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Discussion Starter · #1 ·
I am at the point where I can't find anymore ways to increase grip. Can anyone give me any new ideas on how I might meet my 1.0g goal? I have put on trd lowering springs and have maxed out my tire width without scraping my fenders. The only other thing I can think of is switching from a kdw'2 to a kd. .97g just isn't enough for me; I am getting to be a cornering crack head. Money is not an issue here any ideas would be great.
 

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First off, not that I don't believe you, but how/who/where was the testing done that you arrived at your 0.97g figure? I ask this because I'd love to test my own car if possible, not because I distrust your figure.

Secondly, your car may not get 1.0g on a skid pad now, but let's say you find a way to get your car to go around that same skidpad of x diameter quick enough to achieve 1g on it; that doesn't automatically mean better overall handling. Conversely, you may have adjusted the car's suspension to the point where, while the car has been optimized to travel in a predefined circle of a specific radius (or should I say, orbit?
) faster than before, your car may actually have crossed the fine line that makes the car so well-balanced as it is in other driving activities; handling isn't just in the numbers. An alternate, and to me, more important test, is the slalom, as that is a better test of overall balance and control, not just grip around a turn of a certain diameter (and in only one direction, if you haven't tested both directions--I don't know since I have no knowledge of your exact testing methodology). A car can grippier but at the same time twitchier at the limit and/or less refined. A car that can now circle an 80ft skidpad faster than before may suddenly be slower in the slalom due to an off-balance at other steering angles or transients in cornering direction and force. An example of this would be that in many tuning situations, a slight reduction in front suspension firmness might allow sufficient negative camber under cornering load to allow your to reach your 1.0g goal around an 80ft skidpad, but now under transient from one direction to the other, like in a slalom test, your car's responses and feedback will have dulled, making it difficult to achieve a spotless run through the cones, and possibly leading to lower overall speed through the slalom.

I'm not trying to knock on your for asking your question and I know I am not really answering it at all, but I'm just trying to point out that another .03g on a skidpad test average in two directions doesn't necessarily equate to better overall handling, that's all. Even a reduced laptime on a timed course just means you're faster on that track and how it's set up. I'm not trying to diminsh the importance of your tuning attempts either, because in the end, if it's really better, better is better!

Anyhow, my recommendation, other than the sage advice you will likely get in here from a few of our well-seasoned and experienced members, is to check out the short, "Making It Stick," series of articles that were released in Sport Compact Car magazine recently; the information provided there is a veritable fountain of suspension tuning knowledge worth its weight in gold, presented in a well-written format that's short and to the point along with excellent graphics illustrating the stated points in a form that will engage visual learners as well as the literal types.

Btw I'm not trying to be a spokesperson for SCC in any way, but I really love the Making It Stick series of tech articles!

Good luck tuning that ride! It's already pretty damn good though if you're getting close to 1g from a front wheel driver with hardly modified suspension! It just goes to show how well-tuned our cars are from the factory when given proper rubber to prove itself!


-Ed

EDIT: PS, don't forget, that how the car feels is often as important as actual, objective test results. For example, a car that can pull an average slalom at 72mph but is extremely difficult to drive consistently and quickly at the limit is not nearly as good as the same car that's very easy to drive and direct but, "only," gets 70mph in the same slalom, because an easier to drive car means easier repeatability/consistency in the performance of the most important part of any racing equation--the driver (i.e. what's better, you in your own car pulling 72mph through the slalom on the 4th try, but getting no better than 67mph on the first three tries, or you getting 69 or 70mph in every single run out of ten tries?).

EDIT 2: Don't forget other points of practicality as well. I'm assuming yours is a street driven car; I can easily imagine that a car tuned to achieve 1.0g or higher on an 80ft skidpad with suspension still supple enough to drive in comfort daily on real streets may have so much negative camber dialed (particularly in the front of a tC, although factory stock tuning to me looks like understeer city since the rear double-wishbone's stock camber is more negative than the front's macstruts are set for--is the front camber adjustable from the factory on tC?) that tire wear will be uneven since it spends most of its time driven as most street cars are, not constantly in a circle at a preset speed. Everything really needs to have overall balance as the primary consideration before tuning.
 

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Originally posted by Ryan'sTc@Aug 12 2005, 10:10 PM
I used my buddy’s passport G-timer. When I first got the car with 225/35/18 P zero nero's. I got a .91 cold and a .92hot. Two weeks ago Neal brought over his meter again and I scored a .97 turning left. And a .96 turning right.
Ah, so it's the highest figure attained yet to either the left or the right while driving, I got ya'.

-Ed
 

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What's the turn radius? That has a lot to do with grip and lateral acceleration.
 

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The standard magazine circle is 300 feet. Doughnuts don't mean a lot for lateral acceleration.
 

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Find an on ramp that loops 270 degrees or so, or better still, a real cloverleaf so you can loop around successive corners. Otherwise you need to find a big parking lot and set out cones to guide you in a 300' circle and practice a bit before you get all worked up about your numbers. Don't be suprised if they are a bit lower than you expect. You should still be in the .92 - .94 range though with KDWs.

I still have some calculations to do with the tC for roll center and roll couple. Those will also help, but that won't be going until after this weekend. I've also got to get a decent method for determining CG.

EDIT: I sent and email to Hotchkis since I bought their sway bars and asked them for some tech assistance with calculating roll center and roll couple, but they have not responded.

Are you reading this Dr. Isotope? I KNOW you've done this stuff for circle track racing!
 

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Discussion Starter · #10 ·
Originally posted by Ryan'sTc@Aug 12 2005, 10:10 PM
I used my buddy’s passport G-timer. When I first got the car with 225/35/18 P zero nero's. I got a .91 cold and a .92hot. Two weeks ago Neal brought over his meter again and I scored a .97 turning left. And a .96 turning right.
Sorry I made a mistake they were 225/40/18's for the P zero's/
 

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i think you should try h&r springs and you might want to change the shocks to adj. ones. then sway bars.. strut tower braces.... then screw with the tire pressure... tien spring might be good too. i prefer progressive rate springs for daily driving because they are soft until you push them then the rate is a lot stiffer. you might weant to try springs with high spring rates...
 

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I already know what this does. My Supra is on Tein HAs with a spring rate about 80% more than stock. I rides like a buckboard.

I have a set of SS-P Teins for my tC going in tomorrow. The spring rate on them is twice the stock spring. I suspect I'll be pretty unhappy with the ride quality, and be ordering another set of springs before the end of next week to be sure the ride to Atlanta isn't too stiff.

We need to build a chart with the various spring rates and free lengths on it so we know what we are buying.
 
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