Carnevino

I've run KW on three different platforms. Outstanding performance and build quality. KW has long been considered one of the very best money can buy. It's on par with Ohlins. With that said, I'm going with the this Penske set up because I know the quality of the Penskes is arguably a notch higher in quality. These aren't cheap and you get what you pay for. I'm an owner of a major online auto parts store out of Las Vegas....I can afford to put any part I want on my cars. You won't be disappointed in either set up. The new KW does have the umbrella system for the RCF which is pretty cool. If you have a steep driveway or a high speed bump then they will raise the car up a few inches to get over most obstacles. A friend has this set up on his GTR and it's pretty slick! I like driving my cars pretty hard, so the higher spring rate doesn't concern me. If you want a cushy ride with just a little low I'll sell my RSR springs to you next week for 150$. Man I get your concerns, the RCF is your baby and you're wanting to get some insight into a proper suspension set up. Maybe sit back a few weeks and let us that purchased the Penskes give a long term review. You'd be shocked at how well a REALLY good set of coil overs can perform for everyday drive ability....they really do ride better than what I "think" you might be feeling

jsmacks

..thanks Carnevino.. point well taken.


I have to laugh on this one.. people are amazing sometimes..

If we're now at the point that simply asking for further information is deemed "trolling", then things have reached a new low. Sorry/not sorry if you're offended by that. Two thumbs up for barging into someones thread, posting OT content about a different product that wasn't even asked about, then screaming "TROLL!!!!!!!!!" when asked for simple quantification on your hyperbole. We've got a special one here. Protip: You're not helping your buddies by publicly acting like this.

I do appreciate the other non-fanboi responses and will keep looking. Leaning towards the KW setup at this time, especially after what I've seen here..

weswork

iTrader: (4)

I've also had KWs on a number of vehicles and been very happy with them. They have been the V3s each time. I have heard that the springs rates can be a little on the softer side but they were definitely an improvement over my stock suspension and the HKS Hypermax IIs I had on my Supra. At least at the time, KWs were also dyno tested for their applications. You also have the option of changing spring rates or swapping to Swift or other potentially "better" springs but, that will obviously add cost. I will tell you the one thing I have been disappointed with with the KWs is that in each application I had to have some modification done to the mounts in the front for them to fit right. Although it was minor, it still had to be done and needed to be left to a professional. Based on the way you have outlined your needs I don't think you would be happy with lowering springs. Although it will likely be some improvement, you are stuck at that height. I am getting lowering springs first to see how it goes but, am somewhat concerned about being 1.3" lower for my daily driver. Just thought I would provide some additional perspective. I may end up with Penske but, want to get a little more feedback (like you), am not completely sold on the eibach springs that are used with this setup (vs maybe a higher quality spring), and it seems like there is a recommended height setting for these which may be to low FOR ME and a daily driver that will likely not see track time.

FIGS

iTrader: (11)

I think it really comes down to what your end vehicle goals are an how you will use them. The KW V3 system is designed around a factory spec car with the only the dampers changed and set to a slight drop. Any additional option to account for added power, weight or traction is additional and technically outside of warranty. KW uses an inertial valve technology and tend to be under sprung by at least 2K because they choose to use their patented valve technology to control the fluid. This valving usually makes them more comfortable in high-speed fluid damping but not as linear a response. We were the first to run the KWv3 on our original IS300 development vehicle in 2005 and as weswork suggested since they do reuse factory hats, the keyway requires modification. It's not a huge deal, but some applications are starting to come with upper hats as well, depending on how popular they are for KW.

We do not have experience with RSR so I cannot comment.

We were the first to deploy the Penske 7500DA series shock on the IS-F and the majority of the increase in performance is related to the precision of the internal components, the amount of shims they use per valve stage and the seamless transition between high and low speed damping that their valve design provides. The downside with a Penske setup is the spherical connections one both sides will add additional noise which will require maintenance. We have run our setup for 4 years on our IS-F and the noise can be contained with frequent dry lube. While the shocks are still our favorite on the vehicle, damping adjustments do take some time as the compression is set at the base of the shock via hex key and rebound on top with a 1/8" thin hex making it less friendly to full trunk liner setups. Chances are you might not make too many adjustments but the initial setup is based on preferences and it might take a little iteration.

