Lvangundy

The more and more I modify and drive the GS430 the less I'm impressed with it's agility, or lack thereof. I've done most commercially available mods and have yet to appreciate their supposed benefits.

I'm going to start out by rulilng out the weight factor - there are other cars (Audi A6 2.7T) that weigh 200-400 lbs more than the GS and outhandle it. Now, there is the AWD factor, but, how baout the BMW 540i?

Take a step back and think about a car - 4 wheels - what is different about other 4 door sedans that allow them to cut corners and zip around? It's not weight.

If the car was designed and built for comfort - how was this done? Were the shocks mounted a certain way? Are the control arms angled a certain way? What is it?

Kharizma

iTrader: (6)

what kinds of mod's do you have done? my GS handles great.. i have the daizen sway bar bushings, tein CS, new built front suspension, cusco front strut tower bar... it handles great now..

TeeLex

iTrader: (24)

I have Tein CS/EDFC, Daizen sways, LTune steering ECU, Tom's front and rear LCB's , Tom's 6 piece links, DSR front STB and a Ugo rear STB with 20 X 9 and 20 X 10 rims, and I think my GS does pretty well in the handling department. Sure it's heavy, but my car is night and day different from a stock GS.

Lexbox

I noticed the strut bar from Carson has allowed me to take certain curves at much higher speeds. I cant wait til the Tein CS get here.

BA_GS400

iTrader: (1)

To more directly answer your question, for any car, the two largest factors would be the Springs and the Swaybar. I think that it's safe for us to assume that the 'basic' suspension design's are similar in the cars you mentioned. ie. Upper and Lower A-arms using either a McPherson strut type of design design of shock/spring in between. Nothing earthshaking. Probably 4 wheel independent suspension, aka, no single rear axle, each wheel and 'half-axle' operate independantly. Their basic designs are not that different from what I know of them.

Here's what sets them apart, and you are correct, it isn't about total vehicle weight.
Springs can obviously be on the soft side or very stiff (600lbs/in or higher is STIFF)
Springs can also be 'progressive'. This means that their spring rate increases the more it is compressed. This is usually accomplished by having the coils tighter, or closer together.
This tends to give a softer ride in a straight line, that stiffens up in a corner.
.
Swaybars can be thick, thin, hollow, solid, large diameter, small diameter, etc.
Stock wheel and tire choices also factor in. Obviously you will usually get better cornering by going to a shorter (stiffer) sidewall, as in a change from 40 series tires to 30 series tires.
Then there is also things like chassis structure or torsional stiffness, shock design, weight distribution, etc.

So, my point is that it isn't any one thing. It's ALL of those things (and probably a few I missed) and how they are made to work together.
Lexus just chooses to use parts for a softer ride. Softer spring rates, thinner swaybars, bigger sidewall tires, and a chassis that is not as stiff. (and usually a more power assisted steering effort as well)


The changes that the guys did above address all of those Lexus qualities, and move the bar towards a firmer ride at the expense of some "cushy/soft" ride qualities. Since the lexus' are so soft, we've got a lot of room to give some of that up, and aim for better cornering.


Lvangundy, I hope this helps some. There are some good websites that can go deeper into the whole thing of course. We can maybe find some links if you are interested in some deep reading.

Lvangundy

Thx for the input.

For the mod curious, here's what's on my car
Daizen sway-bars
TOMs FLCB
TRD Tower Bar
TOMs RLCB
TOMs 6-Link
TOMs Rear Tower Bar
TEIN CS (~ -1.75")

There's still a lot of body roll - I'm hoping the stiffest setting on the rear bar will help with this. It's currently in the middle position.

I haven't driven an M5, but I assume it handles well. Can this be achieved? Do the shock mounts need to be repositioned?

trbopooh

u probably need to change out your daizen sways to trd sways and the tein cs to flex.

JeffTsai

iTrader: (1)

Definately get some Tein Flex
Lower the car a bit, set the preload to a pretty stiff setting. Set the damper to the stiffest setting.

Switch to TRD Blue sway bars. Both front and back.

Get some 18's or 19's wheels with 35 profile or 30 profile tires. Tires also need to be of the ultra high performance or extreme performance variety. Also, have the tires set to 35-45psi.

This setup should make your car handle like it's on rails
Although you are going to sacrifice a bit of that cushy ride though

Lvangundy

The problem with setting the dampening to the max setting is that this creates massive understeer in the front. The car barely wants to steer in the determined direction. The dampening on the Tein CS seems to affect oversteer/understeer more than anything. I get the impression that this is the dampening is designed to do.

Right now I've found that a setting of 6 in the front and 8 in the rear creates a desireable ride.

It's been suggested to me by TM Engineering to upgrade the springs in replacement of the CS springs to something more 'stiff.' I'd like to talk to Todd about this more.

I know bushings are in order soon, and I'm not convinced about the TOM`s front lower brace yet. I think it adds to the understeer issue.

trbopooh

i have my tein cs set at 13 front and 12 rear. i found it to be less floaty (sp)??? did u try to play with the settings? my rear sway is set in the middle also. maybe u need to ride in another member's car? i did and it helped me decide on what i wanted.

cliffud

iTrader: (3)

keep in mind fellas that the Tein numbers are flipped if one of you is using EDFC...

16, 15, 14, 13, 12, 11, etc...

vs

1, 2, 3, 4, 5, 6, 7, 8, etc...

chuckb

I love my 430, but the GS is just not an agile car. it's too long, heavy and numb. sometimes it feels funner to whip my wife's caravan through the twisties than my GS with Tein CS and 18 inch wheels.

lexforlife

iTrader: (7)

bro

if you are after aggresive handling and i mean agressive , the teins cs will not do , its for more for comfort, you have great supporting mods like mine but you need to move to a setup like the teins flex so you can adjust spring preloads to give you the agility you desire or go with the jic or zeal coilovers which are designed for aggresive race type driving also make sure you have your sawys set on aggressive in the rear and make sure you up tire pressure front to 42lbs or so and rear at 40lbs

if you were in florida i would invite you to take a drive in my car , when i had the bilstein pss coils on i used to handle like a go cart and i do mean go cart with the flex i have more flex to adjust from somewhat comfort to all out race with me edfc


right now i can hang with any modded m series and the like without issues , i can almost drift the gs with ease

lexforlife

iTrader: (7)

bro always set the rear 2 clicks softer then the fronts , front handles weight of engine and is fiirst to establish turn in so you want it slightly firmer , rears establish ride comfort

lexforlife

iTrader: (7)

also folks you cannot and i repeat cannot have razor sharp handling even with these mods without swapping out your front bushings especially the lower control arm and castor arm ones , they are so mushy and soft and introduce way to much deflection to achieve world class handling

order th daizen urethene bushing kit and you will see a world of difference in handling and remember you cannot expect world class handling and have a strong desire for ride comfort , it is almost impossible to reach that median