My Ultra Racing rear sway bar install

[regal]

A rear sway bar makes the rear push the car into under steer less, I think this is what the OP is trying to describe.

[justjesus]

Originally Posted by Loren

Read the thread I started about the 23mm bar, especially the first post. It has a pretty good explanation of how the rear bar works. It is admittedly counter-intuitive if you're not well-versed in the black art of suspension tuning.

I guess I got some reading to do!

[whoguy]

Hi all,

I must add to this discussion a little bit if I may.... With my Whiteline 22mm rear bar I have to be really careful in the rain as the car is prone to oversteer around sharp corners.... This is not a problem for me as I don't like taking corners in the rain especially if a power pole is right there.

For dry conditions it is excellent. What Loren says is on the money as always... I think a sway bar should be mandatory on a Yaris as it is very understeery from the factory.

[TitaniumBarbell]

Which bar must have more priority? Front Strut Bar or Rear Sway Bar?

[Sabretooth]

Rear first...the choice is yours of the TRD/Ultra Racing 19mm, or UR 23mm bar. I purchased the 19mm, and it seems just right for me, the case could be different to someone who has a different shock/spring/wheel/tire setup than mine.

The Yaris really doesnt even need a front sway bar, unless you have done every measure to make the car oversteer, or if the car naturally wants to oversteer (which shouldnt happen).

[schleppy]

Originally Posted by TitaniumBarbell

Which bar must have more priority? Front Strut Bar or Rear Sway Bar?

Rear sway, without a doubt. Some people (and I'm one of them) feel that a front strut bar doesn't do enough to justify the cost. The rear sway bar you will feel as soon as you turn the wheel.

[scape]

i'd also warn against any more weight up front! even if it's just a few pounds

[cali yaris]

^ The Yaris has a stock front sway bar. The aftermarket bar won't add much weight.

Further, most of the discussions about "oversteer" and "understeer" pertain to the limits of traction. Within those limits, the benefit of less roll is a valid handling improvement to make with the car.

There are two different conversations to have here -- how the car handles in normal to "spirited" driving (well within the limits of traction), and conditions when racing at the edge. Whether the tail or the head of car loses traction first is part of the second conversation, not the first.

[Loren]

There is a third aspect to consider. Even if you don't drive in a "spirited" fashion and never intentionally explore the limits of your car, how it will behave in an emergency situation is something that should not be overlooked.

To say that "it doesn't matter if the car oversteers or understeers because I never drive it that hard" is naive at best.

[CtrlAltDefeat]

Even without "spirited driving" it seems to make a lot of difference in everyday driving to me...

[TitaniumBarbell]

Originally Posted by Sabretooth

Rear first...the choice is yours of the TRD/Ultra Racing 19mm, or UR 23mm bar. I purchased the 19mm, and it seems just right for me, the case could be different to someone who has a different shock/spring/wheel/tire setup than mine.

The Yaris really doesnt even need a front sway bar, unless you have done every measure to make the car oversteer, or if the car naturally wants to oversteer (which shouldnt happen).

I ordered TRD Sway Bar Today with TRDSparks!

[Sandwash]

I've had my Yaris for only 2 weeks now and am considering getting rear sway bar. Very much appreciate reading of pro and con opinions although as can be expected am no less (or more) certain as to sway bar's net effectiveness. Question arises as to relative inexpense of sway bars, especially if produced in mass numbers, and why it is Toyota wouldn't include the sway bar as stock item if it in sum total better overall handling may be realized?

[cali yaris]

I can't tell if you mean the front or rear sway bar. I don't know of any cons to the REAR bar, but there is discussion on both sides for the FRONT bar. Toyota didn't include a rear bar to keep the cost of the car down, and based on their assessment of how most customers will drive (for economy).

Titanium, why did you pay more for TRD?

