Tamago's guide to ultimate yaris handling

[cleong]

We can't be certain of that fact which is why I stated the bar was available but can't speak for its effects. If it would make the car understeer worse like you say it would, then if you took the front anti roll bar off, would it cure the understeer without having to fit a rear anti roll bar?

I think it is possible that a correct front anti roll bar would reduce front roll, and optimize the tire contact patch in the corners, because too much roll unloads the inside tires. I'm not saying the Cusco would do it, because I've never tried it, but it is a tuning option that should be tried before being written off.

[Loren]

Originally Posted by cleong

We can't be certain of that fact which is why I stated the bar was available but can't speak for its effects. If it would make the car understeer worse like you say it would, then if you took the front anti roll bar off, would it cure the understeer without having to fit a rear anti roll bar?

Yes, we can be certain that fitting a stiffer front swaybar (with no other changes) will make the car understeer more. That's just simple suspension physics at work. That's just the way it is.

And, yes, removing the front swaybar would probably make the car understeer less (it's been done on some FWD cars with success), but while it might have higher cornering limits, the steering would feel very "sloppy" and it wouldn't be enjoyable to drive. One absolute truth about suspension tuning: It's always a compromise.

I think it is possible that a correct front anti roll bar would reduce front roll, and optimize the tire contact patch in the corners, because too much roll unloads the inside tires.

Body roll is not the "evil" that so many people think it is. Look at some of the best handling cars in the world... a Lotus Elise, for example... lots of body roll. Even purpose built race cars have some body roll in as much as their suspension moves. (look at an F1 car full-on in a corner, the outside is compressed visibly more than the outside) Body roll isn't bad. It's a by-product of weight transfer. What you want is control of that roll (good damping), and balance of the weight transfer (spring rates and sway bar rates).

If eliminating all body roll was the answer, every race car and high-end performance car would have NO body roll. Eliminating more body roll (with a larger front swaybar) at the expense of moving the handling balance of the car further in the wrong direction is no solution.

This whole discussion is much like arguing about lowering springs with ricers. They think that "lower is better" no matter what... and "stiffer and flatter" is better no matter what. It's simply not true.

I'm not saying the Cusco would do it, because I've never tried it, but it is a tuning option that should be tried before being written off.

I've not tried it on a Yaris, but most of my suspension tuning knowledge does come from experience. One of the first suspension mods I did to my Saturn when I started autocrossing was to put a bigger front swaybar on it. Same reason everyone else wants to: to get rid of the body roll. I then spent the next 3 years finding ways to eliminate the understeer that it caused. I was stubborn and refused to remove the front bar that I'd spent good money on, which would have solved the problem instantly. (as a side note, the Saturn S-Series cars had two swaybar options, the twin cam front bar was larger than the single cam bar... and the twin cam had a rear bar whereas the single cam had none... the hot ticket is simply putting the smaller front bar onto a twin cam car!) To balance the larger front bar, I ended up having to put a rear bar on that was so stiff that it actually BENT the stock rear end link mounts.

Wanna play with what removing the front swaybar would do? It's easy, just remove an end link on one side. The other side will hold the bar in place and keep it from flopping around, but with one side disconnected, the bar will have no effect. Very simple experiment. Somebody do it and report back. (maybe I'll do it when I have time)

If you have a stiff coilover suspension, you might get away without the front swaybar. I tuned the suspension on my old Miata with really stiff springs and NO swaybars. People thought I was nuts, but I wanted to prove that it could be done. It took really stiff front springs to get it to feel right, of course.