We were also the first to do a coilover conversion on the 3IS platform (similar rear suspension) during our involvement with the N1 racing IS250 back in 2013 during the 25hrs of Thunderhill and we offered it in our initial thread asking what people where interested in in terms of suspension.


With the weight distribution of the RC-F being different that the IS-F I would say it requires different spring rates, even with a true coilover as more weight sits in the back of the car than the front not to mention the total vehicle weight is higher.
We can provide a Ohlins road and track true coilover setup that is sprung for the RC-F with or without TVD and that would be a rubber bushing or even poly bushing option that would not have any noise issues over temperature. The R&T setup would still be a dual valve setup for high and low speed damping ranges but would be a single adjustment vs compression and rebound divorced setup of the 7500DA. Our Ohlins customers have been extremely satisfied on the IS-F platform and they would fit more of the profile that you seem to want. They would be similar to these below (ISF version) we would just make valving and spring adjustments with more rear bias on the RC-F. An added benefit is that they would also still have a non-preload ride height adjustment on the lower section to allow easy ride height tuning. The Penske and KW both adjust via spring preload/helper spring combo.





In the end there are a lot of choices now and more coming out of Japan so I would not constrain yourself to 2 options.


Mike

jsmacks

THANK YOU THANK YOU THANK YOU, Mike and weswork for straight up, articulate, thought out answers. This is exactly what I/we're looking for. So awesome. Not sure if it was you, Mike, that I spoke with on the phone the other day while ordering our essential kit.

As with anything, so much of it comes down to what your intended application is for your setup. Dead right. My concern with the Penske isn't of quality, it's that they may be a little stiff and too track oriented.

At risk of sounding like I'm just trying to lower the car and nothing else, I'll be honest and say that my sole concern with the KWs at this point is that the max drop is only 1.2". On top of the overall quality/design, I'm really liking having both compression and dampening flexibility instead of just dampening as with other systems. I'm super concerned with the quality of the roads here.. they're gnarly in spots. I need something that can handle it all and yet gives us that flexibility to adjust.

I'm really, really liking what I see above. A lot. Curious what your ride height adjustment range would be on an RC F setup?

You can post here for public reference.. I'll be calling tomorrow regardless..

FIGS

iTrader: (11)

Here is a video from KW that explains how their valve design works. you can see that use a decoupled fluid path because they are twin tube dampers.

The Penske shock is a monotube damper and thus the low speed bleed valve is controlled in the center of (through) the damping shim stack with preload being added the to high speed shim stack on adjustment as well. This is a video that shows the shaft and piston assembly of the 3 way 8760 (I think he says its an 8780) but the 7500 is similar it just has fewer bleed adjustments.



The best way to think about this is that the springs adjust your total travel and energy storage and the damper controls how fast it will get to the total travel and how gracefully. In many cases a good valve design can be more diverse and therefore you will need less gross adjustment in the bleed. The higher spring rate just means less gross travel and in the case of lowering, you just reduced total shock stroke so you have less runway so to speak to capture the energy, the spring rate has to increase. With spring rate increase, the demand on rebound damping increases because you just started to store more energy on compression and it wants to return to its rest state and that is your comfort setting. How quickly the energy is returned is more of your perception of comfort and also keep in mind that the front and rear are constantly swapping energy as well as the weight of the car transitions.

KW's ride height recommendations are chosen based on stroke and the spring rate they chose to avoid hitting the bumpstop on compression and increasing the life of the shock. So you can certainly go lower, you just need to increase the spring rate accordingly to catch travel in time. Warranties are void by going lower because it increases the head pressure of the fluid and puts higher demand on the seals etc creating more wear, so if we put more of the energy into the spring it will save the shock internals as well. Anything can be tuned but KW insists on the clubsport coilover for that purpose, which is quite a bit more expensive. The v3 is not a track coilover, it just cannot keep up. Its a street performance coilover plain and simple.


Mike

FIGS

iTrader: (11)

Regarding the Penskes, the 7500DA tech manual is readily available online to look at. it will show the dynamic range of the damping and the valve design as well. The important thing of course is what's inside and we leveraged the vast experience of the lead shock tech at Penske to setup our IS-F configuration (another reason it took us 3 years as it was tricky to get his time in between indycar and champ car support.)

http://www.penskeshocks.com/assets/T...A)%2008-10.pdf

RRRacing

iTrader: (1)

A few points I want to make just so that there is no confusion:

(1) Due to the low spring rates and the fact that KW reuses all the factory upper top hats and rubber isolators, there is no question that KW is the quietest and most OEM like setup. But having driven the KW V3 equipped ISF, it is also clear that the KW setup is simply not a high performance suspension, it is very much street oriented. I would argue that good set of lowering springs and perhaps an adjustable rear sway bar would yield similar performance gains without spending $3000.

