yellowssm

I called eibach 2 days ago and the rep said september or so...

jt4you

all sway bars do is reduce body roll. If you want to reduce under/oversteering, you have to analyze the weight of each tire as it turns. sway bars have no affect on the tire.

linnboi

eibach sounds aite, any other kinds ???

Ichigo

I actually just got a call from Tanabe Racing Development to use my car to make some measurements for strut bars. Unfortunately I was unable to meet up with them, but Im sure they got someone else to help them out. This of course leads me to believe that strut bars are being developed and will be available in due time.

al503

Sway bars do affect how the tires make contact with the tarmac, which affects under/oversteer.

Jay M

changing out suspension parts shouldn't be taken lightly. A proper suspension system is made up from a collection of parts designed to work in harmony.

Lexus designed this to to be a performance car so they have already compromised comfort for handling.

The question what else can be changed to improve street performance.

The street is MUCH different than a race track. A street is very bumpy, where most trracks are smooth. A very stiff suspension will handle lkke a dream on the track, but downright dangerous on the street.

Alignment can be optimised for street or track. Aggressive camber will trash the tires on the street, too little camber and the tires will be trashed on the track.

A strut brace will only stiffin the chasis. If the chasis is flexible that will adversely effect handling. If the chasis is already stiff enough, then a strut bar will do nothing but add weight.

Ther are two schools of thought on springs vs sway bars. 1) stiff spring with light sway bar, 2) light spring with stiff sway bars.

I don't know all the arguements for soft springs, but this is how stiff sway bars can really screw up handling:

If for instance you put a big thick sway bar in the rear, what will happen is when you make a fast turn the inside wheel will lift off the ground. Not completely, but it's contact patch gets very small.

Two bad things happen when that inside wheel lifts off the ground

- you now only have one tire firmly planted on the pavement, so your latteral stability is reduced.

-If you don't have traction control, this is where it gets VERY dangerous- the inside wheel will start to spin, and with posi-traction, it will also cause the outside wheel to spin! Before you know it you will be into the gaurd rail.

I don't know much about drift cars, but I suspect they have enormous sway bars.

In a nut shell, thick sway bars reduce the benefit of independant suspension.
But it comes down to proper design and carful balance.

You have to ask yourself who put more r&d into IS handling: Lexus or Eibach?

~Jay

jsquared

well i know very little about strut/sway bars. all i know is that it can/should improve handling and such. i was looking into getting some kind of bars when they were available but after reading all these post, i wonder whether it will just be a waste of money for me. i'm always up for improving the car, but how much of an improvement will it be and will it be worth the $$$? i'm more of a daily driver, with the occasional joyride, but have not hit the track yet. i do plan on going in the future, maybe after i get an exhaust + other things.

so all in all, my question is, is it really worth it for strut/sway bars?

linnboi

i'm pretty much lookin to reduce the body roll of the car. it handles good enough. i just wanna make it a bit better with strut bars and sway bars. so far i havent been able to find much for the car. hopefully someone has a lead for me.....hehe

lobuxracer

iTrader: (2)

Tower bars will not affect body roll. It would be impossible to put strut bars on the IS because it doesn't have struts. The biggest reason for strut bars is to maintain camber under load. This site gives a pretty good explanation of why a STB is a good thing for a car with struts. However, the IS has double wishbone suspension, not struts, so the advantage of stiffening the chassis this way is far less than a strut-type. It might be just extra weight. It certainly is on a Supra like mine with a hard top.

Stiffer springs will reduce body roll. So will stiffer anti-roll (sway) bars. For the street, you'll probably be better off with stiffer sway bars. Stiffer springs and their necessarily stiffer dampers will compromise ride quality, and if done to the extreme, you will have some heart stopping moments with braking over washboard surfaces because your wheel compliance is poor and the ABS is fighting your desire to stop with the wheels locking and unlocking rapidly.

