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SCCA Autocross setup thread

94885 Views 647 Replies 36 Participants Last post by  Des
I thought I'd start a thread specifically to discuss autocross setup for the Fiesta ST for next years Street class (probably G Street). This way we can share our learnings on wheels, tires, shocks, sway bars and alignment.
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So to start things off I thought I'd ask about tires. Assuming that there is enough room I'd like to go with something a little taller and wider but that may not align with the available tires on the market.
Why do you want 16" rather than 17" Rivals for the ST?

WRT the Toyos a friend has them on her BRZ but says that they tend to start chunking in as little as 18 runs.
What this leads me to think, is that with its lighter weight, slimmer width, the more nimble handling, and the nearly close hp per pound of the FiST compared to the FoST - perhaps the Fiesta ST (with a properly good driver) could have won both days at the nationals. Meaning it should do better than the FoST on the tight course due to its handling, and beat the Celica cause it has near FoST hp. Then be nearly equal with the FoST the next day on the longer course. Hope we can see this happen next year!
I plan on making a good run at it! I've finished 3rd twice (BS Miata in 1999 and BS Solstice in 2009) so I'm hoping I'll have at least a reasonable shot at it :).
At the EcoBoost challenge the Focus ST was usually setting fast time on a fairly tight course.
I've got to read the rules but I don't think our classification is going to translate to instant domination.
Having driven both I think the FiST has greater potential than the FoST but I can see how it can be course dependent. Were the cars running with TSC/ECS enabled or not? I think the FiST will be easier to drive with everything off than the FoST as wheel spin will be easier to control. I also think the narrower width is a big advantage but perhaps one that every driver might not take full advantage of.

With this thread on autocross preparation/setup we can hopefully maximize the car's potential.
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there is no 17" Rival that will not rub the fenders. The Toyos have been known to chunk in heavy cars but are great with lghtweight cars.
My friend said the Toyos were chunking on her RWD 2600 lb FRS so there's at least a possibility on our cars.

Do the 17" Rivals rub on the inside? Would 1/4" extra offset be enough to make a difference?
In autocross getting a car to rotate is as important than anything. That involves getting the front to grip with little understeer and having the rear loose and manegable. From what I've read, the Fiesta does that.

One thing for sure, I have competed against locals that are multiple national champions and others taht are consistently nationally competitive. I have kept a book on how I fare vs. them in PAX and raw times with the GTI. I will have quite a bit of confidence in whatever I see when competition starts.......
+1 on the rotation thing. That was the secret to running a large 4WD car in HS against the MINIs, if you could make it rotate you could run with them, if you couldn't you were in for a long day.

WRT comparing against competition I have two ProSolo national championships and two Nationals 3rd places in classes of 50+ so I think I should be a reasonable yardstick, especially since my local NWR Pax class is full of current and former National Champions. Unfortunately it will be February before our next event so you folks in sunnier climates will have a big head start.
I know this is not a setup question, but I wonder if anyone has tried to get 4 wheels/tires into the hatch (with the seats flipped down) so you could swap wheels at the track?
I've gotten four Solstice 295/30-18 tires in the hatch without a problem, indeed I can get three standing up in the trunk area. With the narrower Fiesta tires you should have no problems at all. However with street tires being the rule next year there might not be a need to do so unless you're driving cross-country to an event or something.
Generally you don't want to mix tires in autocross besides perhaps running different sizes front and rear. In the unlikely case that the FiST won't rotate you'd start with adjusting tire pressures and if that doesn't work you'd want to stiffen the rear shocks.

