Nixcision

iTrader: (3)

Again, it depends on your car, but im planning to drop 2.5 inches and im skipping out on Toe stuff for now......
Camber kits are always a good idea!! It isnt adjustable (unlike toe) AND if you decide to adjust your height or lower further in the future,then you can!!
Remember the whole purpose of coils, camber kits is flexibility with safety and economy in mind... one might think "wow thats a lot of parts" but the fact of the matter is: you wont need to buy many sets of tires cus you wore them all out (bad camber), you wont have bad shocks from cheaping out on springs, and you have the flexibility to afjust stiffness and height whenever you want (to an extent).
Im going with BC coils 14k front / 10k rear.
Ppl choose the 10k/ 8k and say its too soft. CMS recommends 12k/10k, but I was advised that our AWD weighs 200lbs more in the front... so 14k / 10k... this way if you go over a bump your springs wont travel (as much) to the point of bottoming out. Also theres the additional adjustments of dampening you can make by turning a **** by preference.

I encourage you to contact Circuit MS or Figs, even just for research...

lee786

thanks again with the helpfull advice well i wont be slamming it so i wont need those kits or anything. whats 12k/10k?

valeoray

12k and 10k are the spring rates. The higher the value, the stiffer the spring.

Nixcision, would you know what spring rates would achieve the comfort like a C300? or can the BC's be adjusted to dampened enough to be as soft a ride as a C300. Thanks!

Nixcision

iTrader: (3)

Difficult to say! The stock spring rates on that car are one thing, but the way the car behaves on the road and feels and weighs would be very different than that of the Is250.... its not as simple as chamging the springs and shocks... theres a whole laundry list of other parts that make up the suspension!
It wont feel like another car exactly, but im sure you could get it close.
I was told that the dampening adjustments are like fine tuning - dont rely on this for your ride - choose an appropriate spring rate instead. im going with 14 k / 10 k cus of my extra AWD weight lol

FSportIS

iTrader: (13)

@valeoray OEM suspension gives you the best comfort, period. Also, like Nixcision said, suspension is a whole system, there are a bunch of components working together to achieve the comfort and handling performance. Spring rate is only one factor of the many factors. Lexus OEM suspension is by far the most comfortable compared to many aftermarket suspension. Soft and comfortable suspension however, again in general, suffer handling performance to some extend.

Lower spring, coilovers are used more for purpose to lower ride height and increase handling performance. That usually involves higher spring rates and stiffer dampening so comfort will suffer to some extend. Do not do this if you look for better comfort.

OEM spring rates
5.4kg/mm front
5.6kg/mm rear

BCR standard spring rates, twice as stiffer than OEM.
12 kg/mm front
10 kg/mm rear

Other lower springs rates:
Swift Springs
4.6kg/mm front
5.2kg/mm rear

Tanabe NF
4.9kg/mm front
5.8kg/mm rear

RS-R Downs
4.48kg/mm front
6.0kg/mm rear

Tein H-Tech
6.0kg/mm front
6.3kg/mm rear

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
Credit to the spring rates source: https://www.clublexus.com/forums/sus...e-comfort.html

FSportIS

iTrader: (13)

If you drop 1inch-1.5inch max which is quite similar to most lower spring ride height like Eibach, H&R. You do not necessary need camber kit because your camber will be around -1.3 to -2.0 which is a bit outside of Lexus alignment spec. I lowered my car to 1.4 front, 1.0 rear with Eibach springs for many months and don't suffer any dramatic tire wear. In fact, some negative camber actually makes the car corner better. It is like the flat corner become banked corner in a way.

Toe kills the tire more than camber. Make sure you have toe at 0 or close to 0.

Lexus IS have this crazy toe changing during braking/cornering and that creates inner tire wear to all the IS, not just the lowered ones. The fix to that is the FIG #2 bushing (cost around $210 i think) to minimize the toe change during braking/cornering.

valeoray

So, I'm surprised the F-sports are softer than the OEM, yet they are lower.

lee786

thanks

lee786

its good to know that I wont need it thanks again

knguyenk

That's when the springs go over the normal every day bumps. This is why F-Sport springs are noted as similar to stock in terms of comfort, but if you max out the spring travel the final spring rates are as follows (which can be surprising, but not jarring or harsh):

Nixcision

iTrader: (3)

if you decide not to get camber kits thats fine. I, and many members who have been down this path, encourage you to buy coils!
Tire wear showing? Simple, adjust your ride height a bit (NOT possible with springs)
^lol this is kind of a "easy approach" but im just giving an example.