albertgoq

Some Help

Had it for 2 weeks already installed, in my taste its still kinda stiff not the stock ride I had, maybe out of 100% stock feel it was reduced to 75%, I trimmed the front bump stops since shocks are shorter to allow more suspension travel. It improved the ride I bit but still stiff. What can I do before replacing them. Wait a little while to allow the shocks and springs to "Settle" "beak-in" if there is there such a thing?or cut the rear bump stops to 1/4

Spring rates are near as stock and up to 7kg at final rate but it seems still firm, and near other lowering spring rates

F-Sport Springs
Front = 6.6kg/mm
Rear = 7.0kg/mm

If I change the springs whats the best in terms of comfortable ride and stock feel, even if it reduces cornering performance.

Many Thanks

knguyenk

I'd say give it more time to allow you to get adjusted to the springs. Going on spring rates alone, if you don't like the stiffness of the F-Sport springs, then the 10k/8k spring rates of BC Racing coilovers (I think these rates are common for most other coils on the market: Megan, Tein, etc.) will probably be too stiff for you even with adjusting the dampening. I did a little digging and found a person that went from F-Sport springs to BC Racing and they seemed to like it. However, I found that there was not a lot of replies (if any). YMMV.

https://www.clublexus.com/forums/sus...coilovers.html

I'm planning on getting BC Racing coilovers with Swift Springs upgrade which is 12k/10k rates for my AWD IS and only plan on lowering down 1" like the F-Sport to avoid the issues of lowering an AWD IS. Otherwise, if I'm too lazy and rather set-it-and-forget-it I'm going F-Sport springs and shocks.

If that doesn't work, the easiest thing to do to go back to stock and retain all the stock comfort.

albertgoq

thanks!

install was great no squeaks or clunks its just the firmness of the ride, Is it the progressive nature of the springs? Because at good roads with a few dips and waves the ride is GREAT but at paved cemented roads its REALLY STIFF.

Thats why I'm thinking of

H-Tech
F - 6 kg/mm
R - 6.3/kgmm
or
Swift Springs which has the closest to stock
F - 4.6kg/mm
R - 5.2kg/mm

Or go the Coil-over Route with Tein Comfort Sport

Or the F-sport shocks are making the ride stiff together with the F-Sport Spring because it is a more performance oriented setup?

reyoasian

iTrader: (2)

there's also Road Magnets with are linear as well with a much better drop of 2" all around.
I'm running these with F-Sport shocks now, and it's more comfy compared to my old H&R sport springs with stock shocks.

knguyenk

It's more of the performance oriented setup; the compromise when one plays with performance (performance over comfort) unless you go for a dedicated performance luxury car.

The F-Sport springs are progressive springs, so they get stiffer as they compress. That is the primary reason why people note a bit of floating when they go over expansion bumps on highway bridges, as well as a stiff ride on harsh dips and bumps.

All lowering springs are essentially progressive springs to prevent bottoming out and retain comfort when not pushed in the corners, depending on their spring rates. Swift Springs are the exception, as they are the only aftermarket springs that are closest to linear springs as it gets. Swifts are often mistaken as linear springs due to how well they behave while being comfortable.

albertgoq

thanks for the inputs

what if i replaced the f-sport shocks to the tokico stocks with the f-sport springs (since f-sports are eibach 350's) will this be the more "COMFORTABLE RIDE" route because the f-sport shocks are slightly stiff also?

knguyenk

That would help improve the ride by softening the dampening, but wouldn't reduce the stiffness of the spring. It would make the car ride more comfortable than the F-Sport shocks.

FSportIS

iTrader: (13)

I have Eibach springs with stock shocks on IS250 and F Sport springs/shocks combo on IS350.

Both feels very much the same in term of comfort and handling. I just went autocross yesterday with IS350 and the F Sport springs/shocks/sway bar actually handles very nicely when I push it to the limit. Oversteering a little is very fun

FSportIS

iTrader: (13)

agree on this.

To OP, if you look for comfort only, stock is best.

lower spring or coil all inherently have stiffer springs. Coil especially have even stiffer spring rates than lower spring so the inherent stiffness cannot be fixed while dampening setting from the shocks can soften up that to make you feel more comfortable but that does not make it less stiff because the springs stiffness stays constant.

In general, stiffness improve handling and reduce comfort. Comfort and good handling go in the opposite way. That is why companies make progressive lower springs because the lower spring has less stiff rate (close to stock) under normal load and the spring rate increases only when you push it to the limit like hard and fast cornering. People complain about progressive springs because it is hard for the shocks to absorb since the springs acts differently (not-linear so sometimes soft and sometimes hard). However, to me, i personally like progressive springs especially from Eibach. I really like the comfortable feel on cruising (almost feel like stock to me) and improved handling in hard corner (way better than stock).

albertgoq

thanks for the insights, I replaced the shocks already to the tokico stocks and the f-sport springs (technically Eibach 350's) and much much improved ride comfort, gone are the performance that you would want in a sports sedan like less body roll on cornering, and tight in the sweeping curves, but it's all good from 100% stock springs and shocks its like 95% to 90% for springs only with tokico stock shocks, still stiff but has better dampening compared to the F-Sport (bilsteins) we side by side how the tokicos and bilsteins rebound if shocks where compressed without the spring. The bilsteins was really hard to compress

I don't drive hard its a daily commute, still stiff but a lot more comfortable to drive as there is more softer dampening on the shocks

now a happy camper

knguyenk

I'm glad that you found a solution that works for you.

The thing about modding the suspension of any vehicle is that it is a lot of trial and error; what some find comfortable with a particular setup maybe too harsh/stiff for another, or too high or too low, too unpredictable or too sharp, etc.. So it takes a bit of effort to find that balance/compromise that you want in the performance vs. comfort in modding.

You seem to have found it and enjoy the result that came from it.

albertgoq

Yes thanks! quite costly though, for the un-install and re-install together that I need to sell the f-sport shocks now

here is how it looks 2 fingers gap front and rear

FSportIS

iTrader: (13)

Congrats for figuring out what you want. This is it. You know what, I did go through the same route and end up like this:
1. IS250 with Eibach springs on stock shocks for daily driver exactly like what you did
2. IS350 with F Sport springs and Bilstein shocks for autocross/track usage

Could you let me know how much you sell your F Sport shocks in a PM form, I might buy and use it on my IS250 in the future. Thanks.

FSportIS

iTrader: (13)

My IS350 seems to be a bit lower than yours with F Sport springs. I have about 1 to may be 1.5 finger gap all around. The gap on the passenger side is bigger than the driver side (left). Does that happen to you too?

albertgoq

maybe it has not settled and I added rubber silencers for each dead coil, but as the mechanic said it will eventually settle as I use the car, yes there is a slight slight slight difference a little higher on the passenger side, maybe 1/16th of an inch. I'll PM you on the f-sport stuff : )