OK - I've searched both the internet and all the different forums, but have found very few sources that list a good concrete methodology. Here's my scenario:

I have a '04 Coupe 6mt. I race in STX (I only have 3 events' worth of experience from last year). I have decided against lowering the car, due to alignment issues, but decided to upgrade what I can for better handling.

Waiting to be installed:
- Tokico D-Spec shocks
- REAR 350evo sway bar
- 17x8 FN01R-C wheels & 245/45/17 tires (when the RT-615's get released this summer)

I plan on installing the shocks and rear sway in about 2 weeks or so. It looks like there will be two "test and tune" autocross events that I will be able to attend in March. I'll probably have to run my 18" Pilot Sports if the Azenis don't get released soon.

Here are the questions:

1. With the given setup I currently have planned (rear sway, adjustable shocks, and wider tires) will the addition of a front sway be of benefit? I think the understeer should be pretty well taken out with tires and the rear sway. Will looser shocks in front allow a stiffer front sway & provide better handling? Is that the wrong approach?

2. Front Sway aside the real question is: What is the METHODOLOGY for tuning a setup like mine? What I mean is: what order do things get tuned? Something like 1. Tire pressures 2. Front Sway Bar 3. Rear Sway Bar 4. Front Shocks, 5 Rear Shocks? If so, what are the telling points when you know you've ajusted to far on each?

I realize there is some subjectivity to this but there has to be a more optimum approach to getting the car pretty neutral to begin with. All the instructions I have found are pretty vague.

Please tell me there is some sort of science to this and not "adjust one thing at a time until it 'feels' right." There are too many options to test in one day using that method (especially since the rear shocks are not easy to ajust quickly)!

Basically, I want to be able to install my new hardware and have it set up somewhere in the ball-park so that I can make the most out of my "test and tune" seat time & really dial-in my settings.

Any of you pros have any advice?

Thanks in a advance!

Mike

 

Nobody else seems willing to touch this thread but maybe I can give you an idea what to look for. I don't think any of the settings are going to yield you more then a few tenths on a 60 second course though.

To me, a larger front sway bar removes traction and causes the car to push. Softer front dampening will allow the car to transition weight to the spring faster so the car will feel a little more responsive on corner entry and will tend to flatten out easier on corner exit allowing you to get on the power earlier.

I would start with the dampening first, sway bars and then tire pressure, but adjusting front or rear first is kind of up to you. It's hard for me to decide if I want more front traction or if I would rather remove rear traction, there is a certain point where the cars setup creates too much friction and I just have to try each seperately. There is also a certain point where a stiffer setup or a heavier sway bar would create more traction because the tire isn't rolling over to the outside of its contact patch.

 

Thanks briang35 - this is definately not a "yes" or "no" question.

I would think I should be able to improve by more than a few tenths based on suspension upgrades alone though. I was thinking more like 2-3 seconds over a 60 second course. Otherwise would anyone do any suspension work besides looks?

That makes sense to me---on the flip side, wouldn't a "softer" front sway (like the first setting on the 350evo sways) allow stiffer front shocks be of benefit as well?

I'm still looking for a "by-the-numbers" approach to this. Something like:
1. Set evertying to full soft, and all four tires to equal pressure.
2. Run some sort of course that focuses on one type of steering response like steady-state turning around a fixed radius.
2a. Increase front tire pressure until EFFECT1 happens.
2b. Increase rear tire pressure until EFFECT2 happens
2c. " " front sway
2d " " for rear sway
3. Now do different test-perhaps transient behavior like a slolam.
3a. Increase front shock rebound (the D-specs adjust bump and rebound simultaneously) until EFFECT3 happens
3b. " " for rear shocks
4. Now do a third test and fine tune sways for flavor

This is a generic iterative process , but isn't there something like this that people use? I've ordered a few books: "Drive to Win," "Secrets of Solo Racing," and " Chassis Engineering/Chassis Design, Building & Tuning for High Performance Handling" from Amazon. Maybe they'll have a bit more of what I seek

 

No one else has any methods to contribute?

