is what I intend to do before I get the proper tires). The classing thing is a bit annoying in some cases, but whatever, it'll still be a lot of fun.