Haven't Hearn the name Taka Aono in a long time! I ran FSP against him in 2003 when I co-drove a TR-6. He was almost untouchable although I got within 0.1 of him at the Fontana NT that year. I really miss running against him, he was a great competitor and a great guy.
My name is Alan. It's been a while since I regularly travelled to SoCal (I'm from WA) but I had a great run from 2004 - 2006 finishing second in the challenge at the SB Pro in my Audi 90, winning it all in the same car at the Fontana Pro in 2005 and finishing second again in 2006, this time in a borrowed ES Miata. Since that time I've ran a yellow Solstice GXP but haven't traveled much since 2008 (though I did finish 3rd in BS at the 2009 Nationals(). Since them I've been a fair-weather autocrosser and the FiST is my choice to get back into the sport full-time.
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Still the taller ratio could improve top speed in 2nd....waiting to see how people's set up shake out anyway. So have time to make a less hypothetical decision.
Remember you have 17 more horsepower in 3rd vs 2nd. This has made me wonder if shorter tires might be better on fast courses.
Perhaps I should instead have indicated that you have more boost in 3rd instead. It would be interesting to compare 50-60 times in 2nd using the D2s vs 3rd using the Toyos. Sure you will loose time to shifting but on faster courses (I've driven half of one of our local sites in 3rd before in the Solstice) it might pan out. In addition on some Pro Solo courses I've barely hit 50 and once again the short tires could be the ticket.

BTW I am not advocating for running short tires all the time but a dual-prong approach with two sets of wheels and tires could be an interesting one if you're running near the top.
The answer may be course dependent. For example if a course has a long third-gear section and the rest of the course is slow enough to not need third with short tires then the short tires would be better if everything else was equal. Temperature is going to figure into the equation as well as the Toyos are supposedly better in the cold.
Alan, what did you eventually go with? (And hi! We raced together in NWR until a couple of years ago).

I love the idea of a 225 but not so much the 50 ... Limbo, we'll be watching to see how you do!
Hey Des! :)

I have not choosen a tire yet but if I go for the Z2 it’s likely to be the 225/45-16 or maybe even the 205/50-16 depending on how well the tires fit on the rims.

Don’t expect a lot from me right off the bat as I plan on making my changes slowly over the whole year. Hopefully by Nationals I’ll have it well set up :).
I ordered the 215/45/17 ZIIs last night. We'll get data on both combos that way.
Got the Fiesta to a 41.6. It didn't rotate at all until I bled the rear tires down to 30 on the last run. Just three runs.No wheelspin except at launch, and in general zero drama, which means there was a lot more time to be had.
This lack of rotation is what I expect from the car which makes me think it will require a crazy-ass driving style with violent inputs to encourage rotation if a rear bar is not installed. But so far I've not raced it, this is just based on 6000 miles of street driving.
Alan, hope we'll see you down in Crows, El Toro, San Diego, etc. And yes, we do expect a lot from you :)
I'll be at Crows for sure, SD or LA is less for sure if I can't find a co-driver as I have almost no vacation time.
Des, you're running a 225/45-17? Tire Rack says that's 25 inches in diameter, quite a bit taller than the stock 23.5. I was thinking either a 225/45-16 or a 215/40-17 both of which are slightly taller than stock but closer to 24". Also both tires are 2 lbs lighter than the 225/45-17 which should help too.
When looking at the Tire Rack page on the D2 I failed to note the 215/45-17 when I made my size list, oops. I’m looking not just at outside diameter but also total weight of the wheel/tire combination, the distribution of the weight within the tire/wheel (since mass on the outside of the rim is worse) and the sidewall height. I’m still not 100% sure I’ll go with 16’s, it depends on what I can find in lightweight wheels in both sizes. Either way I’m aiming at tires around 24” tall, I don’t think I want to go any taller than that if I can help it.
At this point I would lean to Team Dynamics...but if I stick with 17's I think it opens up some other options.
I understand that Team Dynamics are popular with Ford folks because of their support of the Focus but I can’t see how they make sense when their lightest wheel is over 16 lbs while the OZs are luck lighter. The only potential advantage I can see is that they come in a 45mm offset if for some reason you rub on the outside with 42s. Is there something I am missing here?
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