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Alright, this thread has been dead for awhile. Since this thread was started over a year ago, I wanted to update for those who would consider replacing their stock is350/250 rwd struts with 2008+ Isf struts. About a year ago I started this thread wondering if anyone had tried running ISF oem suspension on an Is350. To my surprise no one had, so I took a shot at it and it has now been over a year since.
So since the mod I've had a chance to to Daily (in all conditions, rain, snow, summer, ICE!, dirt) and have about 7 track days on them on multiple formats including auto x, road course, and winter cross (essentially autocross hpde on a track with snow and ice).
Performance review. (Mind you I have front and rear sway bars also..)
This review isn't just ISF strut/shock independent.
The suspension holds up to any abuse very well, being an Oem setup it acutaully still drives pretty smooth, but it also makes the daily drive alot more spirited knowing that the response you get from a stiffer setup is alot more exhilarating. I commute daily to work and have gone on multiple road trips to Chicago from Minnesota. It IS stiff, and there is some rattle when I hit cracks/bumps in the road but I'm gonna blame that more on the sways, It has never been unbearable (for me anyways). A point that alot of early F drivers stated in the beginning was that the Isf suspension was too stiff, but I don't think at the early stages alot of people were accustomed to the fact that this wasn't your normal, driven on clouds and pillows type of Lexus, this was a Lexus developed and engineered at the track also. Lexus spent alot of time fine tuning the suspension so that it could attempt to be comparable to the Bmw M3.
In terms of track performance, this is where it really shined! Alot of people may have discredited the 08 ISF suspension solely because they had only saw it from a daily driving aspect. After driving it to its potential on the track, you really get a sense of what Lexus was trying to accomplish when it came down to building a car donning the F badge. I in no way claim my is350 is anywear near that, but when you add some true F parts, you do get a slight hint of F performance.
I still have not felt the need to get coilovers..Yet. I have been looking though! I just haven't felt it was necessary yet, I feel I haven't out driven the suspensions potential. I'm still playing with tire setups to optimize the full benefit of this suspension and just finished adding the rest of my go fast bits.. intake, full exhaust (including headers).
I know this is kinda a general update, but for the year I've had this setup the only thing, like most ISF guys experience, is that I wish I had the ability to adjust the front height.. but not a big deal. For the $200 I spent on this suspension, it was WELL worth it. The ability to have an oem upgrade based on interchangeablity is a beautiful thing. I experienced this in the Honda game and it made for a good time knowing that you could upgrade performance with piece of mind that you have oem quality (an OEM upgrade) so to speak. I suggest you make friends with an F guy and reap the benefits of getting these upgrades for cheap. Money saved on parts, buys you more time at the track!
If you are looking for better handling and are interested in autocross/track, look no further for coilovers. You can adjust the ride height and dampening settings all to your very liking. A good value one that fits many people budget and perform decently should be BCR coilovers. I believe a member track junkie sportkid runs this set up. I have recently installed this on my IS250 (I have 2 IS haha). The stiffer spring rates you choose, the less body roll during cornering but also stiffer feel. In addition, the dampening settings can really change the way you feel as long as you have enough suspension travel, meaning if you lower the car height too much, you have to set the dampening a bit stiffer so you don't scrape or bottom out so ride height influence this too.
If you are into lower spring set up, I highly recommend F Sport lower springs + F Sport shocks. I have personally run this set up on autocross, track pushing it hard and it provides wonderful, controllable and predictable handling. On street, it is comfortable like OEM and more comfortable than the coilover set up (subjective personal feel based on 2 cars I have). This set up has been specifically designed and tested by Lexus engineers and validated by professional racer. Another track junkie redspender also runs this set up on track and love it very much, so do I.
Here is me in IS350 with FSport springs + F Sport shocks + F Sport rear sway bar set up running on autocross
Do not pair any lower spring with stock shocks because the shocks are not valved correctly to match the spring rates on them. On progressive springs like Eibach, H&R and many others pairing with stock shocks (both sport or non-sport shocks alike) will give you very unpredictable handling. Also, at uneven road, the shocks don't absorb bumps well so it is very jarring ride. I have tested this set up on street and autocross and hate it. Don't waste your money. if you go with lower springs, you must pair it with a shocks that are designed to work with stiffer springs such as F Sport (Bilstein) shocks, Koni Yellow and make sure re-valve them. But with this much money, you are even better off getting the coilovers.
