Page 1 of 1

how do i fight understeer ?

Posted: Sat Feb 13, 2010 7:13 am
by jdmellor28
ok kinda sounds dumb but i wish to fight understeer !

what do you think i should do for this ?

i had a random idea ... put wider tires on the front than on the back ?

like front would get 225/45/17 and in the rear you put 215/45/17

would the side wall hight still match from wider to thinner ?
im not good with math i do know its proportional though.

Posted: Sat Feb 13, 2010 6:34 pm
by evolutionmovement
No. 225(.45)=101.25mm, 215(.45)=96.75mm. Not only that, but you'd be unable to rotate the tires unless you get non-directional, probably non-performance tires or have the shop dismount and remount them on the opposing side every few thousand miles, so it would cost you one way or the other and may not make the difference you're hoping for anyway.

You will never completely eliminate understeer unless you make the car have undriveable oversteer, which it would probably snap transition to as the changes you would make would have to be dramatic, but you can reduce it. First thing is tire pressure—lower in the rear. Probably won't make much difference, but it's free. The next is to learn to drive around it. I can pivot the wagon on its front tires for tight turns if I come in hot and get the left-foot braking right. The left-foot braking technique works fairly well within a turn as well. Next, is where the money comes in. Better performance tires will raise your margins before understeer. A stiffer rear bar will make the car tend more towards oversteer. You could kill an obnoxious neighbor and keep them in the trunk for more rear weight bias, but damn decay means you'll run out of neighbors as you have to replace them and they'll likely be of variable weight (but that does leave less people to complain of the smell). I guess a couple bags of cement would work for that, too, but the weight will hurt acceleration and, if truly effective, would cause instability under heavy braking. Probably wouldn't do that much anyway as an engine in the back of my wagon was barely noticed, though I didn't drive on the limit with it back there.

Posted: Sat Feb 13, 2010 6:45 pm
by gijonas
Take the front axles out?

Alignment makes a big difference too,if you can find a shop that will custom align your car you could get good gains there.You may need some adjustable rear links though.

Posted: Sun Feb 14, 2010 12:34 am
by ciper
I assume you have an open rear differential? An LSD goes a long way to help.

Why not try giving the rear wheels some toe out?

Have you installed a larger rear sway bar?

Try running the front tires at 29psi and the rears at 40?

You can run two different size tires but not the sizes you gave. Like evolutionmovement said above they have a significant difference in diameter.
225/45r17 translates to -
225mm wide with a sidewall of 45% that size on a 17 inch (431.8mm) diamater wheel.
That makes a circle with radius of (101.25 + 431.8) / 2 = 266.525 vs 264.275 for the other tire.
So cirucmference is 1674.6 vs 1660.5 or more than a half inch difference.

You could try 205/45r17 and 225/40r17 since they close enough to match (either could be larger than the other depending on tire choice and pressure)

Posted: Sun Feb 14, 2010 7:35 am
by jdmellor28
yes ... im sad to say i do not have the lsd . my dad has the lsd , but not for long ! haha im gona need to trade him !

i am working on the alignment .. gona do a lot of new stuff ( tie rods , ball joints , sway bar endlinks ... and more ) then take it in for the alignment !

i have heared about the rear sway bar ! but i never saw what one i should get ?

- what sway bar should i put on the rear ???
- and any idea where i can buy a rear strut bar ??? it cant hurt !

i will be doing front fender braces also !

Posted: Sun Feb 14, 2010 9:45 pm
by kbeefy
what car do you have?

+1 for upping the rear swaybar. I have the whiteline 20mm adjustable and like it.
AntiLiftKit also helped.
stiffer springs (at least in the back) will help as well.

Failing all that, simply unhooking the front swaybar helps as well, but you probably won't like it in high traction environments (dry pavement), especially if you still have the stock springs.

Posted: Sun Feb 14, 2010 11:13 pm
by Redlined
what are your intentions for the vehicle? Rally? Auto-X? straight street driving? Drift?

For most of the above an alignment and swaybar will do you fine. As you push harder and turn faster our cars move from mild understeer to a really neat oversteer that is nicely controllable. changing a cars basic footprint will exagerate that as your skills/speed increase.