(2) There is no question that the RCF, especially due to its higher weight, would benefit from even higher spring rates then our standard setup, on the order of 18F/16R for more aggressive street/track setups. We chose the 16F/14R as our standard combo because it is a compromise between street and track performance with more emphasis on road comfort. Our standard spring rates are still 60% higher than RSR. We tuned the suspension for very mild at the limit understeer, and this was confirmed by track testing at speeds up to 145mph.

(3) No need to scare away folks by suggesting a Penske setup is noisy: We have completed already a 1/2 dozen RRR/Penske installs over the course of nearly 6 months, without a single complaint about noise. The only "noise" generated is very minor and only audible on very rough back roads, at low speeds, with engine running quite at <2500rpm. We design and manufacture our own top mounts and use very large oversize spherical bearings mounted in Teflon polymer which are very durable, easily serviceable, and effective at minimizing any noises. We also isolate the springs front perches using Delrin isolators, and polymer spring couplers. The improvement in performance from using spherical bearing mounts and decoupling the spring from the top mounts is worth it for those searching for the ultimate suspension package.

(4) Fast turnaround time and service: We are able to work closely with Penske on development and service because we are located 20 minutes down the road from Penske Racing Shocks Headquarters in Reading, Pa. We can turnaround almost any repair or service in a matter of 1-3 days. No need to wait for parts from Japan (Ohlins) or Germany (KW). Penske keeps every part in stock at all times, and everything is made is USA (for those of us who still care about that sort of stuff).

(5) We do not theorize on how the RCF would behave on the track compared to an ISF based on weight distribution (which is actually very similar... RCF = 54.6F/45.4R, ISF 54F/46R)... we actually brought TWO RCFs to the track both setup with our RRR/Penske's! We waited months to release our RCF suspension until we actually track tested it, until we had the experience to back up our claims.



Track Testing at New Jersey Motorsports Park Lightening Raceway

ROK

I'll never do business w/ vendors who sell on spec w/ a sprinkle of FUD rather than focusing in on the customer's stated desires and iterating from there.

And also those who bring specious, questionable, unrepeatable "R&D" w/ limited budget, backed by little to no references.

This thread is trash, imho.

FIGS

iTrader: (11)

Interesting that there is no noise, but that there is a little noise only under low speed and low engine rpm situations. That is the exact case I am talking about.

Teflon-lined bearings have what is called F2 fitment as standard meaning they require slight torque to break them free. Penske uses Aurora COM-T bearings in the lower mounts which are teflon-lined and can have low speed stiction from the break torque that is amplified by the coil spring resonance (like a tuning fork). It does exist and is worth noting for anyone that is considering the setup. Bearings are metallic components and with varying temperature as we have in CO, the do change their fit and the thermal expansion and contraction change the joint properties.

Its not helpful to compare spring rates on dissimilar motion ratio suspensions (stock vs coilover in this case) as of course the rates are different and the balance is different. Spring rate can be curbed based on the shim stack of the damper and with bumpstop modifications plus the overall damper design. RSR chooses to use a very low rate for some reason but that is their determination of what the market is looking for. Some might find it suitable to their needs while other will demand more.

I bring up the IS250 AWD test case because that was a 25hr endurance race, with a suspension geometry that is nearly identical minus the aluminum components. We had 5 seasoned veteran race drivers in the car and made adjustments based on their feedback. Bumpsteer is different on the RC-F platform so the travel limits need to be set differently than the IS-F.

Our experience is with a blend real world and track testing as well as long term considerations rather than a single track day event. We will rapidly vet the RT setup for those interested as this has been sorted out for the past year waiting on solid interest. I would also note that our previous iterations have been minimal due to our strong application of theoretical and real-world test data. Our deadline is first week of Dec. to get this case done.

Thanks Mike

jsmacks

EXACTLY! I don't even need to comment too much at this point.. as all of the above speaks for itself. I can't tell you how happy I am to have this type of intelligent discourse happening! This is exactly what I was looking for.


