Is highway wander caused by caster?

[Loren]

Swaybar will fix you up, Chew.

[chew246214]

thats what I'm hoping for just have to get off my backside and order it......

[Goose]

I have also been experiencing this exact problem for some time. My '09 Yaris' highway behavior is unacceptable.

I want people to know that if your Yaris tramlines or needs "more attention than it should" to keep going straight on the highway -- you're not alone. My Yaris will be going in for its third alignment to try to correct highway wandering.

I'm going to look over the tech's shoulder and have the car toe'd-in to the maximum within the factory spec range. They didn't do this the last time, even though I requested it. It sucks that caster can't be adjusted, since I also think this is the culprit. Before anyone suggests it, I'm not going to add a rear sway bar, since I think such a mod should not be needed to achieve decent highway behavior.

This is my third Yaris liftback. The others didn't have this problem. I haven't hit any potholes/etc to throw off the car's alignment. Tires are inflated to spec and I've ensured that the lugnuts are tightened to spec as well.

I'll let you know if more toe-in solves the problem (or a least makes this situation tolerable). Does anybody know if something changed with the liftback's suspension/steering between '08 and '09?

[Loren]

I haven't heard of any US spec Yaris suspension changes from 2007 on.

A little toe-in could help. I've definitely found the car to feel "twitchy" with toe out or even neutral toe.

[yaris2010RS]

wow, i am so glad this thread got bumped. when i posted my first comment my car was still very very new.

Originally Posted by yaris2010RS

funny.... i drive highway all the time with no hands on the steering (busy eating, texting, coffee, playing, adjusting....u get the point) and my only complaints are coming out of a turn or sometihng of the sort finding center is a bit of a job (steering does have a little bit of play or dead zone) but once the wheels are happy and true they stay like that....

quick thought (please dont let this offend anyone) check ure tire pressure.... u will be surprised how much 3psi difference will make. make sure all tires are the same, not jsut in range....

now that it has been more broken in, it truly is a pain in the ass on the highway. i do plan some time eventually to lower it a bit and put a sway bar kit on it so the wind wont push me accross 2 lanes anymore.

i jsut wanted to post and say i find it weird that my car didn't do this before but its progressing now.

[Goose]

Okay - after some negotiation I had my dealer set the fronts to 1/16" (or 0.15 degrees) IN. The service advisor told me that, if anything, I should set the toe OUT! I didn't try to educate the guy, but insisted that we set up the toe IN per my request. I'm taking a five-hour highway trip tomorrow, so I'll be sure to report back with my experience.

How much does rear wheel alignment influence how the car steers/tracks? I ask this question based on the following information:

The alignment was a four-wheel job, and the passenger-side rear is relatively messed up -- and it was not corrected. Both camber and toe are (relatively speaking) much greater than the other three; toe-in is .2 degrees in (double the others). Camber in the rear is interesting also; -0.2 degrees on the left, while it's -1.1 degrees on the right. Again, the relative difference appears pretty large; 1.1 is over five times as much, right?

Considering how the car is behaving, this is getting a bit old for me. I'm just sharing my (anal retentive) experience for your information.

Those that are knowledgeable about suspension setup/alignment are encouraged to share their thoughts.

EDIT: After reviewing the factory specs, I guess I'm just being too tightly wound. The specs are so relaxed that even these seemingly wide variances are within factory tolerance. It still looks pretty sloppy to me, though - why have specs out to two decimals if they're not really important?

Sorry... just being an engineer.

[Goose]

I'm still sorting things out, but I wanted to bump this thread in case anyone was curious...

Setting the toe slightly IN 1/16" has indeed helped the straight-line tracking on my Yaris. Thanks to those that have provided feedback with their experiences.

If you take your car in for alignment, don't let the shop get away with a sloppy job - the specs are there for a reason.

I still agree with the OP that caster is a big factor here. Although my car tracks better, the steering response still has room for improvement. My hope is that there's a little play in the top shock mounting point; if the top of the shock can be tweaked slightly rearward, steering feel should be more acceptable.

Although I posted this question elsewhere, has anyone noticed any "adjustability" at the top mounting point when re-installing the front shocks?

[Snubba]

Goose, I'm going to try the toe in. For a while I was focusing on the top shock mount and how to move it back. Maybe someday somebody will make an adjustable plate.

Somebody at an autocross said you could also move the lower control arm forward. I assume you could press the LCA's 2 bushings toward the back of the car, then the LCA would sit more forward. But there's not much room for that. I don't know how much movement it would take to get a good caster. And I don't know how much clearance you need when steering while going over bumps. But that looked promising. But before I go that far, I'll try the toe in. Too many projects at home that are more important though...


PS. The rear sway bar really makes the thing handle like a sports car! I recommend getting it even if it doesn't help the wander that much. On the highway going 70 around a slight corner, the car is much flatter and feels much safer. Around tight corners, it is another animal and sticks to the ground. Around town its more pleasant to zip around. It changes the character of the car for the better. If you enjoy a car's character, you would like this improvement. I went to an auto cross that a Corvette club was hosting and I did pretty well with my stock wheels and the TRD sway bar. At the lunch break I heard one Corvette guy say, "Lets eat some Yaris!" They were so surprised my 1.5L, 4 door, 36mpg, automatic, hatchback was getting good times. It was fun.

[Goose]

I installed a different set of tires today (195/60R15 Bridgestone HP550's) to see if this would help the wandering situation.

Based on the first few miles with the new tires, I'd say the change sucks. Tracking may have improved very slightly, but other aspects of the car's handling simply suck.

Things may improve as the new tires break-in, but I'm not optimistic.

[127.0.0.1]

Originally Posted by Goose

I installed a different set of tires today (195/60R15 Bridgestone HP550's) to see if this would help the wandering situation.

Based on the first few miles with the new tires, I'd say the change sucks. Tracking may have improved very slightly, but other aspects of the car's handling simply suck.

Things may improve as the new tires break-in, but I'm not optimistic.

do you have a rear swaybar installed yet ?

if not, get one.

[ddongbap]

Add 3 fat chicks. Wander gone.

[Goose]

Even if they're fat, my wife wouldn't want me hauling around three chicks all the time.

No swaybar for me. I'm going to try these Bridgestones for a but longer; if they don't improve, I'll exchange 'em for something else (30 day trial period).

[127.0.0.1]

sway bar will make far more difference than a tire ever will, and is cheap as 1 good tire

[yaris2010RS]

Originally Posted by ddongbap

Add 3 fat chicks. Wander gone.

fixes the height issue too

[cali yaris]

Add 3 fat chicks. Wander gone.

I'm not going to ask why he knows that.

but yeah.. SWAY BAR

[MUSKOKA800]

Goose asked;
"Although I posted this question elsewhere, has anyone noticed any "adjustability" at the top mounting point when re-installing the front shocks?"

My sedan has zero available adjustment where the upper strut mounts to the inner fender/firewall.
A second inspection would be helpful to confirm but perhaps a daring/desperate soul could hog out the mounting hole and then install a spacer/shim to keep the strut shafts top mounting point fixed rearward thus changing camber. Better yet, engineer a kit and sell it to the rest of us.

[Goose]

Well said, Muskoka. Since I enjoy gathering opinions, I stopped into my local dealer with this very idea some time ago.

The result of my discussion with a senior tech was that hogging out the mount would be the way to go (as you have correctly suggested). There was some head-scratching about the best way to secure the new mounting point to prevent misalignment - unfortunately, the upper strut mount isn't very robust.

I may go this route, although I'm still deciding if want start tearing into my car's unibody.

[turbomatic]

Would having heavier wider rims and tires help with the wondering?