Alignment/Suspension tuning/Curing UNDERSTEER

[Var]

My s13 has an understeer problem. i've tried several thing to cure this understeer but it wont go away

here are some of the things i tried


1-full negative camber in the front as much as camber plates allow.

2-raised rear end up to reduce rear negative camber

3-put stickier tires in the front

4-got stiffer springs in the rear

5-set adjustable sway bars full soft in the front and full stiff in the rear

6-lowered front end of car




the problem i have is not understeer at steady state cornering, but at the turn-in. i've tried many different driving techniques like trail braking, off-throttle turn-in, abrupt turn in, smooth turn in, weight transfer out-in....i'm so pissed off at this that i'm buying an ae86 now...but i still dont want to give up on my s13.

My real question has to do with front toe setting. I've read that toe-out is good for autocross and toe-in is good for high speed turning..well i dont care what's good for what. i just want to stop the turn-in understeer. how much toe can i run without absolutely shitting on my tires(es100's) i'd like to get 15,000 miles out of them. i got 10,000 miles out of my azenis. and which way should i toe in the front, out or in. thanks...Oh also is toe measured in degrees or inches?


while i'm at it... i'm getting tein tension rods and i plan to run ~8.5 or 9 degrees of caster...i dont know if this help understeer..i doubt it.

[s0ldats]

try all stock/neutral settings first and figure out what you're doing wrong. no offense intended, but it could be a simple driving error. at first i got ridiculous understeer and thought it was my settings but i've just kept practicing techniques and came over it.

if you're cock set on trying more settings, fiddle with the tire pressure. but seriously think about practicing more technique.

[Var]

Originally Posted by s0ldats

try all stock/neutral settings first and figure out what you're doing wrong. no offense intended, but it could be a simple driving error. at first i got ridiculous understeer and thought it was my settings but i've just kept practicing techniques and came over it.

if you're cock set on trying more settings, fiddle with the tire pressure. but seriously think about practicing more technique.

i would agree with you except other cars that i've driven dont do it..not even mustangs .just the fuckin stupid s13

[Replicant_S14]

Originally Posted by s0ldats

at first i got ridiculous understeer and thought it was my settings but i've just kept practicing techniques and came over it.

Same here. Even now, it takes a conscious effort on my part to not understeer entering corners. Brain-fade for a half a sec and.....rrrrrrrppppppppp!!!!!!!!


EDIT: just for s**ts and giggles, disconnect the front sway bar and see what happens.

[DuffMan]

S13 tends to understeer at turn in due to the front suspension geometry. The roll center of the MacGayson struts too low, and it gets even lower when you lower the car.

Whitelines solution for this is to use a large sway bar in front, but less stiff springs. On whiteline springs the back is actually slightly stiffer than the front. This improves the turn in response, but keeps the rear end in durring and exiting a turn.

I don't have a whiteline setup but I'm trying to do something similar, but stiffer. I sold the 8kg/mm front springs on my TEIN HE's and want to replace them with 6kg/mm or similar springs. Then I will get a 30mm or bigger front sway.

[s0ldats]

out of curiosity, what kind of suspension do you have right now? shock/spring or coilover?

[Rennen]

Originally Posted by westboroughpimp

1-full negative camber in the front as much as camber plates allow.

2-raised rear end up to reduce rear negative camber

Depending on what "full negative" is, you might have decreased your front contact patch and increased you rear. Other than that, try less corner entry speed and/or smoother braking. One summer of autocrossing has taught me to keep even my stock S13 from understeering heavily. "Slow in, fast out"

-Matt

[Var]

Originally Posted by DuffMan

S13 tends to understeer at turn in due to the front suspension geometry. The roll center of the MacGayson struts too low, and it gets even lower when you lower the car.

Whitelines solution for this is to use a large sway bar in front, but less stiff springs. On whiteline springs the back is actually slightly stiffer than the front. This improves the turn in response, but keeps the rear end in durring and exiting a turn.

I don't have a whiteline setup but I'm trying to do something similar, but stiffer. I sold the 8kg/mm front springs on my TEIN HE's and want to replace them with 6kg/mm or similar springs. Then I will get a 30mm or bigger front sway.

duffman thank you for this info.
you're the first person to ever explain this stuff. i knew there was something quirky about s13's in general.




i've been posting about this problem on the forums for god knows how long, and ppl just keep saying "learn how to drive"

well fuck everyone. i've driven a bunch of different cars and no other cars do this. thanks again dude. i got an extra pair of ground control springs laying around somewhere. i'll replace the front 6.7K with 4.5K and set my front sway bar stiffer. If this solves my problem i swear i will be your best friend. thanks again.

