ISF08

Do you remember what spring rating you had on the BC's? BC recommends 12K/10K for the ISF. The spring rates on the KW v3's are 12k/7k. I was talking to someone who works on F1 cars, and he said there is no "track" or "street" suspension. The suspension is designed to mitigate road imperfections and keep the wheels planted, and that you want to get the softest possible springs the car can handle and then get as much damping as possible. This seems to be what KW is going after. I then have an issue with putting German shocks on my Japanese car

hyboost

iTrader: (4)

BC spring rates were 16k/12k

FIGS

iTrader: (11)

Its hard to say because like all manufacturing processes it depends on the assembly line that they are on. All of our BC coilovers go through the custom build queue which means that are assembled in FL from custom valved shock bodies. BC NA will start to offer individual dyno tuning shortly as they are setting up a new facility at the moment for race support. It will cost a little more to run them through this process but if consistency is a concern it will be available. Its also hard to generalize since many people have purchased these from other vendors with the incorrect spring rates or valving or they did not take the time to work through tuning the dampers and used them as it out of the box. We put a lot of effort into support our sales with setup and installation advice, phone support etc. Most ride harshness is related to improperly configured shocks (overdamped). Most vendors would rather violate the MAP policy and defer to BC for support when its needed.

To BC's credit they have worked through the small issues over the years and the current product is better than ever, but its also not as sophisticated a valving as the KW. That being said we have a large instance of customers looking to respring their KW because they bottom with their current setup. The KW setup is undersprung because they only take into account the factory vehicle with no mods. We can offer a custom sprung KW setup or upgrade a KW setup with swift springs, but at that point you are in the same range as the Ohlins RT setup which we feel is a better implementation (full upper hat shock replacement vs reusing the rear factory hat.)

The last variable I will mention is that of the rear bushings, because the can impact the shock efficiency. The staked factory rubber bushing acts as an undamped spring and restricts the shock stroke adding a delay in the damping effect. Our rear LCA replaces the inner bushing with a spherical which nets a more instant location of the arm over the shock cycle. This means more dig traction and overall the shock works better to damp the smaller high speed events. We are able to get more out of the lower cost solution because we are reducing the load on the internal damping and allowing the linear spring to do more work. With each solution there is a compromise.

Mike

FFM

Wow thanks for the response. Restores my faith in the BC's a bit more. I was originally impressed with the build quality when I got them but couldn't dial them in to save my life. Which as the alignment specialist for a speed shop at the time I had a fair amount of experience with tuning suspension.

ISF08

Thought I would update. Found both rear shocks are leaking, may this be a cause for why I am complaining so much about ride quality? Does a leaky shock prevent it from damping correctly? Still not sure what to do. I have the BC's with 12k/10k springs in my FIGS cart and almost order then back out thinking I want to try the KW's...

flowrider

iTrader: (9)

I've been following this thread. I have an '08 ISF. The only suspension mods I have done are:

F-Sport rear sway bar
RRRacing LCA Bushings
Wider wheels (RCF wheels - 255/35, 295/30 Bridgestone S-04s.

I find absolutely nothing wrong with the ride or handling qualities of my "F". IOW, I wouldn't change a thing.

This is truly subjective, however. I have never ridden in a newer ISF, only a friends, who also has an '08.

Lou

myspec15

My 2014 ride smooth

Diesel350

My personal opinion is that if you don't plan on tracking your car the KW's are total overkill.

LexusfanVA

iTrader: (1)

Hate to be the new guy to bump an old thread, but of all the "improving ride on 08 ISF" related threads, this has been the most helpful. I am in same boat as OP, coming from several sports cars(last was G37 6mt sedan on swift springs and 20" with 30 sidewall) I am shocked and almost buyers remorseful at how violent the ride can be on my 08 ISF compared to my G, WRX, Vette, Miata, etc. Almost. My G got bumpier due to sports suspension, and even more so with the springs and heavier wheels, but the stock F has literally made me jump out of the seat and is tough after only an hour of driving on the back(and I'm only 28).

