Tuning for less understeer

[LaureltheQueen]

Okay, so after getting the suspension swapped over onto the turbo and whatnot, I did not find myself taking my regular road test loop without passengers at the right time for some spirited, but safe driving. Finally, a few days ago, I took her for a spin. The rear sway bar helps A LOT in handling, but I'm still having slight problems with a lackage of oversteer. It's hard to explain, I'm really not getting much understeer, but I'd feel a little more comfortable with more oversteer. Just to clear things up, I've got a 92 touring wagon, kyb agx's and whiteline control springs, both products made for the car. My agx's are set at 5/8 in back and 2/4 in front. I cant remember if you want to loosen, or stiffen the rear end to get it to break loose, I THINK it's loosen though. Which brings me to my next problem, to avoid the squeaky chassis syndrome that I got with the 91 L, I wanted to throw in a rear strut bar to make things a bit more solid.

any suggestions?

[THAWA]

what are your tire pressures? I believe every two more lbs in the rear creates more oversteer. Might be every two more in the front I forget.

[boostjunkie]

Stiffen the rear struts and increase pressure in the front tires.

If it's still not to your satisfaction then you could try a rear strut bar and some anti-lift kit components . . . maybe some endlinks for the rear as well as some rear hardened strut top mounts.

Your car is based on a fwd chassis, so it'll behave like a fwd car. You'll never REALLY be able to get it to act like a rwd car under power.

[evolutionmovement]

Whichever end you want to move beyond neutral you stiffen. So in this case stiffen the rear. A rear strut bar might even add a little stiffness back there depending on how beat the chassis is, though I truthfully only eliminated squeaks when I added mine - any difference in handling was unnoticeable. The front bar was a different story.

Playing with air pressures will fine-tune it for free, too. Get a good gauge, though as the cheap ones are almost go/no go gauges rather than tuning tools.

For lots of oversteer you could convert to rwd. Someday when I have a few more cars I may do it for fun. Imagine an old wagon smoking the rears and pitched sideways up the street...

Steve

[Yukonart]

When I autocrossed the Civic last summer, and I was fishtailing (controllably) through the slaloms. . .

I had the Konis set to maximum in the back, and that massive rear tie bar with 22mm swaybar from Neuspeed going on.

That combination did the trick more than you can imagine.

[greg donovan]

im positively sure you want more air in the rear.
check out this link on suspension setups:
http://www.rallylights.com/useful_info/ ... .htm#tires

i have experimented w/this on my rallyx car and the more air i put in the more the car rotates. this was also confirmed by a former prodrive rally tech that i know that is now the head tech/car builder for CPD Racing.

and this may sound really lame but go play gran turismo and buy a fully adjustabe race susp. for you car and play with the settings. the physics of the cars and the effects of susp. tuning are surprisingly accurate.

[NuwanD]

lower rear tire pressures, it really is the difference between the front and rear tire pressures that you should look at... set the front pressures so that you are using all of your tread and not rolling onto the sidewalls... then set your rears about 10psi less than the fronts... and from there adjust to your liking and to the auto-x course... the bigger the difference front to rear the more tail happy the car will be

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Understeer Corrections

Push, plowing, front tires slide out first.
Usually slight understeer is safer.
Raise front tire pressure.
Lower rear tire pressure.
Soften front shocks. Stiffen Bump.
Stiffen rear shocks.
Lower front end.
Raise rear end.
Widen front track.
Install shorter front tires.
Install taller rear tires.
Install wider front tires.
Install narrower rear tires.
Soften front sway bar.
Stiffen rear sway bar.
More front toe out.
Reduce rear toe in slightly.
Increase front negative camber.
Increase positive caster.
Soften front springs.
Stiffen rear springs.
May need more front suspension travel.
Install wider front wheels.
Use softer front compound if possible.
Use harder rear compound if possible.
Remove weight from front of vehicle.
Add weight to rear of vehicle.
Drive a different line.
Use weight transfer to your advantage.
High Speed. Increase front wing downforce.
Too much front brake.

Vehicle is TWITCHY at limit and hard to keep ahead of in the steering department.
Lower front and rear tire pressures slightly.
Suspension may be too stiff.
Shocks may be set too firm.
Tires may be old or hard.
Vehicle may not have enough suspension travel.

Oversteer Corrections

Loose, rear tires slide out first.
Oversteer can be dangerous, especially at high speeds.
Lower front tire pressure.
Raise rear tire pressure.
Stiffen front shocks.
Soften rear shocks.
Raise front end.
Lower rear end.
Reduce rear track.
Install taller front tires.
Install shorter rear tires.
Install narrower front tires.
Install wider rear tires.
Stiffen front sway bar.
Soften rear sway bar.
More front toe in.
Increase rear toe in.
Reduce front negative camber.
Reduce positive caster.
Stiffen front springs.
Soften rear springs.
May need more rear suspension travel.
Install wider rear wheels.
Use harder front compound if possible.
Use softer rear compound if possible.
Add weight to front of vehicle.
Remove weight from rear of vehicle.
Driver may be going in too deep.
Driver may be getting on the throttle to early.
High Speed. Increase rear wing downforce.
Too much rear brake.
Vehicle slides and is easy to drive at limit but does not corner to full potential.
Raise front and rear tire pressures slightly.
Suspension may be too soft.
Shocks may be too soft.
Roll centers may be too high.
Lower vehicle.
Tires may be too hard.
Widen track front & rear.

A properly set up vehicle will usually push slightly on corner entry, be fairly neutral at the apex (STEADY STATE) and exhibit slight power oversteer on corner exit. Tight courses may require more oversteer, fast tracks understeer.

happy auto-xing

[LaureltheQueen]

gracias!

[legacy92ej22t]

Wow Nuwan, nice write up. Very informative.

I think that info would make a really good sticky.

[Brat4by4]

Why in hades would you screw around with your air pressure in a daily driven AWD vehicle?

And honestly Laurel, I think you need to look at your driving style. It doesn't really make sense what you say about your vehicle dynamics.

Drive a different line.
Use weight transfer to your advantage.
High Speed. *edit* Slow down.
Too much front brake.

The problem most likely lies in one of these 4 from Nuwan's post.

[greg donovan]

im positively sure you want more air in the rear.
check out this link on suspension setups:
http://www.rallylights.com/useful_info/ ... .htm#tires

i have experimented w/this on my rallyx car and the more air i put in the more the car rotates. this was also confirmed by a former prodrive rally tech that i know that is now the head tech/car builder for CPD Racing.

and this may sound really lame but go play gran turismo and buy a fully adjustabe race susp. for you car and play with the settings. the physics of the cars and the effects of susp. tuning are surprisingly accurate.

you know what i am obviously wrong. i have been running on about 15 hrs of sleep total for the last 5 days. i know it is the other way from what i said dont know what i was thinking! oh i know i wasnt. sorry for the horrible statement. i even remember now that i lowered the rear pressure last summer. the link i posted is right and is the total opposite of what i said.

sorry,
greg

[NuwanD]

greg; lol.... if i had a penny for every time i did that

in regards to running altered pressures in a daily driver, i don't think most people would run 50f/35r pressures all the time, although i can't say that i haven't ...even with proper corner entry and weight transfer, on a tight auto-x course there sometimes isn't enough room to get the proper rotation around a tight turn and that's where the tire pressures make a world of difference... besides; sliding through a switchback is much more fun than the usual line

[greg donovan]

besides; sliding through a switchback is much more fun than the usual line

thats why i rallyx. i dont need gobs of power to slide!