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AutoX Questions

2K views 33 replies 18 participants last post by  jjacob 
#1 ·
Ok first of all, im starting autoX feb 24/25, and im way excited, as you probably all have seen from other threads :p

i guess my questions are about AT
yes, im an auto. which is NOT the best thing for autoXing, actually it could really hurt me. especially when here experience doesnt matter, and ill be in the "hella modded" class haha
I guess a question is - Overdrive off, or 2nd? or even worry about that?

my guess is O/D off is the way to go for me so i can keep the RPMs higher. i think dropping to 2nd would be a bit TOO high to run since theres usually i decent sized straightaway at some point.

i feel bad cause im on my DD tires, but i cant afford a new set with lower tread ratings, so its a price i pay...

also, reannas gonna do it too :smile: :smile: (im so proud of my girly!)
shell be on her 18's haha, we have no other options for her. those will slow her down tremendously added with being AT, but i think for her (and i both i guess), the point is to have fun, not so much to win.

any tips or pointers are greatly appreciated from the more experienced people here, although ive never heard of many of you guys going out and doing this... which is surprising, cause imo our cars are kinda... lame in drags, when theres so much more potential for autoXing out of us.

anyways, tips, and info regarding O/D and gearing would be nice =) thanks!!!!!
(and well take pics for sure!)
 
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#2 ·
with the autox's i've done, even with the straightaway you didn't leave second. but you might be on a larger lot. run it in drive for the first lap, and note the last gear your car goes into during the course, and keep the shift to that gear as the maximum during the subsequent laps. oh, and definitely keep o/d off.
 
#3 ·
I would say that if you do not exceed 4500 rpm or so in second gear, then leave it in second gear. You will get better engine braking going into the corners and be more into the power curve of the engine when exiting the corner.

Go read this thread, it will have the answers you want. I, as well as others, posted here on what to do.

http://g20.net/forum/showthread.php?t=42792&highlight=autocross
 
#4 ·
Never let being an automatic slow you down.

But anyway...

I'd definately bleed your brakes before auto-xing.
Clean out the car of anything you don't need, the less weight the better.
Make sure everything is in good condition.

The biggest draw back isn't that you're an automatic, it'll be your tires.

But, play with the tire pressure a bit. As the tires heat up they'll expand, so don't over inflate or the tires go pop, but don't under-inflate otherwise you'll be rolling on your sidewalls, but do play around, have a higher PSI in the rear than the front should help oversteer a bit.
 
#5 ·
Yeah, I was in my Subaru when I last AutoXed, but I never got out of second gear. However, my tires sucked and that definitely pushed my ETs up.
 
#7 ·
Curious why the 4500 rpm recommendation with the SR20? I run in second with a manual and run to redline at times.
Your redline with the AT is what Ryan? gotta be 80 or so? I wouldn't use drive, leave it in second if you can. Drive will spend lots of time downshifting leaving a corner.
Mind the tires pressures like the other thread link suggested. Check the wheel torque before hand. Make sure your battery is not going to move. If you get there without a battery holddown, or one that doesn't pass they should flag you out. Strip everything that's not fastened down out of the car, I pull the spare, jack stuff, and virtually everything that's not part of the car. Floor mats can be a PITA! If they get underfoot you'll hate it.
IM me later, I gotta run to pop's for a bit.
 
#9 ·
im not sure what speed redline will put me at in second. ill try once O/D off in drive, see how that sets me. not sure what psi to put my tires at... not sure what theyre at now to be honest. theyre 195/60 on stock rims, any recommendations?


and no worries, all my tish will be outta the trunk and all. not just for weight reduction, but i dont need stuff flying everywhere haha
 
#10 ·
ZaRPGfreak said:
i always believed the G had tremendous understeer, so i keep a lower pressure in the rear and it helps even that out.
I agree, the understeer is ridiculous. I would love to know where the extra 600lbs comes from compared to a b14. The front suspension is different but that can't add anywhere near 100lbs. Its like they filled the car with lead before they put the body panels on.

