Circuit Suspension set up

Road race, Auto X, or the Drag Strip

Postby CMS-GT4 » Mon Mar 16, 2009 5:56 pm

I was hoping if I got a stock alignment at the shop that I could add some camber for events and put it back to zero for normal driving.
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Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
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Postby solarinsocal » Mon Mar 16, 2009 7:10 pm

You might be able to get away with doing that if you accurately mark the position of your tie rod when it's at stock specs and again when it's at race spec. Still, one half twist and your toe is going to be off but at least you'll be in the neighborhood. Or just bite the tire bullet and keep it at circuit spec all of the time which is what mine is at but mine is also not a daily.
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Postby gt4tified » Mon Mar 16, 2009 7:21 pm

As we're on the subject, who sells adjustable camber bolts for the rear in our cars?
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Postby solarinsocal » Mon Mar 16, 2009 9:28 pm

I believe a universal type of eccentric bolt is readily available. Let me ask around and see what I can come up with, though I am satisfied with my rear camber at the moment and have no need to change it. :D
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Postby CMS-GT4 » Mon Mar 16, 2009 10:04 pm

So did you get to test your new settings on the track?
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92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
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Postby solarinsocal » Mon Mar 16, 2009 11:12 pm

Yes, we did get the car out to the track and the result was not what I was hoping for. Still lots of understeer. I have a lot of tuning left to do in the suspension though. I think I will be able to dial a lot of it out with a stiffer rear setting as well as a stiffer sway bar. I believe an LSD will go a long way toward more neutral handling as well. The tire sizing is okay and it does have decent initial bite at turn in but still not what I am looking for.
In the future I will be looking at 17x9 with 255 tires. Too bad you don't live closer so that we can work the kinks out of our cars. I am also looking into upgrading the brakes as they are not up to the task. I read somewhere that you tried to use the STi rotors. Did that fit? How was the backspacing. I have a guy who can CNC brackets for me so I need a rotor to build off of. It might be the solution you were looking for as well.
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Postby CMS-GT4 » Mon Mar 16, 2009 11:23 pm

I have Sti rotors but I have not made the brackets yet. They are a little more shallow than a st205 rotor and a 5mm spacer. One guy in Cali used the st205 calipers, but I am thinking of selling my calipers and use wilwoods instead. The rotors fit fine, they just need a small ring or peice of metal around the hub to make them hubcentric.

Are you planning on a street tire or race tire? A 255 street tire might be way too heavy. I will likely be going to a lighter 245 tire & lighter wheels next time around.

Here are pics of the bracket the one guy used for the 205 calipers. If you have a cheap solution for brackets for a wilwood caliper that would be great.

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Postby gtfour77 » Tue Mar 17, 2009 7:17 pm

I received you pm and wanted to comment quickly about the settings. I have not read the entire thread yet due to lack of time... I will be back in posting action in a month or so...
Your settings are going to be much different for track racing compared to my "strictly autocross" setup. I know our cars can oversteer but many times our cars are over-driven and pushed into understeer. For track racing I'd rather have understeer rather than push the envelope of oversteer.
Also each car will react differently to springs depending on what else you have done. Roll centers, CG height, tire width, pressures, shock settings will all play major roll in spring stiffness decisions.For a stock RC and slightly lowered CG I'd stick with something like 550 lb springs up front and about 350 or 400 in the rear for autocross, for track I'd go with a slightly lower rear spring and stiffer front bar. This will all depend on your rear bar, settings also... Testing, testing ad more testing is the answer... and don;t forget to tune for your particular driving style, this is what many people forget. :wink:
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Postby solarinsocal » Wed Mar 18, 2009 12:37 am

Thanks for the reply. I am looking forward to picking your brain in the future. :D Thanks.
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Postby CMS-GT4 » Wed Mar 25, 2009 4:18 pm

I am wondering how much your softer rear springs affects your cars handling vs mine. Did we ever explore if you had a rear lsd as well? On that same note, how many miles are on your gearbox? Since you want to race this car I am curious how old your VC is and if you would see any improvement with a fresh center VC at mid turn/exit.

Also, if you get bored, you mind seeing what that document says about the shock dyno for the HAs on the previous page.

Also, one of the best mods I was able to make on my car apart from the teins was the rear whiteline sway bar.

On a related note, what year is your 185? 92+ got a larger front sway bar. This is another thing to consider when setting up the car. There was a 205 member a while back that had a larger front bar made, and I think whiteline offers a larger front bar for the celicas. We just have to determine the diameters of the stock front bars and how they compare to the whiteline version.
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92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
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Postby solarinsocal » Fri May 08, 2009 3:33 pm

Just got back from a track day at the Streets of Willow running configuration 13. I had some issues during the day such as cracking my passenger side front wheel going through the esses off of the back straight so I was then left with my back up set of 16 inch wheels running mismatched no name tires sized 205 50 16. Anyway, I took some in car footage but the file is just too large to post. I was running in the expert class and everyone should be happy to say that the All trac held it's own. I did get passed by a few cars including the GTR, Porsche GT3RS, a BMW widebody with 750hp (passed me like I was standing still), and one very fast S2000 but I took down quite a few STi's and Evolutions. In my current set up running my 17 wheels and tires (until the front one exploded) was that I am still suffering from understeer on turn in which is most likely the tires that I am running combined with a too soft damp rate and spring rate. After turn in, the car is neutral to oversteer unless on the gas at exit which returns the car to understeer. Exit understeer is not particularly bad if you calculate the amount of drift to the outside through the corner since the car is still accelerating. Once I swapped wheels to the smaller 16 inch, the car became very loose. You can actually see me oversteering on certain corners in the video. The car actually had better turn in but that was due to the rear stepping out on off throttle and trail brake transitions. To summarize, the car in it's present state is no where near being able to compete. The spring rates that I am using are not up to the task and the car is just entirely too overweight. If anyone can tell me how to post videos then I may be able to do so if anyone is interested.

CMS-GT4- I'll see if there is any pertinent information on the Tein page for you.
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Postby CMS-GT4 » Fri May 08, 2009 5:15 pm

Good feedback. I am wondering if it was the increased side wall of the 16's that changed your handling characteristics.
What kind of weight reduction are you looking at?
There is a good thread that give you an idea of what you can pull.

AC (80lbs), backseat(20lbs), sunroof(40lbs), and racing seats (~40lbs saved over stock power seats) combined could almost drop you a couple hundred lbs.

Then there is always the CF hood, CS front crash bar for lighter front components. If its not required, you could always toss the rear crash bar like the rally cars and just keep the bumper cover on. Though, it might not be good for the car if you get rear ended.
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
www.noritoy.com | noritoy.deviantart.com | http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=19891
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Postby masco » Tue Jun 02, 2009 6:45 am

I agree you must lighten the front end of your car. You should install the RC front bumper or at least the aluminum crash bar if you haven't already. As for springs try 10 kg/in f and 8 kg/in rear before you put the 12 kg/in springs in the front. You seem to already have bushings and a thicker rear swaybar so that is covered.
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Postby ccsouls » Wed Jun 03, 2009 6:32 pm

Wouldn't you want to make the rear stiffer to take the understeer out and bring the rear around?

I would think perhaps trying to make the rear spring settings somewhat closer to the fronts might help.

I know some of the STIs I run against in SCCA have 500lbs front and 550lbs rear.

Am I missing something?
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Postby CMS-GT4 » Wed Jun 17, 2009 4:59 pm

Check out what Roundy did with caster.

It may help you.
http://www.alltrac.net/phpBB2/viewtopic ... 14649e1d33
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
www.noritoy.com | noritoy.deviantart.com | http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=19891
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