Springs are just part of the overall system. They represent the Bulk resistance to motion. The fine tuning is all in the damping recipe and that is where you see the largest levels of improvments over a stock setup. Typically stock production shocks have lower quality fluid, single stage damping and the big one is that they have no adjustment, so you are stuck with what you have. Also the volume of the factory shocks will be less than a remote or in-line reservoir = less fluid thermal capacity.
The largest benefit of the Penske setup is complete servicability and scability.
The KW setup offers a nice comfort valve for high speed fluid damping, but in general the V3 is not a wide band coilover for the track. Its a performance street coilover for a mostly stock car. That coupled with reuse of stock upper hats limits the dynamic misalignment range as well which makes in not track friendly I would say.

No shock is immune from wearing out and the downside to the OE is that it is not rebuildable. So typically 20-35K between rebuilds is a general number. Penske has stated that one "PROBLEM" they have from a business standpoint is that their shocks just last and last. They will sell to a team and that team never buys rebuild parts because they just keep running the same shocks throughout the whole season.

Just keep in mind it is a system and every component will suffer from the least capable part's performance. Also the tunability implies that someone has to tune it. Adjustments are not trivial for everyone and you can get into some weird modes with bumpsteer and roll center certainly. So its tools that need to be applied appropriately.

Largest differences in setups will be settle time from transition (disruption) and the overall response time on uneven pavement. There are a lot of choices and they all have their place. It depends on what you really want from your suspension and how much you are willing to spend to get it.
KW requires you send them back for rebuild which is a drag, the good new is they will last quite a while before its needed. Bummer though to have to swap stock hats back and have the car down to do it.

 

Lobux and Figs and others...
Thanks for your time and explaining some of the engineering, etc. about springs vs. coilover setups...
I totally understand Lobux's point about time spent by Lexus on OEM suspension vs. aftermarket solutions and that driver skill is the most important factor in "speed" around the track.
It does seem however that Penske coilovers are probably the "best" current solution to drop the car a little, ability to "corner balance", and improved performance of the suspension over stock at the track... I just wish it wasn't 2 1/2 x's the price of the KW's! But I guess I'll just keep saving up and wait till next year.
Figs, so if 20-35k mile rebuilds for coilovers are typical, and Penske's seem to last longer, what is your projected/guestimated miles for the Penske's? Also, do the Penske's have to be sent in similiar to KW, or can a rebuild be done by someone local and therefore less downtime?

 

If you are going to consider Penske and spend that much, also look at Ohlin and Moton. Maybe JRZ too.

 

FIGS is working on a "bolt-on" Penske solution. Ohlins and Moton will require engineering/fabrication to fit and work. All three have some great high end options. I'm a big fan of Penske because they're relatively simple to service.

 

Ohlins for ISF: http://www.ohlinsusa.com/automotive-...+250%2C+GS+460

 

We have also been talking to Ohlins for quite sometime and will be assisting them to create a more specific version for the IS-F. As you can see form factor-wise these will of course fit on an F but the application is generic to all co-platforms.

Mike

 

Translation - will require additional engineering to work properly on the F until FIGS comes up with a bolt-on option for Ohlins. Which is why it is worth it to pay FIGS vs. just order the pieces and trying to sort it out yourself. Unless of course you have plenty of track time and spares to figure out what works yourself.

I'll pay FIGS. Way easier.

 

Also FWIW the Ohlins setup comes with front upper hats, but reuses the rear. the Springs rates are pretty soft by default so we will see what works with there valving.

 

would these be cheaper than the penske solution and when would these be potentially sorted out by you? What's your opinion on the quality/performance/serviceability of the ohlins in general? will they be on par with penske's or lacking somewhat in your opinion?

 

The Ohlins will be in there Road and Track range which is not their full track coilover. The penske will still win in oil capacity and damping response IMO but we are still trying to get these Ohlins on the car to test. They will be cheaper than the penskes though, so it will still be a higher end product for dual pupose vehicles over the KWv3. Sphericla lower bearings and at least the front will have a new upper hat. Its a graduation of what you need and how much extreme driving you will do. The benefits on the high end always trickle down in more comfort on the street, so its not a scarifice necessarily. The only sacrifice will be if you have a really aggressive spring rate to handle shorter travel and sticky tires.

I will post up once we get some time on them.
Fig

 

Figs,
I thought about asking you in a PM, but figured your answer might just help someone out as well.... I was set on Penske's initially, but now we may be building a new house in the next few months and so my "IS F Budget" has been dramatically reduced by the wife.... anyway, so I was just thinking about doing the Swift springs for now and possibly someday doing a coilover... (hence this thread) BUT, now I've been considering the BCR's with the Swift spring option... Would you reccomend this as an "improvement" to the 2011 OEM setup? I know they won't be as "good" as the Penske's but how would they compare to just the swift springs/2011 OEM shocks vs. KW V3's for primarily DD duty with approx 6 track days per year? I just want to make sure that if I went this route that I wouldn't be regretting it... any input would be appreciated!