nMeOnE

iTrader: (2)

I want to get a set of springs for my car and was wondering what the stock spring rate is on our cars.

Hopefully i can find something that would match it or if not i would just get some tein-cs and the spring rate same as stock, hopefully it will give me that lexus ride quality.

I just hate the fact that i have to take off the rear trunk lining everytime i want to adjust the rear firmness....

Someone please give me some advice!!!

Kurtz

iTrader: (1)

The stock springs are linear (ie same rate all the time)... aftermarket springs are progressive (rate changes).

That's one of the reasons I don't have aftermarket springs and got the OEM sport suspension instead.

OEM non-sport springs are 45 N/mm front and 51N/mm rear FYI

The F-sport springs for comparison (also progressive) range from 40-70 N/mm rear and from 47-66N/mm front.

IS-SV

Why change the springs if you want the same spring rates? Are you trying to lower the car maybe? If so a shorter lowering spring with exact same spring rate as stock might contribute to frequent bottoming, and cause the Lexus-like ride to deteriorate.

Lets Drive

iTrader: (3)

You may want to consider BC Racing coils, then. You can specify your spring rates and get trunk extenders to avoid removal of the lining. Perhaps CircuitMS (the vendor here) can work something out with you.

JimIs350

The F-Sport brochure for the lowering springs states the following rates for the stock springs on an IS 350:
* Front: 45 N/mm
* Rear: 51 N/mm

skyshadow

Why would the spring rate be more in the rear than the front?

hocheung20

iTrader: (1)

Just in case anyone works in imperial that's 257.0 and 291.2 lbf/in respectively.

IS-SV

Possibly to deal with full tank, 3 rear passengers, luggage in trunk up to rated capacity (pounds noted in owners manual).