If your just tooling around a parking lot, or want tons of Over-steer for drifting kill the front sway bar put poly bushings on the rear and play with tire pressure.

If your planing on higher speeds you donlt want to change the basics to much or you'll find yourself going through a corner backwards at unseemly speed as additional momentum/centrifigul force multiply the effects of the changes youve made.

Lots of good info on this sight and lots of Knowledgeable people. but you have to remember what YOUR end goal is and adjust as necessary.

Posted: Mon Feb 15, 2010 6:06 am
by jdmellor28
well ...
i drive a 1994 turbo legacy
my car has : wrx struts and whiteline wrx wagon lowering springs
i have wrx front brakes . and i just got some 17s that have not been on the car yet . as of now i run wrx wheels and some crappy tires .

my end goal is to be able to corner like a pro on back roads around home, and mountian roads when i go on road trips down south.
Im also looking to do time attack every once and a while.

i love drifting but i just kinda plan to buy another car for that . as i have had a few RWDs in the past to play with .

i will play around with my subaru for sure ! but it sounds like a good sway bar for the rear is in order !

Posted: Mon Feb 15, 2010 7:25 am
by adema2626
jdmellor28 wrote:i love drifting but i just kinda plan to buy another car for that . as i have had a few RWDs in the past to play with.
Could always make your ss Rwd hehehe.

This doesn't really fix the problem of under steer it just makes it so you can use throttle to correct it.

Posted: Mon Feb 15, 2010 8:59 pm
by kbeefy
since you already have springs I think you'll be pretty happy w/ an upgraded rear swaybar and a performance allignment.

Posted: Tue Feb 16, 2010 8:16 am
by jamal
big swaybars and a good alignment go a very long way toward making these cars handle well. I haven't even bothered adjusting my whiteline 22mm rear bar to full stiff.

Posted: Tue Feb 16, 2010 7:35 pm
by Legacy777
jamal wrote:big swaybars and a good alignment go a very long way toward making these cars handle well. I haven't even bothered adjusting my whiteline 22mm rear bar to full stiff.
Same here. I've actually got mine on the least stiff setting.

Posted: Tue Feb 16, 2010 10:21 pm
by Apex3
+1 on sway bars and alignment, take it to a shop that does race/track cars, and tell them it's a daily but you want to reduce understeer. You don't want it to screw up your tire wear too much, that's why I say tell them it's a daily. Changing your toe and camber should help.

Sway bars you're going to want front and rear, rear will make it oversteer more, but the front will still help, plus it's easy to get a 20mm from a newer Impreza wagon.

Don't do staggered tires, that will just screw up your handling.

Posted: Tue Feb 16, 2010 10:39 pm
by jdmellor28
ok fill me in quick on what sway bars will fit my legacy.

you say newer impreza wagon ?

like a 2002 wrx wagon ? i have seen tribeca sway bars for the front ?

what should my shopping list look like ?
Front - make model and year of car to get sway bar from ?
Rear - make model and year of car to get sway bar from ?

what is every one running ? some of you guys said whiteline adjustible ? but for what car ?

Posted: Wed Feb 17, 2010 12:53 am
by Apex3
jdmellor28 wrote:ok fill me in quick on what sway bars will fit my legacy.

you say newer impreza wagon ?

like a 2002 wrx wagon ? i have seen tribeca sway bars for the front ?

what should my shopping list look like ?
Front - make model and year of car to get sway bar from ?
Rear - make model and year of car to get sway bar from ?

what is every one running ? some of you guys said whiteline adjustible ? but for what car ?
Check the suspension thread. I think my front sway bar is from a 2.5TS, but I'm not positive, the guy I bought it from said he thinks they're the same diameter for 2.5s and WRXs, but he said 20mm, and I measured it as that too. You should be able to get them dirt cheap on Nasioc. But only GD wagon sway bars will fit, not sedan.

For the rear I don't believe anything swaps over, Whiteline is the only solution I've found, though I don't have one personally.

Posted: Sun Feb 21, 2010 9:02 am
by kbeefy
whiteline is the only thing I could find for the rear.
Factory SS is 19mm front and rear IIRC

Check the suspension sticky, it's got lots of info....
Basically read all of these:
http://bbs.legacycentral.org/viewtopic.php?t=35322