Autocross setup

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JimW

Autocross setup

Post by JimW »

I've got a '99 sport Miata with the Goodwin C Stock autocross package (Konis, RB Sway Bar, etc.) and could really use some suggestions on what settings might be good to start from.

Specifically, where should the shocks be set? I was told Rear: full soft, Front: full hard. Is that reasonable? Another guy with a '99 with Konis was at medium/medium - He was faster than I but was undoubtedly a better driver.

Also, I used the "near" link holes on the sway bar, not the farthest out. That was purely a guess.

Finally, any suggestions about tire pressure on Azenis 615s? In the class, my instructor chalked the tires and we ended up at 33 front, 30 rear. It was a 50 degree day, but I've never heard of anyone running Azenis that soft.

The car behaved OK in the class, but I have no reference to compare to.

Thanks
Jim W
GeorgeH
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Post by GeorgeH »

Full hard/full soft is a "safe" starting point, in that the car will understeer in transistions. However that seems like an extreme setup to me, and is probably slow in that it induces too much understeer. What works best for you can only be determined with practice, but I'd reccomend backing the fronts off full hard a bit (say, 3/4 full stiff) and then adding some to the rear (say, 1/4 full stiff) as a starting point. Then, as you get more experience start tweaking the car one end at a time so that you can get a feel for how the damping adjustment affects handling. Specifically watch slalom behavior.

Caveat: My experience is all with NA, but I don't think the NB is that much different in this regard. Brian certainly has NB experience and may be able to give you a more specific starting setup.

Not sure about 615 pressures, but 33/30 seems low. But, remember that tires loose grip at lower tarmac temperatures, and therefore don't need as much pressure as you do on hot days.
'94 Miata, BR Coldside Supercharged SM2 plaything
'04 RX-8 sport, daily driver plaything
JimW

2nd autocross

Post by JimW »

Ran the car again with the front and rear shocks about 20% off full hard and full soft. Didn't notice a heck of a lot of difference but car seems pretty neutral where it is now.

The tires were at 36/33, and I'm pretty sure they were about right. It was about 70 degrees.

One of the local instructors (and a really fast driver) did a loop. Took almost four seconds off my time (he would have taken a trophy home w/ that time) and said it behaved pretty well, so I guess I just need to learn to drive faster.

thanks
Jim
Treibenschnell
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Post by Treibenschnell »

You answer is in the last sentence of your last post...


More and more and more and more seat time will make you better. I am glad to hear you've found a good work-able setup.
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Brian
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Post by Brian »

You guys are hired! Seriously good advice here. As George suggested, the starting setup I gave you was the "safe" one. By starting full hard up front and full soft at back the balance is going to be neutral to understeer....(all other things being equal) and it will tolerate a good deal of trailing brake as well as getting on the trottle too early at the end of the turn without spinning on you. As you get better you can bring the settings more equal and the car will be both faster and more ready to rotate for you at the limit. Ultimately, as Treibenschnell suggested, the critical issue is seat time and experimenting with different settings as you get better. Sign up for every practice day you can in your area so that you can experiment with the settings without worrying about blowing your time.
Brian Goodwin
Good-Win Racing
www.good-win-racing.com
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