and your Addco Rear Sway should, in theory help, but I have the maxima one on mine, and I still get it just going down a normal downhill road at around 45mph
 
#11 ·
EPSentra said:
Curious why the 4500 rpm recommendation with the SR20? I run in second with a manual and run to redline at times.
Your redline with the AT is what Ryan? gotta be 80 or so?
Loren, just an opinion that if he would have to exceed 4500 to 5000 rpm that going up a gear may help. However, I would agree with you that it is unlikely that he will need to take the transmission out of second gear. Being his first autocross, he may not be paying attention to the max engine rpm. Didn't want to see him break something.
 
#12 ·
watch for brake fade, overheating, tire damage, unsecured objects, fluid leaks etc.

basically make sure youre 100% mechanically sound. autox puts tremendous stress on the entire car, so make sure youre tip top shape. anything thats not literally BOLTED down should be removed.

also balance out your car, get that center of gravity low and in the middle of the axles. (if you can) lower your windows cause theyre heavy, slide open your sunroof cause its kind of to the front, lay your rear seats down and strip that trunk. ill add more if it comes to me(my buddy has been racing MR2's and Miatas for years)
 
#13 ·
ZaRPGfreak said:
i always believed the G had tremendous understeer, so i keep a lower pressure in the rear and it helps even that out.

Try it the other way around. Over inflate your rear tires. The car will be much more predictable and it works because by over inflating you are riding only on the center of the tread and you aren't running on your sidewalls.
 
#14 ·
I raced my G the first time around and its an auto...never used drive because the time for the auto to downshift was terrible so I would suggest just keeping it in 2nd unless the course is large but autox courses rarely are. Also, listen to the tire pressure ideas because that will help tremendously. I know race Estock with my miata and tires are usually the biggest and best upgrade you can have on your car. One other thing is that you will have to take every loose thing in your car out...floormats, papers, miscellaneous stuff like that because they dont want things flying around in the car as your driving. Also if there are people there that will do an instructor lap with you let them...they will give you great advice on what to do and how to race the course...and most of all just have fun man...I mean you dont win anything even if you do win :p
 
#15 ·
#16 ·
ChickenWing said:
lower your windows cause theyre heavy

Might want to keep your windows raised, they actually add some rigity to the Body.

Anyways, doing lots of mods that a experienced auto-x'r could maybe gain half a
second on should be your last priority.

Just make sure the mechanical is in the sweet spot, and have fun, try out diffrent
entry speeds with or without braking applied and so on.

Find your cars Nirvana.

Trying to remember too much just makes you unconcentrated. After a couple goes
around the track you'll find you have more and more time to think of what ifs then
the first round, when everything might be a little hectic and caotic in your mind.

Thats at least my perspective on it. :D
 
#18 ·
ZaRPGfreak said:
i always believed the G had tremendous understeer, so i keep a lower pressure in the rear and it helps even that out.
It does. I meant help oversteer, as in helping to oversteer, not helping combat oversteer. But I dunno, my lines of thinking goes along with phxg20.

Why do you think SUV's underinflate their tires? To get more grip. If the front is more grippy than the rear, and the rear tires are over inflated, meaning, so inflated it doesn't have the ideal contact patch, but actually less than, the rear will be less grippy than the front so it'll be easier to have it kick out.

But yeah, in the end man, just make sure the car is in running order and just have a blast out there. Just enjoy the runs, learn your car, learn "techniques", left foot braking, trail braking, etc, then get faster later.
 
#20 ·
CarloSR said:
Nah !!! Forget about everything, just have fun.
Even with all these good ideas, Carlos has it right.

Just go out and have fun, you'll learn as you go.

To the tire pressure comment, run them how you have them normally, then after a lap or so adjust them to your car's needs and your driving type, everyone has a different feel, each car is setup differently.

For your first time just relax, take it slow and then work your way into it. Heading hard into AutoX can have its downfalls.
 
