NC autoX suspension specs?

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NC autoX suspension specs?

Postby tbdomenz » Thu Jul 01, 2010 2:26 pm

Brian
My 2006 has the tokico adj shocks, eibach sways, rear sway in firm position, pro springs, 17x9 enkies with the Falken Azena 235/40 rubber. I normally run the shocks 4<>5 turns open. For autoX I go to 1/4<>1. I'm thinkin to add a little toe out for more responsive turn in. Looking for best settings for daily driver and also best settings for autox. I need to go for another alignment since I did all the suspension mods. I'm willing to compromise some daily driver +'s for better autoX performance. What would recommend?
Thanks
Tom
Tom in 60193
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Re: NC autoX suspension specs?

Postby Brian » Thu Jul 01, 2010 2:55 pm

Yes, try a little toe out (1/16th per side) front....and zero toe the rear. As for camber, depends on how much you are willing to compromise tire life. If not worried about it...go negative 2.5. Note that everything is a tradeoff and this does compromise brake performance a little...and if you have long freeway drives you can expect some annoying tramline.
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Re: NC autoX suspension specs?

Postby slartibartfast » Thu Jul 01, 2010 3:12 pm

It's the rare NC that can get 2° negative camber. What was Mazda thinking?!
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Re: NC autoX suspension specs?

Postby Brian » Thu Jul 01, 2010 3:28 pm

I happen to know this customer has aftermarket suspension....so he may get 2.0 negative or near to it. Perhaps Mazda was thinking that racing folks would do as they always have with the miata and add lowering suspensions...which then enable lots more negative camber. It all works out okay...
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Re: NC autoX suspension specs?

Postby tbdomenz » Fri Jul 02, 2010 10:20 am

Should have included this previously, Alignment was done with stock wheels tires 205/45/17...........
Front L - R
Toein .01 .02
Camber .08 .10 (maybe now it's -1-2 ? )
Caster 7.6 8.0

Rear L - R
Toein .01 .01
Camber 2.5 1.9 (maybe now it's -3 ? )

Since suspension mods and resulting lowering of approx 1.25", camber is more pronounced.
I see the tires now don't normally touch on the outer 1" of tread.
However, AutoX'g with 40psi uses the tread all the way to the outer edge.
Need to go back to the alignment shop.
What specs should I employ to get max AutoX performance?
More toeout is needed as you point out. What about caster camber?
Thanks
Tom
Tom in 60193
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Re: NC autoX suspension specs?

Postby tbdomenz » Sun Jul 04, 2010 9:49 am

Brian,
You indicate 1/16 toe out per tire. If measured in degrees we are talking about a wheel angle whose
Sine would be 1/8" divided by the wheel diameter approx 24-1/2", yes? The Sine is therefore .005102, which is approx 0°-18', or 18'/60' = .3 degrees
I just want to confirm my thinking to make sure me and the wheel alignment guy are on the same page. BTW, do you know what one turn of the tie rod end equates to in toe measurement? I know it depends on wheel diameter but If we know a wheel diameter we can transpose to another.
Or do you know the thread pitch on the tie rod ?
Thanks
Tom
7/5/2010
Thinkin out loud here, I made an error since toe in/out is the difference between the track widths as measured at the leading and trailing edges of the tires or wheels. SO 1/16" toe out would be on one wheel. somehow I convinced myself to use 1/8" instead of 1/16". My revised answer is 1/16' divided by 24 1/2".
Now the Sine = .0025, just shy of 0°-9', or .15°
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