Setting up for Autox

Road race, Auto X, or the Drag Strip

Setting up for Autox

Postby SowndWave » Sun May 13, 2007 3:42 am

I've been in one autox school and one autox event here, and I'm finding my car hilariously tail-happy. Whiteline rear sway bar + 320 tires (burning them off) is my problem me thinks... My plan is to up it to 160 tires.. not quite R's yet but close enough???

With stickier tires, it should slide less even though it has the stiffer sway bar correct? Currently the reason I slide so much seems to be weight transfer, not power over.

Thoughts?
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Postby ___Scott___ » Sun May 13, 2007 4:10 pm

If you are going to switch to another tire anyway, do that first then re-evaluate. If the rear is still too loose, then you generally want to soften it up to get more bite. If the rear sway bar is adjustable, set it to a softer setting. If not, consider changing the D-bushings to a softer rubber (assuming you are running urethane D-bushings now.) You can also run a lower air pressure in the rear tires relative to the front to gain a little more bite in the rear.
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Postby SowndWave » Mon May 14, 2007 2:07 am

The sway can indeed be set lower. With new tires I'm hoping it solves this issue a bit, not that tail happy is a bad thing, but right now its slightly too much. Though I did get the hang of handling it towards the end of the day..

I think I'll also try the tire pressure trick next time... I really hope I get a rainy AutoX to try it on too :D
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Postby CodingParadox » Tue May 15, 2007 10:21 pm

What else have you done to the car? I have, AFAIK, the second fastest AutoX alltrac in the country (I'm assuming gtfour77's is faster, but we both get FTDs in our cars so who knows =)), so I can probably help somewhat. ;p
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Postby SowndWave » Wed May 16, 2007 4:53 am

Wow, good help is easy to find in this case! Okay here's my alteration list:

-HKS EVC @ 16PSI. (yes I know it drops to 13 by the end of the rpm range)
-Centerforce Dual friction clutch
-TOM'S Chromemoly Flywheel
-Shifter bushings (but no short shift linkage)
-BOV not that it matters for autox..
-HKS Air filter
-HKS F-CON V
-HKS cat back exhaust
-Super Pro poly bushings front and rear on all control arms and other suspension bushings.
-Whiteline Adjustable Rear sway bar, stock front bar, both with poly bushings.
-Racing beat miata adjustable rear sway bar end links
-Drilled rotors(Slotted coming hopefully SOMEDAY from 935's)
-Stock pads(Porterfield RS-4's waiting to for rotors to be installed)
-Stock hoses(SS hoses, again, coming SOMEDAY from 935's)
-Mario's Alu rear diff mount and pvc rear subframe bushings.
-OEM Torsen diff
-160 AA tires...205/50R15 (gotta get skills up before R's and bigger wheels I figure.)

And I think thats everything. If that helps you in any way determine how I should set shit up. Other than that general tips with handling these cars on autox courses. The one I'm running now is VERY tight, and its prettyt difficult to make the corners. Take a peek at my Youtube channel, It has an in car video of one of my runs with my retarded comments.. please pay no attention to them... :lol:

http://www.youtube.com/profile?user=SowndWave
There's also a few other videos of other people competing that day..

THANKS FOR THE HELP! APPRECIATE IT!
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Postby CodingParadox » Wed May 16, 2007 4:57 am

With very similar mods, I liked the feel of the car on the middle setting of the whiteline sway. What you really need are springs/shocks, it's going to help you tremendously. That and tires. Also, go get an alignment from a custom alignment shop. Have them give you as much rear camber as they can give you, 0.5 degrees more front camber than that, zero toe, and max caster. That'll help a bunch as well. Start there, get shocks, then get camber bushings, etc. Bit by bit...
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Postby SowndWave » Wed May 16, 2007 5:26 am

Zero toe? I heard like 1/2 degree toe out on front and toe in on rear was an idea? As for camber.. like -3 degrees rear -2.5 front? I have the sway set in the middle right now too... Do I need camber bolts for those adjustments or should the custom shop be able to do that with the oem bolts.. Probably get the camber bolts, right?

