heyma

Hi,

We have a 93 SC400 and I was wondering what "cures" are out there to limit the oversteer these cars sometimes exhibit. I'm not looking to eliminate it, as a neutral handling car is what I like. But there's no reason the car should dangerously oversteer at less than high speeds on wet roads.

My current setup is 17" rims with Nitto NT450 tires with less than 10k miles on them; size 225/17/50. I suspect the tires are a big reason for the rear-end coming around in wet, sweeping turns at moderate speeds - not once, but twice.

I'm not looking for rear sway bars, as that only tightens the rear end up. Are the rear suspension bushings on these cars problematic?

So other than getting better tires, what other adjustments have you guys/girls made?

Thanks in advance for the help.

Simpson

97SC300

toyota designed these cars to understeer alitte bit since they dont want people spining out and crashing. so id check the whole suspension for worn out bushings. and try not to drive so fast in the mean time.

SupraCoup3

you've got an open differential, so if one tire begins to break free, it gets all the power... so you'll just spin the bad boy bigtime.

vssc400 (think that's his SN!) just installed a LSD in his 400, and he said it made a huge differance... of course he's got 265s out back

an LSD would be a good start... my STB really helps, apperently other people are having a hard time with the fitment, but I really haven't, you need to be careful, because the SC400 has different clearances.


Just a few thoughts.

RobSoVIP

the SC4 actually tends to have too much understeer on dry road for my taste. However, like you mentioned, it does have oversteer on wet roads- but heres the kicker... most rwd cars have oversteer on wet roads. Just dont hit it too fast around corners.

SDSC300

how old are you shocks and springs, that might make a little difference if yours are really old/bad.

but the biggest thing is your alignment I am guessing you need more Negative camber, and before everyone starts crying about going through tires like mad, up to 2deg. won't affect that much.

go get your car aligned and have them add some negative camber. that should make a noticeable difference. even if your car still over steers too much.


there might be a few people on here that know good specs for handling. try to find out

VSsc400

iTrader: (1)

tire rack has a good section on their technical section(free) and they have a guide to changing the characteristics of the car.

http://www.tirerack.com/about/techcenter.html

look in there. Just changing tire pressures can affect the way your car behaves... gradually make one change at a time and take careful notes as for you may want to go back to a previous setting.

good luck.

the LSD does make a good bit of difference... but on LSD equipped vehicles once the car oversteers it's easier to lose control...

wider tires on the back during rain can also make your car hydroplane and make the car less stable. Thus on snow tires you generally want to go very narrow tires.

follow those procedues and i'm sure you can find a happy medium.

good luck.

P.S. of course you can get coilovers and start playing with those settings also...

heyma

Thanks for the replies guys.

I think the top two things I'm looking at are to get a more agressive alignment (more neg. camber as SDSC300 suggested) and going to 235/17/45 tires. The reason for the slightly wider tire is that 225/17/50 is a TOUGH size to shop for and there are many quality tires in the 235/17/45 size. And being that it's only slightly wider, it should be ok.

So does anyone have tried & trued alignment specs for these cars?

Thanks again.

P.Williams

iTrader: (1)

You may want to consider the Daizen Sway Bars. The front bar is 35mm which is considerably larger than stock, and will provide some more understeer. The rear bar is also adjustable, so you can set it to your tastes. I have the rear set to the stiffest setting, and coupled with my suspension setup and wheel/tire combo it actually has more neutral handling characteristics than stock. It will corner nice and tight, but won't oversteer unless I add throttle. The biggest problem I had with the stock suspension was the body roll at the back end. The car has a huge, heavy rear end and once it begins to go, it's hard to stop it. Once I'd manage to correct it, the rear suspension would snap back and level out. Now it's far more controlled, and any roll is progressive making it easier to determine the cars limits.
When's the last time the car was aligned? You may be running a bit of toe out at the rear, which will cause the car to step out.
Lastly, if you plan on sticking with your current wheels, you may want to look into some wheel spacers for the rear. This will effectively widen the rear track and should help stabilize it

Lexiss_sc430

iTrader: (2)

I would just say get wider tires, I am running 245's and I rarely get the backend to swing out, unless I purposely want to. I think that the 225's are a bit too narrow especially in wet conditions.

Tommy

P.Williams

iTrader: (1)

I agree with lexiss, larger tires would have been my first suggestion. However, it sounded like you didn't want to invest in a new set of wheels and tires. I think the greatest single improvement in handling is found with a good set of wheels and tires. But it is also one of the most expensive. How wide are your current rims? You may be able to fit 245/45's at all four corners. That ought to help a lot. I'm currently running 245's in front and 275's in back, and there's always plenty of grip when I need it.

Buttercup

Wide tires will give you good dry cornering, but it'll suck on the wet. That's because when it comes to wet handling, tires operate best when there's a lot of pressure on the contact patch, that is weight of car over smaller contact patch.
So you either have a lot of weight on the tires for a given tire contact patch, or you have a smaller contact patch for a given weight.

SO... the easiest fix is to check your tire pressures and bring them up a bit more than spec. That will decrease your contact patch so you get more pressure on the tires so the water won't seep in and hydroplane.

Just give it a try if it'll ever rain this season. Or you could dump water all over the street and see how easy it'll be to spin the tires when accelerating from a stand still.

P.Williams

iTrader: (1)

This is true. However, the tire you choose has to be taken into account. My tires have behaved well in the wet despite how large they are. In fact I've not encountered a single instance where I've been at a loss for traction, with the exception of maybe hard acceleration from a dead stop. I'm using Yokohama AVS db S2's, which is an all-season tire. It has good rain channeling. I live in St. Louis where we get maybe 1-2 weeks of snow per year, but plenty of rain. So, I chose to go with an all-season/mud & snow tire to use year-round. I usually set the tire pressures at 34 psi. Slightly higher than recommended tire pressure will provide better performance in either dry or wet conditions, at the expense of ride comfort.