[Var]

Originally Posted by Rennen

Depending on what "full negative" is, you might have decreased your front contact patch and increased you rear. Other than that, try less corner entry speed and/or smoother braking. One summer of autocrossing has taught me to keep even my stock S13 from understeering heavily. "Slow in, fast out"

-Matt

no i said full negative as far as camber plates allow which is about 3 degrees max.. i can still shred the outside edge of the tire when the car plows.


how do make the roll center of the car higher?


and why the fuck do all coilover companies sell their kits with the front springs stiffer than the rear? fuckers

[holisticbeatz]

Pull the hand brake

[Var]

jump off a bridge

[nightwalker]

hmmm....I have Tein HEs, a hicas rear sway bar, front and rear strut bar, subframe bushing inserts. No understeer. Kind of odd huh? I think your problem might be in your suspension setting. I set my cousin's car exactly like mine, calculating in his extra weight, and he has no understeering either. You might want to check your camber, because too much camber is not good.

[Replicant_S14]

Originally Posted by westboroughpimp

i've been posting about this problem on the forums for god knows how long, and ppl just keep saying "learn how to drive"

well fuck everyone. i've driven a bunch of different cars and no other cars do this.

God cursed your car. There can be no other explanation.

[Var]

honestly that's what i was thinking.

nightwalker..3 degrees negative isnt too much is it? between the tire sidewall flexing and body roll i think i compensates. maybe i just need an alignment again..?? you know i let convince ppl it was all in my head but then i recently found out drift king says s13's have wierd understeering too. that stamped the seal of approval on it.

[Replicant_S14]

Originally Posted by westboroughpimp

honestly that's what i was thinking.

nightwalker..3 degrees negative isnt too much is it?

what's your rear camber? Any funky tire sizing, spacers, offsets etc?

[Var]

my original question was never answered

how much toe can i run in the front without it being excessive wear on my tires? and toe in or toe out?

[Var]

Originally Posted by Replicant_S14

what's your rear camber? Any funky tire sizing, spacers, offsets etc?

rear camber is prolly 1.5 negative. front is about twice that. no offset problems. tire sizing is 205-50-15 all around except stickier in the front.

maybe i just need to get an lsd and power through turns sideways to go faster.

[Rennen]

Originally Posted by westboroughpimp

no i said full negative as far as camber plates allow which is about 3 degrees max.. i can still shred the outside edge of the tire when the car plows.

What pressures are you running those front tires at! I have stock camber settings and still don't get all over the sidewalls of my Azenis at 40psi, even when understeering.

Also, your car's setup must be truly fucked if you can't trail brake or lift throttle oversteer into a corner, I suggest going to an alignment shop and having them set everything back to stock specs.

-Matt

[Var]

i can get it to oversteer if i want. that's not what i want . . i want it to not understeer and not oversteer but turn in faster with full traction.

how about this idea...lmao

275-45-17 in the front with a 3 inch spacer
225-45-27 in the rear

[s0ldats]

funky toe in the front will cause your car to have bad turn in characteristics. make sure it's even on both sides. people like to have a little toe out in the front for auto-x.

[mbmbmb23]

Originally Posted by westboroughpimp

and why the fuck do all coilover companies sell their kits with the front springs stiffer than the rear? fuckers

Because the front of your car is heavier (engine) than the rear...and due to inertia the front only gets heavier when you hit the brakes. If the front springs were the same as the rear, the nose of your car would dive terribly under hard braking and body roll in the corners would be worse.



-m

[Red]

Originally Posted by westboroughpimp

i can get it to oversteer if i want. that's not what i want . . i want it to not understeer and not oversteer but turn in faster with full traction.

how about this idea...lmao

275-45-17 in the front with a 3 inch spacer
225-45-27 in the rear

Well that’s definitely an idea... Not a good idea, but still an idea.

You would be the only S13 to look fwd.

[nightwalker]

If you play with your suspension settings, (granted you have adjustable shocks, and stuff) You'll notice that the stiffer you set the rear, the more oversteer you get. I ended up setting mine up to about 5-6 clicks down from stiffest for my front, and just one click softer for my rear. No understeer. Even people who ride with me can tell the rear end wants to push itself around.