Bottom line, I highly recommend Coilovers or FSport springs + F Sport shocks.
wow, thank you for the thorough feedback, I would love to go the coilover route as I have run coilovers in the past but my budget as of right now are dedicated to other things. I still need the necessities like Pads and fluids..also doing stainless steel lines. I am mainly focused on running a wider wheel setup with a set of dedicated track tires (which is priority before coils), which will ultimately free up some unsprung weight for me, and will get me out on the track quicker this year than if I hold out longer for coils.. cause ill still want to shell out for wheels and tires.
I would have loved if there would have been any input on the ISF suspension setup just considering that they could stiffen up the Is350 suspension a little more. also do you recommend any camber kits to help with performance aligning? would that do more in terms of making the car a little better at handling, I tend to notice that the IS gets a little choppy in tight turn, could probably use some negative camber.
the reason I am considering the ISF suspension is that it is an OEM alternative that could either make the car a little better or worse, considering that its what I already have. I tracked a civic I built last year on a pretty good budget and was doing very well out on the road course here, all I had were sways and Integra suspension, motor work etc..
I sold it to get a more practical car (My Is), so it is a completely new platform for me..
Believe me when I say that I will get coilovers at some point.. I really want the fortune autos, but at $1000+ I just want to be able to make it out to the track and get some needed seat time in this new platform/drivetrain (to me), so I can suffice on stock suspension for now but just needed some reassurance on whether or not the ISF suspension would benefit me at all or..would I be better sticking to stock.
What year is the IS-F? If it's from a 2008-2010 IS-F, I personally wouldn't purchase the suspension set to install on an IS350. Lexus didn't get the suspension tuning right on the earlier IS-Fs and it wasn't until 2011+ when a revised suspension was implemented which really improved the balance and compliance of the car.
Here's an informative thread from the IS-F sub-forum on the difference between the 08-10 and 11+ IS-F suspension for your reference: https://www.clublexus.com/forums/is-...-2008-isf.html. One of the IS-F posters summed up the older IS-F suspension tune quite nicely: "It's pretty bad. It is uncomfortable, car doesn't feel very planted, body roll is pretty high.
As FSportIS stated, you should probably look into getting coilovers or the F-Sport shocks/springs combo.
I agree with you guys and will look towards those options when I can save up enough to do so, I am really happy to get the feedback I'm getting and appreciate it greatly! I think its worth a shot and I really have nothing to lose by trying it, I am gonna attribute some of the Isf woes to the actual car itself being bigger/heavier, with a slightly wider wheel base/ geometry, but I think the shocks and struts of the Isf may somewhat help the Is350 considering that its lighter, I'll make sure to post up a review or feedback on this, I wont be at the track till June so it will be awhile, and my next track day after that won't be until September so I'll be able to see if the Is with Isf suspension will be composed, I do have the f sport sways also
wow, thank you for the thorough feedback, I would love to go the coilover route as I have run coilovers in the past but my budget as of right now are dedicated to other things. I still need the necessities like Pads and fluids..also doing stainless steel lines. I am mainly focused on running a wider wheel setup with a set of dedicated track tires (which is priority before coils), which will ultimately free up some unsprung weight for me, and will get me out on the track quicker this year than if I hold out longer for coils.. cause ill still want to shell out for wheels and tires.
I would have loved if there would have been any input on the ISF suspension setup just considering that they could stiffen up the Is350 suspension a little more. also do you recommend any camber kits to help with performance aligning? would that do more in terms of making the car a little better at handling, I tend to notice that the IS gets a little choppy in tight turn, could probably use some negative camber.
the reason I am considering the ISF suspension is that it is an OEM alternative that could either make the car a little better or worse, considering that its what I already have. I tracked a civic I built last year on a pretty good budget and was doing very well out on the road course here, all I had were sways and Integra suspension, motor work etc..
I sold it to get a more practical car (My Is), so it is a completely new platform for me..
Believe me when I say that I will get coilovers at some point.. I really want the fortune autos, but at $1000+ I just want to be able to make it out to the track and get some needed seat time in this new platform/drivetrain (to me), so I can suffice on stock suspension for now but just needed some reassurance on whether or not the ISF suspension would benefit me at all or..would I be better sticking to stock.