My decision just came down to two final factors:

- I need a setup that's directed towards my intentional use of the vehicle. My car will never see a track a day in it's life. I need something that will perform as best possible in my real world conditions.

- I trust FIGS. A lot. These guys live, eat, sleep and breathe Lexus suspension. I don't care what widget you purchase in this world, but if it's something you truly care about.. make sure to get it from someone that dreams about it in their sleep.


That being said.. I'm concrete on the list for a set from Mike as soon as they're ready in a few weeks.



Or is it? I think it may be one of the most important and revealing discussions involving currently available RC F suspension setups on CL to date. Think again..

RRRacing

iTrader: (1)

The "noise" is very insignficant. In fact, regarding the lower shock mount bearing, back during our ISF Penske development project we experimented with 80 & 90 duro poly bushings to replace the Aurora lower mount bearings. The difference was imperceptible, so we decided not to even offer it as an option.

Another contributor to the insignificant noise is the rebound setting of the shock. There is no question that backing off the rebound makes a difference, and that is something the user can easily do because the rebound adjusters are located a the top of the shock. Knocking due to high rebound rates a consequence of high spring rates (high energy that must be absorbed by the shock), and one of the major reasons OEM manufacturers are limited with their spring rate choices.

Again, so far, we have ZERO negative feedback concerning NVH with our ISF or RCF coilovers. If we have requests, it is not a problem for us to dampen the spring perches with rubber isolators like Ohlins does, and use poly bushings on the lower mounts. Its just a shame to do it, because you loose some of the precision and feedback you gain from removing the isolators.

Although we settled on similar standard spring rates for our ISF vs. our RCF coilovers, obviously there are differences in suspension geometry which warrant a complete redesign of the ISF suspension when adapting to the RCF. Our ISF and RCF setups are significantly different, including valving, bump travel, and bump stop length & durometer.

Incidentally, bump travel on the ISF vs. RCF front suspension is very similar even though each is based on a different chassis (IS vs GS).

-Rafi

RRRacing

iTrader: (1)

Just want to emphasize, that everything that I have spoken of in terms of NVH reduction, we have already experimented with and tested.

We will gladly offer these options, although we do not think the majority of customers would benefit from it:



Optional lower shock mount bushing




Optional rubber coil spring isolator

RRRacing

iTrader: (1)

And one last thing... we are developing a full electronic damping control option for our ISF & RCF RR-Racing/Penske coilovers.

This means that you can adjust rebound as a function of:

(1) Pre-programmed presets... just select a mode, and all 4 shocks are automatically adjusted to your preset preference, anything from "comfort" to "race."
(2) Speed based control -- reduce rebound at low speeds to reduce noise an improve ride comfort... increase damping at higher speeds for control.
(3) G-force based adjustment -- automatically increase damping levels as a function of g-force.



In development: electronic damping controller

sraban

Get the RR Racing Penske, like several other RCF and IS-F owners did, and you will be able to quantify their advantages for yourself! I can guarantee you that if you drive Penske and compare on the same car to KW or Ohlins, you will not argue that the difference in handling quality is obvious. Add the RR Racing USRS (lower control arm bushing with newly designed housing), and you will feel the same difference in your steering response.

Penske is the standard in racing shocks -- all top racing teams use Penske -- so there is no argument whether Penske are the best (even see Figs comments in this thread). The question is whether Penske shocks fit sportive street driving. RR Racing has more Lexus (IS-F and RCF) cars equipped with Penske suspension than any other company. RR Racing experience as well as of our customers is that Penske is great for both track driving and sportive road/street driving (of course, if you just driving to a grocery store and the office at the speed limit, get some lowering springs or do nothing).

Penskes have a very comfortable ride on the street and it is almost as quite as any aftermarket shock. This is the amazing thing about Penskes! Penskes was developed and tested on many different race cars and was tested by RR Racing considerable on both uneven and windy country back roads, highways, and the track. Penske Shocks headquarters is just 30 minutes from our shop, and we worked extensively with their engineers and technicians on these shocks. There are very few people who know shocks better than Penske engineers.

So, to summarize, anyone who wants to buy reasonably priced, best handling double adjustable shocks on the market that are well suited for both the track and the street, should look at RR Racing Penske coilovers. People who just want to lower their cars, should consider just getting new springs. I do not understand why anyone with a $80K sports car would downgrade their suspension to KW or RSR.