sammy5001

Or is it just for looks?

If there's improvement, is it substantial?

lexboi250

iTrader: (10)

handling will definitly be improved, also looks 100x better. not sure about MPG though

Celsior400

iTrader: (1)

handling? yes MPG? no

substantial? depends on what set-up you go with... look for coilovers...

RTIS250

iTrader: (9)

There is definately a substantial improvement in handling.. anytime you lower the center of gravity, your handling will improve. Of course it will look a ton better. Any MPG gains would be extremely minimal, meaning fractions, and would be due to a lower coefficient of drag due to the car being lower.

PhilipMSPT

iTrader: (5)

Well, maybe not 100x...

I have Eibachs, and they definitely handle much more confindently with twisties, freeway on/off-ramps, and sudden lane changes.

Gas efficiency? I think driving style is more important than any performance or aesthetic modification on the car...

FiveOhNine

Any less 'floaty' at high speeds?

BlueSander

haha, that's exactly what I'm thinking of, too. I'm in the market for a used 250 AWD now and I haven't get some extra time to test drive yet. I put over 300mls on my friend's 07 GS350 AWD. The car is very fast, but at high speed the car just feel floaty compared to my solid Audi A4. Anyhow, that's the GS, i wonder how the IS will be

lobuxracer

iTrader: (2)

This is only true to a point. Once the roll center get too far from the center of gravity, then true handling suffers again. It is very possible to go too low on a stock suspension and have the car measurably worse.

The people I know who genuinely drive fast have their Supras at stock ride height because it works best on the track. They change their spring rates to add roll resistance and put bigger sway bars on the car, but the suspension geometry works best at stock ride height.

Because the IS is available with a "sport" suspension option, we know we can lower the front of the car 10mm without ill effect, but the rear ride height is the same regardless of sport or standard configuration. So, in all likelihood, dropping the car more than this will adversely affect handling.

And before all the guys who lowered their cars jump on this, you'll need a watch and a timed course to measure the improvement (or lack thereof) - it's not a seat of the pants difference.

Finally, Sport Compact Car actually (I'm not generally a big fan of magazine articles) did a great series on this awhile back where they discussed roll couple, roll axis, lowering, and what it really means. If you have questions about lowering it would be a great place to start. It is a multipart series with 6 parts in total. Read it all, and you'll know more about suspension tuning than most "tuners."

al503

It may not be true at all. Whether the stock springs were linear v. progressive and whether the replacement springs are the same or not will make a difference.

You'll have to reckon with the suspension geometries that will be altered. Sometimes its for the better, sometimes it's not.

How do the new spring rates work with the shock/strut valving (if you're not changing them out also)?

Are the new spring rates in proportion to the stock rates? In other words, is the new front spring rate 20% stiffer but the rear is only 10% stiffer? How is this going to change the car's understeer/oversteer tendencies? Under cornering loads/forces, the car will be compressing the springs different amounts. How will this affect the amount of camber each wheel/tires sees? As a result, will there be too much or not enough camber to keep the biggest possible contact patch with the ground?

The only thing you can say for sure is that the CG will be lower and that will benefit the handling in and of itself. Whether that benefit is enough to offset the detrimental effects, if any, is anyone's guess until you can get it out there and test it out.

FiveOhNine

I guess no one knows whether it corrects Lexus high speed 'stability' or lack thereof......

lobuxracer

iTrader: (2)

There is no lack of stability at speed in an IS350. Not even at 144 mph. I'm in an ES350 right now because my IS is getting a second new set of cam sprockets installed. It feels floaty. I'd bet a lot the GS feels very similar since the target markets for these two cars is not the sport crowd.

FiveOhNine

I guess it must just be mine.....

FiveOhNine

Yep, had it out on the highway today between 70-80mph and it felt like a moving truck in the wind. I just can't seem to keep the damn thing going straight at those speeds...it almost feels like my wheels are falling off.

I think I need to get the center of gravity lower....

GSteg

iTrader: (15)

if you're having tracking problems, then having a lower center of gravity isn't going to fix it.

Check your tire pressure and make sure your alignment is good. Having one side of the tire pressure a great dealer lower than the other can cause your car to pull to the side.

FiveOhNine

I've varied the pressure from about 30 up to about 42 and everything in between on two different sets of wheels and tires. I really wish it was that easy.

I've also had the alignment checked at least 3 times in the last 4 months.

I'm beginning to think I'm going crazy. I need to go find a used 2007 and do a test drive.

Edit: If this makes any sense: it almost feels like the car is 'rocking' side-to-side a bit. Maybe sway bars would help?