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Discussion Starter · #1 ·
I know one of the favorite mods people do to the IS300 is add sway bars, which made me curious.

Why did Lexus make this car with excessive body roll? There must of been some logic that they had for doing this. They couldnt of made this car with a lot of body roll just because there must of been some reasoning to this. So, what is it?
 

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Lexus had to design the car with comfort and luxury in mind, it wasn't an all out sports car.
 

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Discussion Starter · #3 ·
Correct me if I am wrong but adding some thicker sway bars wouldnt of hurt the comfort and ride quality of the car while reducing the body roll, right?
 

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sway bars do have some affect on overall ride quality, and part of the function is also shocks and springs that are not particularly stiff.
 

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Yeah... Toyota had to "refine" the Altezza for us here buying it as a Lexus. So they put a bunch of things on the car to dampen and soften the various characteristics of the car. To be honest... a lot of the mods here are just un-doing the things that Toyota did to try and make the car seem more refined.

Just to put things in perspective... my parents thought my IS300's stock ride quality was already a bit on the stiff side. So keep that in mind... the intended buyers for the IS300 was not teenagers.
 

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Correct me if I am wrong but adding some thicker sway bars wouldnt of hurt the comfort and ride quality of the car while reducing the body roll, right?
Sways bars do have some effect on ride quality since it causes forces on one wheel to be transferred over to the opposite wheel... but its effects on ride quality are nowhere near as much as if you were to put overly stiff springs/dampers on the car.

The reason I initially went for sways only was because I was happy with the ride quality and only wanted to decrease body roll.
 

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Also you get too stiff of a sway relative to the shock dampening and spring stiffness and you will end up with a car that is a bit unpredictable on the edge. You do not want your car to oversteer suddenly and out of control when you pass the limits of the tires all the time now do you?

Its a fine line of shock dampening, spring stiffness, and swaybar stiffness when incorporating it into a set suspension. As you know they would not redesign the suspension pickup points for the IS300 from the altezza by any considerable amount if any at all, that would be a bit too costly. A particular chassis will have all the arms and suspension components usually right in the same places.
 

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kponti... you actually made a good point. Stiffer sway bars decrease body roll... but the downside is that when you lose control it happens more suddenly.

Also varying differences between front and rear sway bar stiffness also affects the oversteer/understeer tendencies of the car.

It's not as simple as... I want to eliminate body roll so I'll put rigid sway bars. Everything you do affects something else.
 

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kponti... you actually made a good point. Stiffer sway bars decrease body roll... but the downside is that when you lose control it happens more suddenly.

Also varying differences between front and rear sway bar stiffness also affects the oversteer/understeer tendencies of the car.

It's not as simple as... I want to eliminate body roll so I'll put rigid sway bars. Everything you do affects something else.
Like life? aint life a bitch, lol
 

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Discussion Starter · #10 ·
kponti... you actually made a good point. Stiffer sway bars decrease body roll... but the downside is that when you lose control it happens more suddenly.
That is my concern. I had an 01 completely stock EXCEPT it had hotchkis sway bars. It made the car A LOT more planted to the road and made it go around turns with no body roll to speak of but also a false sense of security which ended with me wraping my car around a tree.

I now have a 2004 and I do not speed in the car, I do not take corners fast. I do however miss the car with no body roll. But I am afraid if I put sway bars on then I will turn back to speeding and going around corners with a false sense of security. If I put on L-tuned sway bars will it reduce the excessive body roll without giving me that false sense of security that the very stiff hotchkis gave me?
 

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If your goal is to reduce body roll but not wrap yourself around a tree, then you will have to bite the bullet and go with stiffer springs and shocks.

This is the best way to do it. Sways should be used to fine tune balance and in fact only the front is the one that truly needs upgrading.

I have the prokits and illuminas (setting 5 front/4 rear) with my L-tuned rear sway set at the mildest. For example, I corner flatter with far more grip and predictability this way compared to when I had my rear sway set stiffest with stock spring/shock or the sway set to the middle with the prokits/stock shocks.

I have stock rims with Nitto Neogens that have very decent grip btw.
 
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stiffer springs will help reduce body roll, as they will take more tension on the outside spring as you corner, and i think this would probably make the biggest difference. Also, if they are lowered springs, there is effectively 'less' distance to roll as the centre of gravity is lower. Lowering the centre of gravity will result in less roll, but also will allow more tension before the roll even without changing the spring rates.

Sway bars definitely make a difference, and my advice is to go only with a rear on the IS, but that is just me - i much prefer oversteer weather it be power assisted or not - as opposed to understeer. Keeping in mind oversteer is much more easily (read: only able) to be controlled with an LSD, preferably not the standard torsen type. Although the standard torsen LSD is good, once one wheel leaves the ground in really really tight cornering, the diff becomes open, soon as the wheel then touches the ground again, the LSD locks and then the car becomes a massive handful to bring back onto course.

Summary: Coilovers / Springs FTW with at least 10/8kg f/r spring rates + shocks to match if not coilovers, and swaybars + new swaybar bushes and 1-way LSD (1.5 way for big power cars and more advanced drivers) will completely transform your car. Oh, and GET AN ALIGNMENT. :D
 
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