[Loren]

Originally Posted by Sandwash

I've had my Yaris for only 2 weeks now and am considering getting rear sway bar. Very much appreciate reading of pro and con opinions although as can be expected am no less (or more) certain as to sway bar's net effectiveness. Question arises as to relative inexpense of sway bars, especially if produced in mass numbers, and why it is Toyota wouldn't include the sway bar as stock item if it in sum total better overall handling may be realized?

Automotive design and engineering is all about compromises. The general public, especially the "commuter car" market, wants a car that is comfortable and handles predictably. Basically, they want an appliance. A couch that they can drive to work.

For these reasons, cars like the Yaris are designed with fairly soft suspension that handles most road conditions "comfortably" and the car is designed to handle predictably and safely. Predictable and safe handling for the average idiot driver means understeer.

Enter the rear swaybar. A rear swaybar's purpose is to increase rear roll stiffness. Increasing rear roll stiffness has a lot of effects, but the most obvious is a reduction in body roll and an improvement in steering response, which the "performance-minded" driver likes... but the general public might actually prefer the car to be less "twitchy" and prefer a little body roll that allows the suspension to lean in a turn instead of making THEM lean in a turn.

Increasing rear roll stiffness also changes the handling bias of the car and makes it less prone to understeer, or more prone to oversteer. The stiffer the rear of the car is made, the more likely it is to oversteer in an emergency maneuver. Toyota doesn't want the liability of putting the average idiot in a car that could oversteer unexpectedly, so they design their cars to understeer predictably.

Now, if Toyota wanted the rear roll stiffness to be greater on the Yaris... they wouldn't have fit a swaybar to it, anyway. It adds weight, complexity and expense, things that are considered greatly in the design of such a car. Even if they used the TRD/Ultra Racing design (a beam axle reinforcement rather than a true anti-sway bar), it would still add at least 7 parts to the car, one of them being a bar that requires complex forming and welding and heat-treating, the others being a pair of bolts, nuts and washers. (if they put a REAL swaybar on the car, the part count would be at least 3 times as many with brackets, end links, bushings, etc.) No, if Toyota wanted to add more stiffness to the back of the Yaris, they would simply have designed a stiffer beam axle assembly that allowed less twist or they would have fitted stiffer rear springs... either of which would create a compromise to the level of comfort that the car was designed for.

Um... what was the question again?

[Sandwash]

Thanks for your thorough and thoughtful response. You're right, most people want that couch they can drive to work so Toyota would not be so compelled; and, thinking about it you're correct - there would be other engineered approaches a manufacturer would take.
And, do you have a rear sway bar and would you hesitate in recommending one for whatever reason? Again, thanks--

[Loren]

This has all been covered before, but if you feel the need to tame some of the body roll and understeer of the Yaris, and improve steering response a bit, I would absolutely recommend adding a rear swaybar. My only caveat would be (maybe) to avoid going with a really large "competition-grade" bar if you're not a serious performance-minded driver with appropriate skills. Read my thread on the 23mm bar for more info.

[Twizzstyle]

I just installed a 23mm Ultra Racing bar, and although the install was a piece of cake, didn't remove the wheels or anything, my only beef with the bar is the bolts that it came with were too large for the holes on the suspension beam. The only way they would fit is if I drilled the holes out, which would be near impossible without taking off the whole rear brake assembly.

Luckily I've got a huge random assortment of nuts/bolts and found some bolts that fit perfectly. Not sure if the wrong bolts were sent with my bar or what, but they were not even close to fitting.

First impression of the bar is great, car is much flatter, but unfortunately the stock tires are so damn soft they just squish around. I'll be running the Yaris at autox next weekend (normally I race a 350hp subaru, but it has a fuel leak so I'm bringing out the Yaris for the first time) so I'll see how it does there.

[regal]

My impression of the TRD rear sway bar is that it doesn't help enough, the car still has pretty severe understeer even with the TRD springs. We really need stiffer rear springs and adjustable shocks.