View Single Post
Old 08-24-2006, 04:39 PM   #1
DustenT
doesn't care about you.
 
DustenT's Avatar
 
Join Date: Aug 2004
Location: Denver, CO
Posts: 3,925
iTrader: (0)
Default AutoCross Checklist (FAQ)

Let's create a thread for AutoCross n00bs.
Note: This thread is a collaborative effort, I can't possibly answer all of these on my own. Thank you to everyone that contributes.

Important Links:
SCCA Solo - http://www.scca.org/Solo
2006 Solo Rule book - http://www.scca.org/_FileLibrary/Fil...solo_rules.pdf
SCCA Solo categories - http://www.scca.com/_filelibrary/Fil...categories.pdf
Autocross.com - http://www.autocross.com/
AutoCross FAQ - http://www.sfrscca.org/solo2/faq/ (a bit outdated)
AutoCross Forum - http://www.autocrossforum.com/forums/
AutoCross Do's and Don'ts - http://www.sfrscca.org/solo2/faq/etiq.htm
what is allowed in stock and real world results on a dyno - http://www.grmotorsports.com/news/03...ompetition.php
tons more info can be found here http://www.moutons.org/sccasolo/

What is AutoCross?
http://en.wikipedia.org/wiki/Autocross

What do I need to bring to an AutoCross event?
-Helmet (most organizations will have one to borrow if you don't have one).
-Tools - I have extra brake fluid, and extra oil. As far as tools I take my oil cap wrench, a few different metric sockets and wrenches, 6-15mm. And my repair manuals. I've yet to have a problem where I needed to use any of it. Jack stands, and the stock BMW jack. I don't want to carry around my 3-ton hydraulic jack. Our local BMWCCA also recommends bring extra oil filter and extra spark plugs. Not sure why... I've not had a breakdown where I needed any of the tools.
http://www.sfrscca.org/solo2/faq/chek.htm

What should I check before my run?
All fuilds, especially oil.
Clean out all the way.
Suspension components.
Tire pressures about 40 psi. That way you can move them down as you see fit.
Chalk the tires.
Check under the car to make sure nothing is hanging down.
Make sure that you have had enough to eat and drink.
Possibly tuck in the mirrors and remove rearview mirror.
Have gloves if you want.
Both hands on steering wheel.
Make sure your enigne is warmed up.

What should I expect at the event?
I don't know about all SCCA Solo2 events, but the ones around me require all racers to also work the track. So you have to be there at 8:30 for registration. Racing starts at 10am and usually takes 4-5 hours. You have to be there the entire time. If you are not out on the track working your assigned area they do not let you run your runs. So you basically end up standing around for 6-8 hours and racing for 5 minutes. I know the BMWCCA auto-x has assigned corner workers and you only need to be there for your run groups. One major reason I really don't care to much for the SCCA solo2 events I have been to so far.

Lots of sunscreen, a hat, sunglasses, and comfortable clothing are needed in the Florida heat. My first time out there was a novice group that did the tech inspections seperate from everybody else and also went over basic rules and what is considered unacceptable behavior. Burnouts, donuts, racing through the parking lot or other forms of wreckless driving results in instant expulsion from the event. I saw two tricked out honda's get booted from the last event I was at for doing burnouts.

What kind of helmet should I buy?
As for helmets I'd buy an SA2005 rated helmet. This way you know it will be allowed for atleast 5-6 more years. SA2000 or SA05 is fire rated, and what most driving schools/track days will require. I've seen some auto-x events where they say DOT motorcycle helmets are OK. But I'd go with something intended for car racing.

I have an MA2000 helmet it will be good at my local events for 10 years. A car racing helmet is fine and good, but I didn't feel the need to spend way more money than I had to.

Why do people but chalk marks on their tires?
Chalking the wheels is so you can see if the wheel is rolling over onto the sidewall. If it is you need to run more tire pressure

Should I turn off my traction control for the run?
Traction control should be turned off. Otherwise if that outside tire starts to slip a little bit it is going to cut your throttle. If you are familiar with your car you can use that little bit of wheel spin to your advantage and come out of the corner a lot faster than you could if the TC cuts throttle.

How does adjusting tire pressure make me faster?
Tire pressure recommendations seems to be in the 35-40PSI range cold.

For Tires: As stated, start at 40 PSI or so all around and adjust as you feel fit (so far I like 40F/38R with my 225/50R16 Goodyear Eagle F1 GS-D3s). Lower front tire pressures to increase under-steer and lower rear tire pressures to increase over-steer as a general rule, this has to do with the slip angles of the tires. The lower the pressure in the rear tires, the higher the slip angle. This actually allows the rear tires to help turn a little bit causing over-steer. If I make a left turn, the softer the rear tires the more they will try to keep going straight, the same principle as a 4 wheel steering car just with a much smaller effect. This wasn't intuitive to me at first; I figured it would be the reverse as I figured a harder rear tire would be inclined to slide out, which isn't the case.

Slip Angle: The difference in angle between the straight line of the tires and the direction it is actually going, i.e. it is like you are standing straight, but twist at your legs to the left or right. The difference between where you eyes are looking and your feet are pointing is similar to the slip angle of a tire. It is the twist in the tread. Lower tire pressures allow a higher slip angle. (correct me if I am wrong anyone)

What class does a bone stock 318ti run in?

A bone stock ti competes in G stock.

What modifications are legal in the stock class?
As a rough guide, if your car has modifications beyond this list it is not eligible for Stock Category:
Anything available on the exact model and year of your car as standard or optional equipment, as installed on the factory assembly line (nothing available only dealer-installed is allowed), plus
Standard OEM identical replacement parts
Accessories, gauges, appearance, comfort, and convenience items (not replacement driver's seat, though) that basically don't help
Added roll bar or roll cage to spec (not required, though)
Driver harness (no cutting seats to install, though)
Trailer hitch and/or tow bar mountings
Any wheel of diameter and width identical to a stock or factory optional wheel, offset within +- 0.25 inch
Most street legal tires that will fit the mounted wheels and stock bodywork
Any shock absorber of the same type and mounting as original; no change to standard spring mountings is allowed; suspension geometry may not be altered; gas or hydraulic shocks are permitted
Any brake linings; pre-1992 cars may use solid/braided metal brake lines.
Any front anti-roll bar (no change to stock/optional rear anti-roll bar, if present)
Manufacturer specified ignition settings only
Any replacement air filter element (or removal of air filter element); no plumbing changes, however
Engine bored no more than .020"; no balancing or porting/polishing of head
Replacement of any part of the exhaust system past the catalytic converter (if quiet)
Any oil filter
Added clutch scattershield


What happens at tech check-in? What do they look at?

The few events that I went to they checked if the battery was in place and not moving around, checked if the wheel was tight when locked (when the car is off). he opened up the hood and then looked around a little to see the condition of everything and thats it as far as the engine goes. then he just did your normal walk around to see if everything is on tight and looked at the tires brefiely and said ok and gave me a sticker. It was real basic. I heard that at bmw events they do much more detailed checks but at scca events it is real quick and not indepth.

Post your suggestions/answers/questions!
__________________

'99 Dinan M3
DustenT is offline   Reply With Quote