Great, tires tires tires and stickier tires yields better gforce and will transcend the car handling a whole lot. Of course wider wheels offer even more traction. This alone will save you second or even seconds on a technical autocross or track. You are going the right route.
The reason the IS platform get choppy during hard braking/cornering is mostly due to the stupid safety design of "dynamic toe change". Do you know that our car change toe settings during hard braking/cornering to create understeer regardless the weight transfer is to the front to offer more grip. For this reason, you should get a Fig #2 bushing which is stiffer to reduce this stupid toe changing tremendously. I'm about to get this thing soon. Here is the video that demonstrate this
Our IS have no camber adjustment but the natural camber is pretty good. My car is lowered about 1.5 inch or so and I got about -1.3 to -1.8 natural camber. However, you will benefit a lot more if you can adjust the camber with the camber kit for even better performance. Yes, I feel some negative camber (NOT ridiculous camber on slammed cars) do helps corner better.
ISF suspension (if you able to fit it on our ISX50) will definitely stiffen up the handling. I heard that the earlier year ISF has softer suspension than the later year ISF. I have not tried ISF suspension yet so I really don't know how it fare. However, the handling figure Gforce, slalom speed figures are pretty impressive. I think this will be great set up and great value because you only spend like $100 lol so nothing to lose. I would like to hear your feedback on this set up.
Also, my personal opinion, I would suggest you try a bone stock IS350 on the track one time first before you do all the crazy upgrades for 2 reasons:
1. You will discover the limit of the car in stock form.
2. Once you start doing your upgrade, you know the improvement of that upgrade because you have a base benchmark. Therefore, you will appreciate your upgrade a lot more than if you just slap them on without the base bone stock comparison.
Another thing I would like to add is brake brake brake. Our IS350 stock brake set up is good but will still fade under heavy usage. I would suggest you save your budget for a more aggressive pads that can take high temp such as Hawk high performance track pads together with a Stoptech cryo blank or slotted rotors (do not get drilled) with steel brake lines and Dot 4 fluid that can take higher temp.
damn ^ all of that was great insight and information!
I did not know that our cars had that safety feature with the toe settings, I was always wondering if it had anything to do with it not having a true differential, but that is definitely new info for me! So i hope to resolve that.
that is also good insight to run the car stock for a benchmark. I'm not expecting the Isf suspension to be night and day, I just hope it is a little stiffer. I know bushings help to, I also had that on the civic.
I agree on tires being important because a really good set cost alot and make a HUGE difference, I ran falken azenis and they werent very expensive for the civic considering tire size was 15's, but for the size ill be needing to fit a 18x9/10, ill probably shell out over $1k. thats why its so high on my priority.
I stand behind Hawk Pads, I ran Hp+'s in the civic and they were incredible, I use to run Ate superblue dot4 but apperently that is now banned for distribution.
Cool, I'm so glad to see another autocross/track junkie on ClubLexus. So far, I believe we have Sportkid, redspencer, me, Rsuave24, Gville350, and couple more (please jump in here if you will) who are into high performance driving and handling performance.
I would certainly wish more and more members will be going to focus on handling performance and driving dynamics more than just slamming cars.
Well I know this might not matter to most but I installed the strut assemblies from the ISF on my 350 yesterday. Overall the ride did get a little stiffer and is slightly a little more responsive. I would have taken a picture to compare the struts but my camera died. the struts are CONFIRMED a direct fit. comparatively though the isf strut assemblies are slightly shorter. so in that aspect I actually also received an Inch of drop. come june I will be able to give some performance updates after my track day!
the track ill be running is Brainerd International Raceway here in Minnesota. It is an awesome course and I very excited to run the setup. I hope to someday get out to a track day at road america, but for the event ill be attending, Modern automotive performance's Proving Grounds, it is a great deal for seat time. 6-8 twenty min sessions at $160 bucks.
Glad we have another member getting into the track world. So much fun. Also if you decide to get a dedicated set of track wheels I would strongly suggest getting a square setup. I am running 18X8.5 +35 with 255/35/18 on all corners. The bigger front tries really help in the understeer that is so bad in our cars. Plus you can rotate them so my tires are lasting 3-4 track days loner than in the past.
these will be my dedicated track wheels. i am running a square set of rota grids 18x9.5 with 275 40 18s in the rear and 245 35 18 in the front, ill be swapping the tires for a square set up for sure.
01-11-15, 07:35 PM
Isf Suspension on IS350 Updated!
