nal831

iTrader: (1)

Hey guys, I have an*08*IS350*and I just installed the*F-sport*rear*sway*bar. Now I want to lower the car. I am set on the*eibach pro kit*but i am thinking about using the pro kit for the 250 because of the*lower drop. The only diff between the two sets is the initial spring rates of the front springs. (29 lbs)

Pro Kit*IS250*8288.140*Spring rates front 199-to-314
rear 217-to-354*
Lowering front 1.4" rear 1.0"

Pro Kit IS350 8287.140 Spring rates front 228-to-314
rear 217-to-354
Lowering front 1.0" rear .8"

Would you guys do it? And if you have done it already, what's the verdict? Good? bad?I'll be using stock shocks and I only drive around 10k miles a year.*Thanks for your guys' input!!

FSportIS

iTrader: (13)

I think either spring will work on both the IS250 and IS350. I haven't done it myself but I heard that they are compatible.
https://www.clublexus.com/forums/sus...-an-is350.html

I have the Eibach IS250 version on my IS250 and it handles better and feel firmer than stock. 1.4 front and 1.0 rear is also perfect lowering for my daily driver as I don't have problem driving in and out driveway.

nal831

iTrader: (1)

Ya, I have been doing some heavy research and it seems like the consensus is that the 250 pro kit will work on my 350. I just wanted to see if there were cons of doing so. I mean the curb weight difference between the 250 and 350 is only about 100lbs so I wouldnt think it would cause any major problems. Besides the obvious premature shock wear. I know a .4" difference in height for the front springs might not seem like much but I think the 250 drop looks way more clean than the 350. Thanks for your response.

FSportIS

iTrader: (13)

I think the premature shock wear is related to how stiff the spring is, not how low they are. In general though, the lower, the stiffer the spring rate and therefore, some might think that the lower the spring, the faster it kills the shock. However, it is the stiff spring rate that does is.

Since both Eibach versions spring rates are very similar, they should affect the shocks similarly.

albertgoq

The springs rates of the eibach 250/350 are much softer than the f-sport by eibach. Guess this is the reason why f-sport springs are stiffer/firmer compared to the eibach 250/350

FSportIS

iTrader: (13)

Oh no wonder there is a firmer feel on my IS350 lol. Do you know precisely their spring rates in term of kg/mm?

albertgoq

eibach rates

these rates are not bad for progressive springs

Pro Kit IS250
Spring rates
front 3.5kg/mm initial rate to 5.6kg/mm final rate
rear 3.8kg/mm initial rate to 6.3kg/mm final rate
Lowering front 1.4" rear 1.0"

Pro Kit IS350
Spring rates
front 4.0kg/mm initial rate to 5.6kg/mm final rate
rear 3.8kg/mm initial rate to 6.3kg/mm final rate
Lowering front 1.0" rear .8"


F-Sport are a lot stiffer and as you install the springs when the weight of your car sits on the springs the rates already increase

F-Sport by Eibach
4.7kg/mm initial rate front
4.0kg/mm initial rate rear

6.6kg/mm final rate front
7.0kg/mm final rate rear

Lexus should have stuck with the eibach 250/350 rates instead if redesigning the f-sport springs to the stiffer rates

Kd0t

iTrader: (17)

Is going lower your only concern? There are other brands that drop the 2IS lower than the eibachs.

I think h&r and road magnet are the lowest? Hopefully someone can chime in on this

FSportIS

iTrader: (13)

Do you mind sharing the source of where all these spring rates are coming from?

IS-SV

So we never got the source?

If it's true, then no wonder the FSports have measured improvement in handling.

FSportIS

iTrader: (13)

Yes, I still have FSport springs/shocks combo on my IS350 and I can confirm the handling improvement on both street and track.

IS-SV

Yes, I still run Eibach350's on my IS350 and handling improvement is only minor. But ride quality is surprisingly good.