Any reccomendations on wheel/tire size? Wheel spacers are a no no?
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Postby CodingParadox » Wed May 16, 2007 5:30 am

Can't get those without camber bolts. I was only able to get 0.8 rear camber out of the stock setup. With rear camber bolts, got up to 1.5. Front can only go to 2 though, with the Tein SS camber blates. I have camber bolts for the front I want to put on too. I want to try for 3 front 1.5 rear. With 2 front 1.5 rear, the car's pushy as hell, even with the rear sway on max.
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Postby furpo » Mon May 21, 2007 7:11 am

What are your tyre pressures and temperatures doing?

I have noticecd that my worn stock rear strut tops are flexing under cornering causing camber loss. If this is happening to you this will not help with your oversteer.

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Postby SowndWave » Mon May 28, 2007 2:20 am

Tried some stickier tires and things went really well, was even able to drop rear pressures by about 3psi compared to front. I think I'll be picking up some RT-615's soon to tear up.

Another thing I notice, the left front tire always seems to have slightly more wear than the rest with consistent pressures on the course today. It did have more work to do (many right turns), but what I'm curious of is if that corner is heavier due to the transmission weight on that side of the car wearing it a tiny bit more??? Or am I just acting quite the foooool....
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Postby stealthgtfour » Wed May 30, 2007 4:25 pm

ive got a 165 that i auto-x and ive got a question while were on the subject i cant seem to find any springs that are stiff enough to suit me.
and i would like to find some coil overs so i can corner weight the car.
also im a cheap bastard and impatient too so if i can make some thing and dont have to wait a month and a half to get what i need i will.

check out my in car and some pics http://www.myspace.com/turbosbymarske
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95 miata autoxer
88 165 evo killer(not 33mpg)

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Postby furpo » Fri Jun 01, 2007 8:20 pm

SowndWave wrote:Tried some stickier tires and things went really well, was even able to drop rear pressures by about 3psi compared to front. I think I'll be picking up some RT-615's soon to tear up.

Another thing I notice, the left front tire always seems to have slightly more wear than the rest with consistent pressures on the course today. It did have more work to do (many right turns), but what I'm curious of is if that corner is heavier due to the transmission weight on that side of the car wearing it a tiny bit more??? Or am I just acting quite the foooool....


You probably need to corner weight your car.

Roger
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Postby SowndWave » Mon Jun 11, 2007 5:34 am

...Back to a real thread...

Got a full weekend of use on the brand new RT-615's, absolutely a great step up, finally got pressures in a good zone, figured out how much grip they do/do not have, etc. What I wonder now is how camber will affect handling.

From what I'm hearing way of the subaru guys if 3degrees neg on the front and the rears is only .25-1.0 degree camber in the rear to actually allow them to oversteer a bit. With my whiteline rear sway, the rear end slides around the smallest bit which I would think to be optimum... But what do you think?

3neg front 1neg rear sound like a good starting point?
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Postby lumbercis » Mon Jun 11, 2007 7:07 am

^Have you read whiteline's handling article? I believe it is on their site and also somewhere in one of the sticky's in the suspension section. Anyway, they recommended something like -2neg on the front, but auto-x usually calls for more neg camber than road race, so -3 should be fine. IIRC, they had -1 rear camber also with something like 1 degree toe-out on the rears. Hopefully one of our hardcore auto-xer's will chime in with their setups. Maybe just keep the -3/-1 you have and add the rear toe-out and see how it goes.

@stealthgtfour: look into Ground Control. I believe they make custom coilover setups with pretty much any spring rate you want. I believe you can also order TEINs with custom valving and spring rates.

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Postby ___Scott___ » Mon Jun 11, 2007 6:14 pm

Here is some good reading from a BMW tuning shop regarding alignment: http://www.bimmerhaus.com/tech/align.html

There is a lot of BMW specific stuff, but a lot of good general info too.

For some good shock tuning info, check out this page too: http://www.bimmerhaus.com/tech/shocktuningTN.html
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