#21 ·
IONO_Anything said:
It does. I meant help oversteer, as in helping to oversteer, not helping combat oversteer. But I dunno, my lines of thinking goes along with phxg20.

Why do you think SUV's underinflate their tires? To get more grip. If the front is more grippy than the rear, and the rear tires are over inflated, meaning, so inflated it doesn't have the ideal contact patch, but actually less than, the rear will be less grippy than the front so it'll be easier to have it kick out.

Take a look at some pressure/grip graphs and you'll see that grip drops off much quicker with under-inflation than over-inflation. You will gain grip with higher than normal pressures until you reach a point where the tyre isn't making proper contact with the ground. The comment below the pic about increasing before decreasing is in regard to getting the best grip for racing, not making the handling 'loose'.
 

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#23 ·
IONO_Anything said:
It does. I meant help oversteer, as in helping to oversteer, not helping combat oversteer. But I dunno, my lines of thinking goes along with phxg20.

Why do you think SUV's underinflate their tires? To get more grip. If the front is more grippy than the rear, and the rear tires are over inflated, meaning, so inflated it doesn't have the ideal contact patch, but actually less than, the rear will be less grippy than the front so it'll be easier to have it kick out.

But yeah, in the end man, just make sure the car is in running order and just have a blast out there. Just enjoy the runs, learn your car, learn "techniques", left foot braking, trail braking, etc, then get faster later.

markbuts3 said:
Take a look at some pressure/grip graphs and you'll see that grip drops off much quicker with under-inflation than over-inflation. You will gain grip with higher than normal pressures until you reach a point where the tyre isn't making proper contact with the ground. The comment below the pic about increasing before decreasing is in regard to getting the best grip for racing, not making the handling 'loose'.
True, that's why they tell you bump up the PSI so when you're driving you don't roll over onto the sidewalls.

But still there will be times when pulling 180 will be faster than trying to grip a turn, specifically really tight, hairpin-like turns. Sometimes it will be faster pulling a 180, and continuing on your way, instead of understeering trying to take a turn faster than possible. Which is why bumping up the air pressure in the rear past the ideal contact patch, making it less grippy would be benefitial. I'd just rather lose grip in the rear and skid along, than lose grip in the rear and have part of my sidewall skid along too.

Going back to PSI thing. Over inflated tires have wear usually only in the center, small contact patch (good to lose grip, smaller contact patch), under inflated tires have wear on the inner and outter edges, larger contact patch including the sides the tread. Okay pretty obvious right...

I'm still thinking that SUV's have the larger contact patch from being under inflated to help grip, but from that diagram, maybe not. But there's a balance too in my mind, if there aren't any hard enough turns to cause the sidewall to roll over, I still think with the larger contact patch you'd be able to grip more.

But in the end, higher PSI in the back = more prone to oversteer (if past the ideal point, because of the less grip)
 
#24 ·
"But there's a balance too in my mind, if there aren't any hard enough turns to cause the sidewall to roll over, I still think with the larger contact patch you'd be able to grip more."

I think that's where the key is to the over/under question. When normal driving and especially off-road stuff under may provide a better grip through contact. Soon as the tire rolls over in X'ing, that goes out the window.
When I started out with the Victaracers I was using 34/30(f/r) and had a terrible roll-over. Now I run 42 and 40 and the grip is tons better. This in a 195/55/14.

Oh, and every different tire and setup is going to have it's preferred pressure settings. I'm not suggesting to run what I run for pressure, and I'm still tuning pressures also. I may change them in a month or two, or tomorrow.
 
#26 ·
EPSentra said:
Ryan, like has been said, first off have fun.
The only thing I would be super worried about is mechanical things. Oil, PS Fluid, Maybe Some high temp brake fluid, but I wouldnt be too worried about that unless its gunna be super hot out.

JW, are you gunna be down in cali or up in Oregon? If its in OR it would be fun to swing down and watch and see if I can give you any pointers.
 
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