Looking to improve the ride while perhaps going max lower an inch, I've been led to believe something as simple as Swift/Tein springs may help, but BC coils with swift spring rates of 14/10 16/12 or even 12/10 may just do the trick. KW seem amazing but I feel is a bit much both for a DD not tracked car and for the wallet.

Was just curious if anyone had any updated reviews or long term experiences? Can I expect 60k miles/2 years trouble free from the BC coils? Is 14/10 the best for a highway cruiser that may see only 1-2 autox? Appreciate any responses very much.

lobuxracer

iTrader: (2)

For all unhappy with the ride on the ISF, consider the GSF. Bargains are available. The ride is spectacularly better if you are looking for comfort.

The stock ISF is really wonderful at the track. I had more than one instructor comment about how stable the car was in transition with the OEM '08 suspension. It really is all about what makes it good for you.

I really didn't want to like the GSF. It's too heavy. But I do really like it because it's so civilized.

blackisF08

iTrader: (2)

16/12 is gonna give you comfort as well but with the ability to make stiffer if needed, the great thing about bc coilovers is that you can replace the shock at a decent price.

ISF08

I have since left my ISF in the rear view mirror and gone to the dark side that is BMW. In all seriousness, I switched to a sport F30 and the difference is incredible. The ISF did everything so well, but the suspension was just done so, so wrong. Even after test driving a 2013, it was not that much improved, if at all. You CAN have comfortable in the streets and excellent at the track. I know because my F30 is proof. I don't know what Lexus was thinking when they designed the suspension for the ISF but it really is a shame because I love the car. Stiff does not equal performance. If BMW can design a car that corners like its on rails but yet can traverse a broken road without destroying your kidneys, so can Lexus. The reason why I chose not to go down the rabbit hole that is aftermarket suspension is because every car has a large amount of time and money put into it with engineers that design the suspension to a specific spec. Changing that changes the entire geometry of the car, and I would rather not have to deal with that. I also looked at the GSF, and it is nice, and much improved ride quality, however it felt "cheap". By that I mean the ISF felt like it had better quality materials than the GSF, with the F30 beating both. My personal opinion would be this: if you want a smoother riding car, get rid of the ISF. It is just not the nature of that car. Of course, when my warranty is up (7 years/100k miles), I will be getting rid of the BMW as it will be a money pit.

flowrider

iTrader: (9)

I happen to really like my '08 suspension. Only susp. mods I've done is F-Sport rear bar, RRRacing USRS A arm bushings, RCF wheels with 255/35 and 295/30 S-04s. Feels like a different car than the one I drove home 8 years ago. I luv it

Lou

tas02

iTrader: (2)

30 days ago I had Ohlins "road & track" coilovers installed on my stock 2008 f. Along with both front lca bushings and Spoon subframe bolt collars.

At the same time the rubber was upgraded from stock size Bridgestone A/S to 265/35 MPSS on 18 x 9.5" Volk ZE40's front & rear. And a quality alignment w/corner balancing.

It's now an entirely new driving experience. There's no funny noises, scraping or rubbing, just tons more steering feel & less understeer along with reduced roll. And the way the car now rides over low & medium speed bumps is truly amazing especially considering the stiff spring rates (16f/12r) & lowered ride height. The car just glides over road imperfections that used to make me cringe with the stock setup.

The only downside is it won't stop raining long enough for the roads to dry.

LexusfanVA

iTrader: (1)

Congratulations! Sadly I am not one for BMW as I can't stand their interiors and prefer Audi or Benz over them. As far as a GSF suggestion, doesn't really help me as I it's easily twice what I paid for the F. I don't think it's too much to ask for simply improving the ride for under $2k. I guess I'll look into the softer spring rates or try to find an 11+ to compare to and consider just updating the OEM suspension.