BreakTheStatic

I don't really do much highway driving, however this past weekend I went on a few longer trips and I started to notice that the car seems really unstable when doing like 65-70mph. I always noticed the steering's sensitivity on turns, but now even when the car is headed straight (on level ground) any correction w/ the steering wheel results in exaggerated motion. I thought it could be the alignment, but when my hand is off the wheel, the car tracks completely straight on a level surface. It's only when I have my hand on the wheel doing slight movements. I have a really hard time keeping the car going straight along its intended path. I know this extremely subjective, but I've never had a problem w/ this in any other car I've ever driven in. Does anyone have any suggestions on what it could be? I thought that maybe the wheel could be warped or maybe the tires aren't balanced, but those would cause more vibration, and the car doesnt vibrate at all...

Dr_Isotope

iTrader: (1)

One word: POStenzas.

They are not awe-inspiring. More like fear-instilling. Do away with them, and revel in the wonder of the tCs relatively neutral handling, even in stock kit.

BreakTheStatic

See what's weird though is when I first got the car I never noticed the instability at all, I don't wanna throw down a few hundred bucks on new tires if the problem is still there... I know the tires aren't good, but could they really be causing the car to oversteer like crazy?

Rick_NSX

I can promise it is the tires... my car has yokohamas on it and it handles like it is on rails at any speed the car is capable of

solorider

Don't be too quick to rule out alignment. With enough castor, excessive toe out will not cause the car to pull side to side. I'm not sure what the tC's castor angle is but a little too much toe out will make a car very twitchy at higher speeds.

My car is rock solid by the way.

Batjew

more insentive to get those pirellis :D

Bgnome

maybe it's the oversteer? i have seen several threads about tCs flipping off the highway..

lo_bux_racer

Why not start with the most basic problem of all? When did you last check your air pressure while the car was cold? If you are low on air pressure none of the rest of the stuff matters a whit. Any tire on any suspension will behave very badly if it doesn't have sufficient air pressure.

Limey

I doubt it's the 'POStenzas' although I plan on getting rid of mine ASAP.

i was just thinking the other day whilst on cruise control at 85mph how nice the TC handles at mid-high speeds.

It was a very relaxing drive down to Philly (apart from 192 where you have to drive at 60 or get a ticket.

DynomyteSW

i have logged to 400 mile trips in my TC no problems but i also do have the 18's w/ the perellis... really doubt its oversteer whilst going in a straight line

sensay

i used to think my car was unstable too... but that was before H&R and Koni came along...

BreakTheStatic

Nah its not the tire pressure, to describe it best, it feels like a slight movement in the steering wheel results in exaggerrated movement in the actual direction of the car. i never noticed this until a few weeks ago, like lets say the road has maybe a 15 degree curve to it, normally keeping the wheel steady at a slight angle would keep the car travelling along the little curve. However now it seems like i constantly have to correct the angle because the car wants to veer too much in either direction when i turn the wheel ever so slightly.

lo_bux_racer

There have been some reports of sidewall failure in the RE92. This might be an indication. Then again, it might just be incorrect toe.

tc913

iTrader: (2)

yea I know what ur talking about Break...I feel it too when I'm going about 70-80 and it's like the car makes these weird movements side to side and it's kinda annoying. I also took my hands off the steering wheel and it didn't jerk at all when I had my hand on it.

Beantowntc

its the re92

Eazy_Goer

I have an '06 with Yokohamas on it, and do not notice any issues at high speeds. About a month ago I had the little mule up to 120mph with no problem. (Mostly straight line and lane changing on a long stretch of highway). Okay, that was a one time deal, but I drive 65-70mph to work nearly every day with no noticable problems. I've had five other Toyota's and three of those were Celica's. I think the tC handles a lot like my '92 Celica, and I love it. The only handling problem that I've noticed is when you corner and simultaneously accelerate at lower speeds. Under these circumstances, the tC tends to "hop" a little, causing you to lose traction.

I agree with the posts about air-pressure. Typically, front-wheel-drive cars will tend to understeer. (Which is normally NOT a desirable trait - most of us prefer oversteer, making it easier to "drift"). I have my front tires about 3-4 psi harder than the rears, this helps to reduce understeer. In your case, you may want to have higher pressure in the rear, if your are REALLY experiencing oversteer. There was an excellent article called "Making it Stick" in Sport Compact Car about three months ago. If you can't find it on the net, I can scan and email it to whoever wants it.

One last thought... are you running any aftermarket body kits? I have the standard Scion ground effects installed. I've heard varying arguments that a) gorund effects are for looks only, b) they help you aerodynamically, and c) they can hurt you aerodynamically. My only point is that when you install a 3rd party mod that actually changes the aerodynamics of your vehicle - you really DON'T know what you're going to get. (Okay, I am making the leap of faith that Scion/Toyota actually wind-tunnel tested their goods - or at least ran a computer simulation). Even at 70mph, your pushing a lot of air out of your way really fast. A modifed body may be lifting your front-end ever so slightly and causing the squirly steering.

EZ~G

RollTide

I've tracked the tC on stock tires. The car will handle on those tires when properly inflated at higher speed(95+). The car does get really unstable under high speed moderate braking. When I say unstable, I don't mean a predictable movement like the back end coming out or sliding... it just gets really wiggly, the backend kinda jacks around from side to side. There's no steering wheel inputs going on when this happens either. It scared the crap out of my instructor and me the first few times it happened. I've had a discussion with a guy on this forum who has tracked his tC on the same track with DIFFERENT tires and noticed the same problem. It's not the track either. We decided it must be a suspension issue.

Could it be related to this some how?

-Tide

goingcarcrazy

I've noticed the back trying to seperate itself from the car under moderate-heavy braking. If anyone knows what this is, please by all means enlighten us! I ahve Potenzas for the record, and in response to the first post, I haven't noticed any increase in sensitivity. My Saturn used to become really light up front and basically not respond at all at around 55 and up, but the tC seems to stay planted pretty well. Plus steering sensitivity to me isn't really a bad thing at all, if anything at higher speeds it would be an advantage. And a random quesiton to put out there, does the tC have a variable ratio power steering system? If so that may be the answer to the problem.

Rick_NSX

I noticed (really noticed) last night that it has some issues in Heavy braking like the back end doesn't want to slow down. I saw an accident in front of me and had no where to go left or right so I laid on the brakes and it stopped very effectively but I had to make several adjustments to keep the back end planted... and I do not believe (don't flame me if I'm wrong) the tC has variable ratio power steering

emiller

Ive got the Potenzas too and never had a problem like that. Low air pressure or uneven pressures can make the car handle weird though.
Those Saturns can get scary like that. High speed going over a large bump and you can do whatever you want to the wheel and it wont respond at all for a second. At least my SC1 did that. Not fun in the snow.