 

Setup is about knowing what is the right way to do things, where the setup is lacking and how to get the most out of the sum of all the parts. And it's about what not to do. However, don't forget to polish up your driver skills, it's offten said that the sport is 75% driver 25% setup. If you want a baseline starting point, I would start with 35psi, rear bar set at soft, front bar with prothane urathane bushings, on the shocks when installing, I would set them to full stiff, then turned down 3 turns. Then test, looking for faults, take tire temps to confirm.

The books will tell you what you need to know. One thing for sure, order yourself a tire temp gauge, one that touches the tire not just reads the surface temp. http://www.racerpartswholesale.com/long12.htm You need to know the inner, middle and outside readings to verify if your on the road to dialing in the setup in the right directon. Word to the wise, beware of the bushing flex these cars suffer from. The rear radius rod, rear lower control arm (toe adjustment point), rear camber arms and the front upper control arm (upper link) all have soft bushings that allow flex. It would make sense to kill off these flex points off so they cannot effect geometry change when the suspension is loaded. This is why Jic, Stillen and EVO350 offer rear camber arms with sperical bushings and a non adjustable rear radius rod also with a sperical bushings. EVO350 and PerformanceNissan offer their front upper control arm with sperical bushings. Protocav is working with a local shop to have them machine sperical bushings for the oem upper control arms, pm him on my350Z.


http://www.grmotorsports.com/repent.html

http://nicoclub.com/zerothread?id=100871

http://www.ingallseng.com/performance/primer.html

http://www.nyracer.com/tiretemp.htm

http://www.nyracer.com/overunder.htm

http://www.sccaforums.com/cgi-bin/ultimatebb.cgi

 

Thanks Gsedan35! That does help. I'm starting to develop a plan as we spak. I'm still 50/50 on getting 350z springs, but I think I am gonna get the front 350evo sway now... I just want to maximize my test and tune time so I'm not fixing one thing and making 3 others much worse then wasting the whole day trying to get it back together. Thanks for the info!

 

I didn't want to rock the boat since your pervious post said you were sticking with the oem front sway bar, but I do feel some increase in front roll bar is warranted on these cars. Just not full stiff and med stiffness only when testing proves it's value.

 

Yep, I'm starting to think the same thing after I've started some reading. The 350evo bars are not nearly as stiff as some of the others. At the same time, I think they the best adjustability within their ranges. See if this holds water (I got the 350evo rates off a post from a while back):

Sway (setting)__Front____%OEM Stiffness__Rear____%OEM Stiffness
----------------------------------------------------------------------
Stock__________1137________100%_______385________1 00%
350evo (1)______1014________89.2%______362 ________94%
350evo (2)______1207_______106.2%______451________117.1%
350evo (3)______1460_______128.4%______578________150.1%
----------------------------------------------------------------------

Possible combinations result in different Front to Rear Balances. I calculated these by dividing the front by the rear (using the smaller as the denominator). The average was calculated by averaging the two %OEM stiffnes rates from the table above.

Front__Rear___Balance Transfer__Average Stiffness Increase
--------------------------------------------------------------
1_______1_____5% to rear_____________-8.5%
1_______2_____31.3% to rear __________3%
1_______3_____68.3% to rear __________19.5%
2_______1_____12.9% to front__________0%
2_______2_____10.3% to rear __________11.5%
2_______3_____41.4% to rear __________28%
3_______1_____36.6% to front__________11%
3_______2_____9.7% to front___________22.5%
3_______3_____16.9% to rear __________39%
--------------------------------------------------------------

If I did this correctly, I would have to guess the best combo for my autox setup will be 3-3 and if it pushes, then a 2-3 should do the trick. Then back to 1-1 for touring or 2-2 for aggressive street driving. Obviously these are guesses and will have to be tested somewhat. What do you think?