737NG

iTrader: (8)

To my knowledge, the platform has remained the same for all IS's thru out second gen. I have a set of BC coilovers from my 2008 IS350 that I never installed , so they are brand new and still in the box. I opted to have the Swift springs installed on them with 14k fronts and 12k rears. So I contacted BC to determine compatibility on the F, and they said they changed the design of the strut for the 2013 MY. They suggested I sell the ones I have now and purchase the newly re-designed ones.
This sounds like B.S. to me, But before I go popping off, I would to get some input from the pros.

Justind27

iTrader: (6)

Hit up figs they know best

Vervish

iTrader: (4)

Shocks and springs were changed in 2012..but not sure if the Bcs will bolt up. I think they should..

ZaxF

iTrader: (3)

I think in 2013 the spring and damper were divorced in the rear. My 2012 wasn't that way when I installed my coilovers, so if you've got a '12 you should be fine.

SoulFreak

iTrader: (1)

To my understanding in 2011 it was heavily revised. 2012, 2013, & 2014. They slowly made adjustments to further tweak/prefect the stock suspension.

streetx

iTrader: (4)

2012 had the revised strut design.

It's why swift has 2 different sets of springs listed for the ISF. The 08-11 and the 12+

ISFpat

iTrader: (10)

The spring design changed for 12+ but thats only for OEM struts. The coilovers for the ISF is not year specific.

Also, I would be against using ISx50 dampers on an ISF. I've done that and it was a TERRIBLE experience. It made the ISF drive worse than stock. The ISF weighs more and definitely needs the coilover valving to compensate for that.

ISFPOWER

iTrader: (20)

it will fit.

but depends how much stiffer you want (prob a lot stiffer) springs, you need the shocks to be revalved for the new rates. but they will mount on.

737NG

iTrader: (8)

Thanks guys, I'll hit up Figs and see what they recommend. If it doesn't work out, I'll post the others in the classifieds.

lobuxracer

iTrader: (2)

How deep do you want to get in this quest?

The real problem is no one is telling what optimum ride height for our suspension is. Without knowing what the camber curves look like and what the natural frequency of the setup is, it's all just guessing. I have asked for this more than once from all the sources, but no one seems to have done the homework. If you measure your chassis and produce the requisite camber curves, you can figure out what setup is best for street or track. They are not the same, and there is no compromise if you are looking for ultimate mechanical performance. I know full well arbitrarily dropping the ride height will potentially put the roll center below ground level which will only make the car look good, but will not make it perform well.

Anyone coming from a real suspension tuning background will either chuckle or LOL at some of the recommendations we have seen here. It's not intuitive and hitting the marks by trial and error will result in a large stock of useless springs and dampers. If you don't do the homework, don't expect superior results.

When I finally take the time to measure it, I will post what I learn here. Those interested in getting the most (mechanically) from their cars would do well to do the homework and understand what the chassis will and won't do. Again, arbitrarily dropping the ride height is more likely to cause problems than to solve them.

We learned years ago that the Supra performs best at stock ride height. I am not confident this is true for the F simply because flipside909 alluded to the ride height being adjusted upward in the production versions to ensure the bumper would not hit parking stops. If this is true, there is some drop necessary to optimize the camber curves and we do not have this with the stock ride height.

FIGS

iTrader: (11)

They are talking about their (BC) design. They improved the rubber upper hat to address the issue with center tube not contacting the thrust washers. It is a nice improvement for anyone that previously had to go through the extra torque on the center nut to assure the bushing would compress. minor details elsewhere as well, but that is the big one.
Mike

737NG

iTrader: (8)

Thank you Mike, for describing the for the differences in the designs. Now the million dollar question, Would you recommend to purchase a new set, Or install the ones I currently have?

737NG

iTrader: (8)

Thank you lobuxracer. This will be interesting to see what you come up with.

FIGS

iTrader: (11)

Well first of all they aren't the right shock for the F, your spring rates are different. So I would sell what you have to a 350/250 owner and get the properly valved and sprung setup from us.
It really depends on what you want to do with your car and what mods you will make plus if it will see any track time.
Mike

737NG

iTrader: (8)

Thanks Mike, I will sell those, then I'll PM. you for a quote.