Spring question (don't laugh ...)
 

Okay, I see most people on here are installing springs to either lower the car or to firm up the ride.

I want to soften it. I have a new Premium/Nav IS350, and the jittery ride is annoying. I mean, it'll jiggle your titties even if you're a guy. :D

I've taken the cold tire pressure down to 30 and it helped a little, but the ride is still nervous and jiggly. I would like to find maybe some progressives that will absorb the little ripples but maintain reasonably flat body motion in the twisties. I know it can be done, since my Infiniti M45 handles this kind of thing perfectly.

So does anybody have any ideas where I could start? Never done it before.

TIA

wait for this and raise the height? not really sure

http://www.tein.com/cstdamp.html

do you have the sports package?

This is my first Lexus and I sort of assumed that it would be a very smooth riding car. If I had spent more time on the freeway test driving this car I may not have bought it.

In southern california the freeways are all bumpy concrete. My wife commented this morning that if she wanted a smoothie she would just have to eat the ingredients and the car would mix them in her stomach.

I haven't driven a GS, but a porter from the Lexus dealer picked me up and drove me to the dealer to pick up my IS. I think the GS is just as bad on the freeway. In fact I had doubts about my purchase on the way down there.

So I'm not laughing! I also would like more sensable springs and shocks.

Someone said in another thread that the IS was the roughest riding car he ever had and that his C5 Corvette was much smoother. I think that on the freeway my '68 Corvette might even be a bit smoother.

In every other way the IS is nearly perfect. I love that car around town, but I may need some dramamine if I go on a long road trip!

Maybe an airbag suspension would solve the problem.

I also considered switching to 17" rims, but I really like the look of the 18s and I'm not sure that the tires are the problem.

~Jay

No. Thank goodness I don't! :D

Yeah, it's just a fairly constant jiggling. I figure the intial spring rate is firm enough that little ripples in the pavement don't get absorbed, but rather transmitted to the car body (and its occupants).

I don't think the rebound rate on the shock portion is the problem, since it seems to be pretty controlled on the upstroke. A nice progressive setup - with intially softer rates to absorb the little road orregularities - then a firmer main coil to control roll and major bumps - would be ideal.

But I guess these are struts anyway, so you have to buy the spring and shock as a unit. Someone would have to design a combo that worked just for this purpose.

I've noticed the same. While the ride certainly isn't "punishing", it's jumpy enough for me to wonder why Lexus didn't consider a system with lux/firm/sport modes. Some of it certainly comes back to the 18" stock wheel/tire combo.

Sorry, you won't find a spring that is softer unless you order them custom made. (Likely ordering them in a coil over setup, but you can just order custom springs alone).

Even the NF210 springs from Tanabe increase the spring rate slightly. Any lowering spring will increase the spring rate to try and keep the wheels out of the wheel wells.

I know what you are saying about the jittery ride. I'm here in California and I have the same issue with my Lexus. My other ride is a Scion tC with H&R Coilovers, so by contrast the Lexus is a dream to drive. (tC is a very harsh ride - H&Rs for the tC have no adjustability except for the height.)

I guess it's all a matter of perception.

-Brian

all of the springs that i have seen, come with a higher spring rate. You might have more luck with coilovers. I read a review on the teins (for a gs) that stated a softer than stock ride.

Thanks guys. I'm not really looking to lower the car, so that isn't an issue. I just want to take the initial harshness out of the ride.

Right, the only way you are going to be able to do that is by replacing the springs. Excluding coilovers - all of the available suspension replacement options will lower your vehicle.

Lowering springs, will make the ride harsher, unless custom ordered.

Replacing the suspension with coilovers (which can be set to stock ride height), will generally make the ride harsher (Unless the coilovers are ordered with custom spring rates).

If you are ordering custom spring rate springs, you may as well contact Eibach directly and have them make you springs alone. This way you don't need to needlessly order a $1500 set of coilovers. (Custom springs only that are the stock ride height with a lower spring rate will be far cheaper than $1000-1500).

-Brian

I think most of the jittery ride comes from the rear springs. I notice when I have some weight in the trunk it rides much better.

Spring rates do have an effect on the 'choppy' or 'jittery' ride.

However, I think it's determined more by the shocks damping characteristic/setting. I would wait until Koni, Tokico, etc. comes out with an adjustable shock and look at your options then. Otherwise, you might look at the Tein CS coilovers if/when they make it for the IS.

Do you have the 18" wheels? If so, downgrading to the 17" wheels, which have a higher profile (45 rather than 40 aspect ratio) tires ought to help.

I agree with Al503 that lowering spring rate while still keeping the same shocks might lead to a *more* choopy ride, and might reduce your ride height (softer spring rate at the same spring length = more spring movement). Progressive springs might work, but right now AFAIK there's nothing out in the marketplace. The proper way for suspension tuning is to match your car's weight & handling characteristics with the proper spring rate and shocks for the right amount of suspension travel.

You're going to have to wait for more advanced coil-over/shock combo's for touring/GT use (I really doubt anyone is going to make this, so IMHO, its a waisted wait). Everything out there is for a more "sportier" ride.

Two thoughts:

1) Ask Lexus if alternative shocks and springs from say an ES might work on the IS. Its not really a far fetched idea since the IS's current springs and shocks were (I think) originally from the GS. The cars are all very close in weight, so that might work. Be aware that weight-distribution is different between these cars, so further analysis of equivalent weight-distribution should occur.

2) I recommend going even further to 16" rims (I know, that's a crappy option for looks) to something like a 225/55-16. I know this is probably blasphemy for those with 20" rims, but hey, it might work for you.

HTH - Ravi