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Old 06-20-2002, 12:17 AM   #1
Eric SS
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swap and N20. gone. : (

Exclamation Make your handle how you like it!

I posted this in General forever ago but wanted to resurect it in these newer forums where I think it belongs! Enjoy

OK,There has always been a huge debate over what to do if your car oversteers or understeers. The first thing people go to is always the swaybar when someone always asks how to "loosen" or "tighten" their car. However, there is a lot more to making your car handle to your liking, and everything will do a little something different depending on speed, turn-in rate, braking percentage, weight distribution and a number of other factors. To help everyone out, here is a list of things you can do to your car to get it how you want. You might even want to print it out and bring it to the track with you. Here goes:

TO REDUCE UNDERSTEER or INCREASE OVERSTEER:

Front tires:
- Increase tire pressure in 2.5psi increments
- Increase Section Width
- Lower the Aspect Ratio
- Reduce front tread depth

Rear Tires:
- Reduce tire pressure in 2.5psi increments
- Reduce section width
- Install higher aspect ratio tires
- Increase rear tread depth

Front Wheels:
- Install wider wheels
- Install lighter wheels

Rear Wheels:
- Install narrower wheels
- Install heavier wheels

Front Alignment settings:
- Dial in more negative camber
- Dial in More toe-out
- Dial in more positive caster

Rear Alignment settings:
- Dial in more positive camber
- Dial in more toe-out (Same as front)

Anti-Sway bars:
- Soften the Front
- Stiffen the Rear

Spring rates:
- Soften the Front
- Stiffen the Rear

Shock absorbers:
- Soften the Front
- Stiffen the Rear

Suspension Bushings:
- Soften the Front
- Stiffen the Rear

Brake Proportioning
- Reduce Front brake pressure
- Increase rear pressure

Weight Distribution
- Reduce front weight
- Increase rear weight

Aerodynamics:
- Increase Front Downforce
- Reduce rear downforce

---------------------------------------------------------------------------------

TO REDUCE OVERSTEER or INCREASE UNDERSTEER:

Front tires:
- Decrease tire pressure in 2.5psi increments
- Decrease Section Width
- Install higher Aspect Ratio tires
- Increase front tread depth

Rear Tires:
- Increase tire pressure in 2.5psi increments
- Increase section width
- Reduce aspect ratio
- Decrease rear tread depth

Front Wheels:
- Install narrower wheels
- Install heavier wheels

Rear Wheels:
- Install wider wheels
- Install lighter wheels

Front Alignment settings:
- Dial in less negative camber
- Dial in less toe-out (to toe-in if needed)
- Dial in less positive caster

Rear Alignment settings:
- Dial in less positive camber
- Dial in less toe-out (Same as front)

Anti-Sway bars:
- Stiffen the Front
- Soften the Rear

Spring rates:
- Stiffen the Front
- Soften the Rear

Shock absorbers:
- Stiffen the Front
- Soften the Rear

Suspension Bushings:
- Stiffen the Front
- Soften the Rear

Brake Proportioning
- Increase Front brake pressure
- Reduce rear brake pressure

Weight Distribution
- Increase front weight
- Decrease rear weight

Aerodynamics:
- Reduce Front Downforce
- Increase rear downforce



Well there you go. Keep in mind that any adjustment you do will affect the car so do not do more than 2 adjustments at one time. If those don't work or you still want more, keep trying but don;t do to many adjustments at one time. Any question, feel free to ask

Eric

PS: Possibly a good stickie
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Old 06-23-2002, 01:54 AM   #2
Eric SS
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swap and N20. gone. : (

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I can't believe no one cares about this Just trying to clean up the forum a bit.

Eric
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Old 06-23-2002, 06:41 AM   #3
ellisnc
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Did someone say track day

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yeah honestly that should be a sticky
how many times per week does someone come on here and complain about understeer???
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Old 06-23-2002, 11:49 AM   #4
jesse370
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too many times. I found this very helpfull and informative. I'm still waiting for my baby to get here, but I hope that with the sti suspension it will give the car a more neutral feel to it.
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Old 09-12-2002, 02:13 AM   #5
oops
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A bump for someone that has dedicated the last 2 years of his life to helping the i-club only to get temporarily banned.

This is a good thread people. Read it and remember it if you ever have questions like "My car understeers. what should I do?" or vice verse.
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Old 09-12-2002, 05:18 AM   #6
dorifto88
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Old 09-12-2002, 01:04 PM   #7
subysouth
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Default Damn

What'd you do Imprez?

Thanks for the great info.

subysouth
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Old 02-23-2003, 06:47 PM   #8
Eric SS
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swap and N20. gone. : (

Default

Bizzump again.

Maybe you can add this to the threads to note section or something.
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Old 04-04-2003, 01:04 PM   #9
ResQDawg3
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Someone please Sticky this thread!!! I get tired of looking for it all the time.....
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Old 04-04-2003, 02:35 PM   #10
RokketRide
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there is a link to this thread in the "threads of note" sticky
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Old 04-04-2003, 04:39 PM   #11
FuJi K
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IMO, tire pressure should be looked at as "Fine Tuning" because when you're on a race track, adjusting it along with camber settings will give you maximum contact thorughout the race track.