Too much camber in the front can hurt too. Not enough contact, and all you're going to do is plow. Play with it a bit. If you want to really set it right, get a pyrometer, and check your tire temps.

Other things to consider are spring preload in coilovers like the Tein HE and JIC Flta2s. And sway bars. Struts and sway bars will make the most difference in handling.

[TBreu007]

If you're at full negative camber in the front, your toe goes all out of wack. I'll bet anything you're toed-in in the front really bad. If you're getting understeer at turn-in in a 240sx, there's something really wrong! Get an alignment and see what happens. In race setup, I run front -2.5 camber and around 1/16th toe out...rear is -2 degrees camber and 1/8th toe in. I'm probably going to run a little more toe in for the rear because the car is jittery under braking and high speed corners.
There is really no need to run excessive caster as out cars already have a lot stock. When all else fails, then you mess with caster.

[mrmephistopheles]

i second Replicant's idea of disconnecting front swaybar. My car was pushing all over the place @ last DD, and I'm 75% sure it was due to my front bar (whiteline, softest setting). I'm disconnecting it for this weekend's DD. I'll let you know what happened.

[ridebmx]

for normal driving i was under the impression you should have alittle toe in on the front, as when you are driving you actually get pulled out some(wheels) to me it seemed logical. but again im speaking of normal driving, if i am infact correct, then dont forgot to allow for the little bit you will have to toe in, (could still have alittle toe out)

[DuffMan]

Originally Posted by westboroughpimp

no i said full negative as far as camber plates allow which is about 3 degrees max.. i can still shred the outside edge of the tire when the car plows.


how do make the roll center of the car higher?


and why the fuck do all coilover companies sell their kits with the front springs stiffer than the rear? fuckers

Making the roll center of the car higher is tough. It gets lower the more you lower the car. I'm not saying you shouldnt lower the car, but its a trade off. You need the front control arm to angle up more. BMW's and Porsche's have front struts like a 240sx, but they positioned the mounting points better. There is a product I think works by relocating the front ball joint lower down. I dont know much about it though, but it exists in Japan. In the rear you can buy an adjustable RLCA like SPLparts sells, but its $$ and the front is where the real problem is.

The higher spring rates in front is because the front has more tendancy towards roll due to the poorer geometry of the struts vs. multilink. You do want the front stiffer than the back, I think its just better to do it via sway bars than springs. The sway bar acts progressively the more you roll, so when iniating a turn, the back is stiffer compared to the front and it doesnt understeer as much.

[nightwalker]

I don't understand how you guys with whiteline sways are getting understeer. I setup my cousin's car (whitelines, HE) and his car had no understeer. I don't understeer either. There is probably more to this than we are assuming.

[adey]

For what it's worth, I seem(ed) to have at least some strain of the same chronic understeer that you describe... nothing I've tried so far has helped!

I have come to the conclusion that it is probably my driving style, which has seen no "proper" training other than reading 1/2 a book and having had an instructor sit with me for 3 or 4 laps on a track day.

Thinking a little bit more... do you have a 2-way LSD? If you do, that would be a very probable cause for your turn-in understeer.

Otherwise, I might suggest trying drastically different driving styles (in a safe environment of course) and/or driving instruction. At very least, have an instructor (or otherwise VERY knowledgable/experienced) driver sit by you when you drive to try and help diagnose the problem.

[Var]

maybe we are all talking about different levels of driving. On track, although i've never been there, i dont think my car would understeer at all. When i'm trying to drive fast through the mountain, my car understeers on anything below 50mph. after 50mph, the car feels neutral and can easily be made to oversteer. TBreu007..you may be right about my aligment being out of whack cause i never got it aligned after the camber plates , i just set them full negative.

i want my car to be able to pivot 90 degrees at lower speeds without underteering and as fast as i want to turn it. LIKE A COROLLA>>to those who care i bought one yesterday night. anyways back to ghey understeer. what about ride height..i have my ride height setup so the fender gap in the rear is more than the front by about an inch. i thought this would help but ehh. not so much. i think the biggest help was stepping up from 4.5K to 5.5K springs in the rear.

Duffman: if you know anything about those things they have in japan to fix the roll center link it to me.