It seems to be an even bigger problem with EBFD found on all the late model Toyotas. I can say I've had some scares in my tC (with Tein SS-Ps and twice the spring rate of the OEM springs) while trying to stop on poor surfaces. At the same time, the suspension changes completely transformed the car's performance on good surfaces.

BTW, I have a LOT of experience running negative camber on street driven cars in the -1.5 to -2.5 range, and I've never had wear problems. Inside edge wear is from incorrect toe, not excessive camber unless you are running more than -3.0 degrees, which would be a completely foolish setting for street driving. If the IS really does have 3mm toe-in at the rear, expect to see inside edge wear in a hurry. But alignment is another thread somewhere waiting to happen.

Lets Drive

iTrader: (3)

Where will you primarily be driving the car?

If its the street, then these guys have it right:

^^ Yep.

and,

Yep, same with my RX, being double wishbone type, as opposed to using the strut as the upper control arm. Strut tower bars only make a real difference on the track, but not much if any on the street given our type of tires (they lack the ability to produce the same cornering G's). While the bar doesn't add to handling ability, it is arguable if it contributes to feel, which would be the only reason (and actual reason for me at least), I'd have one on. If the chassis was flexing enough to warrant a strut bar on the street, to the point where it was noticeably effecting handling, the lack of one would have the car ripping itself apart...good thing they build the chassis from the factory to be rigid as is.

linnboi,
BTW, while body roll may seem bad, it doesn't always translate into handling, or lack thereof. If you want to reduce roll, then aim for your springs and shocks with a nicer damper level to keep driving on city streets more bearable. You'll sacrifice the 'feel' of a lexus, but if you bought the car for performance over luxury, so be it eh? Just don't go spending your money on anti-roll bars, looking for a big improvement in roll management, because you'll come away disappointed, and still see longitudinal forces at work when accelerating or braking hard.

al503

Y'all have to remember that going to stiffer anti-roll bars may help keep the car flatter, which may in turn give you more confidence. However, going too stiff may actually hurt the overall grip levels as you're decreasing the wheels and tires ability to act/react independently.

I use anti roll bars strictly for fine-tuning under/oversteer only usually using the softest of the stiffer settings (if they're adjustable). Roll control should be adjusted with springs as mentioned by several above.

ff_

Sure, if your only comparison is the Camry.

ddquach

iTrader: (3)

I believe LMS has some being done right now. I spoke with Steve and he said that it should be in some time this week or next. I try calling LMS and talk to Steve about it...

lobuxracer

iTrader: (2)

The whole thing is a big balancing act. Springs are great for roll control until you get so stiff from high spring rate and stiff damping to control those springs that you lose wheel compliance. Roll bars are great for keeping the car flat until the suspension starts acting like a live axle. Just like any engineered piece, you'll make compromises based on intended purpose and customer satisfaction.

All the ricky racers here would like the car to ride and handle like a Porsche or Ferrari. All the Grand Touring drivers would like it to feel like a BMW or Mercedes. All the Cadillac drivers would like the factory to make the ride absolutely plush. There's absolutely NO way to make all these groups happy, so the engineers pick a target market and aim to please that market. Out of this we got the IS350, a sporty sedan.

I like it just fine. It's better than the wife's '97 Camry, and it's better than either of my other cars for my intended purpose (taking clients to lunch/dinner) while not floating down the road with a completely disconnected feeling. But it is far from my weapon of choice for corner strafing.

Gernby

iTrader: (1)

That is not correct. Larger sway bars do reduce body roll, but if the ratio of stiffness changes from front to rear, under / over steer WILL change.

For example, if you put a larger sway bar on the front and a smaller sway bar on the rear, the lateral and vertical loads will be much more evenly distributed on the rear tires and much less evenly distributed on the front. In extreme cases, the inside front wheel may actually lift up off the ground. This will cause dramatic understeer. The opposite is also true, so a large rear bar and small front bar can cause the inside back wheel to lift off the ground causing significant oversteer.