To adjust the tire pressure to it's optimum, you need a temperature probe thingy, that way you can mesure the heat across the tire so you can tell if you're getting contact on the outside (more camber needed), inside (less camber needed), center (lower pressure), or both outside (more tire pressure needed).

Remember, adjusting for AutoX is quite different from Road course i.e Road America, Road Atlanta, Laguna Seca.

FuJi
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Old 04-05-2003, 05:03 PM   #12
Charlie-III
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Hey good job.
I don't need it myself, but it will save me from explaining a gazillion times to other people.
Thanks for the work.
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Old 04-05-2003, 06:14 PM   #13
teiva-boy
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ttt
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Old 04-07-2003, 01:08 AM   #14
Eric SS
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Quote:
Originally posted by FuJi K
IMO, tire pressure should be looked at as "Fine Tuning" because when you're on a race track, adjusting it along with camber settings will give you maximum contact thorughout the race track.


FuJi
Those are just generals. everything listed can be "fine tuned."
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Old 04-07-2003, 03:17 AM   #15
kidatari
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Eric-

Thanks a lot for this post, definately needs to be a sticky. I'm going to print out a copy, and post it on the wall of my garage
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Old 04-07-2003, 11:50 AM   #16
RokketRide
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Quote:
Originally posted by RokketRide
there is a link to this thread in the "threads of note" sticky

do you guys have me on ignore?

this thread ALREADY is a stickie
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Old 04-07-2003, 12:10 PM   #17
vile
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also, some more info to help the subaru community would be to put down the info bout the different cars

i can only speak for the wrx wagon....which has a tendancy to understeer....stock tire pressure is 32 psi front and 29 psi rear.....front sway bar is 20mm and rear is 18mm

and bonus points if you can include spring rates and such
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Old 04-07-2003, 02:45 PM   #18
FuJi K
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Quote:
Originally posted by Eric v2.1


Those are just generals. everything listed can be "fine tuned."

TO REDUCE UNDERSTEER or INCREASE OVERSTEER:

Front tires:
- Increase tire pressure in 2.5psi increments
- Increase Section Width
- Lower the Aspect Ratio
- Reduce front tread depth

Rear Tires:
- Reduce tire pressure in 2.5psi increments
- Reduce section width
- Install higher aspect ratio tires
- Increase rear tread depth


I'm assuming the tire pressure is a cold setting for AutoX. More flex for oversteer, it looks like. PM me your resorces. Okies?

Maybe I'm being too specific and technically too into details. Sorry.....I'm just concerned about the tire pressure thingy because there's talk about it like increasing and decreasing it for AutoX. I understand the concept of it. In road course, the tire pressures are going to be a lot different from Autocrossing courses.

Last edited by FuJi K; 04-07-2003 at 02:55 PM.
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Old 04-07-2003, 05:33 PM   #19
mattf87
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Eric,
Please correct me if i'm wrong but wouldn't you want to add TOE IN up front (instead of the posted toe out), to increase turn in and therefore decrease understeer/increase oversteer?

thanks for the help,
Matt
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Old 04-07-2003, 05:42 PM   #20
FuJi K
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Quote:
Originally posted by mattf87
Eric,
Please correct me if i'm wrong but wouldn't you want to add TOE IN up front (instead of the posted toe out), to increase turn in and therefore decrease understeer/increase oversteer?

thanks for the help,
Matt
My understanding is that Toe-out will increase initial cornering response. Quicker response upsets the vehicle, which when all the components are working together, it'll make your car oversteer quicker.

BUT, IMO it'll not turn as good when the front is under load throughout the corner.
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Old 04-07-2003, 10:08 PM   #21
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That is a great reference, although maybe you should stress that the front and rear tire circumferences have to remain within 1/4" of each other with all the tweaks you can do, on Subarus and other AWD cars.
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Old 04-11-2003, 12:07 PM   #22
Bart
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bump for good info

hudos to Eric v2.1
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Old 04-11-2003, 12:49 PM   #23
ITWRX4ME
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It should be added to the FAQ and Threads of Note in this forum.

Mods, how 'bout it?
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Old 04-11-2003, 01:01 PM   #24
RokketRide
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Its already there

did you read the whole thread?
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Old 04-12-2003, 05:28 PM   #25
MrDisibility
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It should be noted that changes should be made in small increments, making fewer changes at one time will be good too...

Also, keep in mind that the ride is going to be effected greatly by doing a lot of that stuff, especially when stiffening the rear of the car. Also, big swaybars will handle like ass over uneven surfaces. The reasoning for going slowly with it is to get the ideal handling and ride compromise...These are street cars, right?

And I was always under the impression that increasing tire pressure will generally decrease the overall grip. Lower pressures allow the tire to give with the pavement, adding grip when it is stressed laterally. I don't see why increasing front pressure will help them stick through a turn better. Likewise, adding more air in the back would probably help the car rotate better.
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