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Pre-purchase IS350: thoughts and questions on suspension - car purchased!
Hi All
my first post here. Have been reading through a few discussions and build threads (especially redspencer's build) but still haven't got answers for some questions in mind
A bit about myself, I have been driving a mk4 golf TDI for years and has been active on tdiclub.
Now since I moved and dont have a long commute any more, I want more fun lol
So the 2008-2010 IS350 will be a daily driver for me, on road pushing 5/10th with my driving style.
May consider doing a track day a year just for fun. I am in Canada and this car will still be winter driven. Therefore I am not looking to lower any more than 1 inch (prefer stock height to 0.5 inch lowering) Upgrades will mainly focus on improving ride and handling
Questions are as follow
1. Factory SEMI-LSD in the sport package..... I have read some info but still confused. If it is to be plotted on this OS GIKEN curve, what will it look like?
2. Has anyone got good result from square wheel set up (may be 255/35R18?) How does it affect handling on this car? Main reason to go square is for tire rotation for even tire wear. Or is that a bad idea on the IS?
3. How much does the stock 18" and F-sport 19" wheels weight?
4. For my use described above, is it better to go with coilover or adjustable shocks and springs? Is there a recommended set? I prefer something that is similar or better than stock in comfort but definitely handles better than stock. If there is some that can change the setting that would be the best.
5. When looking at a car with stock suspension at 100k km, what joints/bushings are normally replaced as a suspension refresh? What do you recommend replacing with without sacrificing too much comfort? (to me, slight noise and felt bumps are fine, as long as it is still comfortable to do long hour cruises.)
6. What is the recommended alignment for reduced inner tire wear on daily driving but still give a good cornering grip? Can stock suspension bits achieve that or do I need to get aftermarket adjustable joints and links and arms?
That is what I can think of now.
Thank you very much in advance for taking your time to read this. I am looking forward to making the final purchase soon.
Cheers
1. Factory SEMI-LSD is close enough to being useless that you can assume a line at 0% on the graph and be pretty accurate.
2. From a performance street standpoint not a-lot of us run a square setup on RWD cars. The width and diameter (and wheel offset for that matter) that works well on the back, won't work very well on the front, especially if you want to lower the car. Your chosen size of 255/35-18 is probably a pretty good compromise, but it is going to be a tight fit on the front. Also keep in mind that the factory wheels are staggered, 8" on the front, 8.5" wide on the rear.
3. From what I remember the 18" 2006-2008 style wheels were around 25lbs on my scale, I'll check my spreadsheet and update this if that is wrong.
4. The nice thing about coilovers is you get to choose your springs. If you want comfy you can spec a spring that is a bit softer than the standard coilover spring and get that. With standalone springs, you get whatever spring rate the manufacturer chose, and it may not be ideal for either handling, or comfort.
5. I think the front lower ball joint, and the front, lower rear control arm bushing would be the first things to look at replacing.
6. If you are concerned about tire wear, the toe had better be awfully close to 0 on both ends, and you will want to replace the lower rear control arm bushing with an aftermarket part. Camber is less important for tire wear, but more important for handling. Around 1 degree negative camber on the rear and about 1.5 degrees on the front won't affect tire life appreciably, but will help handling. Unfortunate there is no factory camber adjustment. You get what you get through lowering, or buy aftermarket parts.
Other considerations... You say you are from Ontario? SNOW TIRES! RWD + open diff + front weigh bias = not a great snow car. I suggest two sets of wheels, then you can run some decent performance tires during the summer.
1. The factory "E" open-diff is far from useful or fun; if you cannot budget for '10+ IS-F Torsen, ATS Carbon, or OS Giken LSD, then a '11 IS-F steering ecu will not only help with the steering feel but makes adjustments to the amount of "slip" the E-diff gives you to increase your daily fun-factor.
2. A square setup would be useful for multiple reasons; the main reason is giving the heavy beast up front more contact patch to hold itself in the corners. I've read of a few running 245/35 or 255/35 up front. You MUST have the perfect offset (think +35 is the sweet spot) in order to avoid rubbing everything.
3. F-sport wheels are 22lbs and the factory 18" 2IS wheels are 28-29lbs each.
4. Since you're limiting yourself to a 1" drop, you can either select a spring with a 1" drop and a aftermarket shock, or a matched spring/shock combo (Koni kit with 1" drop), or a full body coilover with various spring setups.
5. I'm just about to cross over 100k on my '06 IS350 and believe it or not, there's not really anything in the rubber bushing suspension department that would FOR SURE need to be replaced. However, I highly recommend the RR Racing's USRS; just installed mine a week ago and STILL LOVE THEM!
6. With a 1" drop, you'll not need aftermarket arms/links to get your alignment in spec. Best to request the front toe to be set to 0 and a 1.5 degree front and rear negative camber in my book is good...though slightly out of factory spec. With the USRS LCA bushings, you'll eliminate the notorious 2IS front inner tire wear issue with the uber flexible factory rubber LCA bushing.
I second the dedicated winter tire and wheel setup idea!
1: Ditto to what everyone else has said. Factory LSD is useless. I blow up my inside tire at the track all the time with little effort. Annoys the hell out of my but a true LSD is out of my budget
2: I run a 255/35/18 square setup at the track. I have a set of square 18X8.5 +35 wheels and am running +1.75 camber up front. Love it. No rubbing at all and much less understeer when pushing it hard. You will have to run aftermarket wheels though. OEM staggered wheels will not work. When my street tires are worn out I plan on switching my DD set up to this as well. Really like the setup and tire rotations really save to tire wear.
3: My OEM wheels weigh 29/30 lbs for front and rear. Heavy. My crappy aftermarket wheels (konig milligrams) for my staggered setup run in at 19lbs each.
4: If you want to track your car coilovers are the way to go. The more adjustment the better
5: The only brushing I would change is the front lower control arm brushing with a poli replacement (Figs, ect). This will save you huge on the inner tire wear. There are no camber adjustments on the IS. If you want to play with camber you will have to get adjustable pieces for that as well. Rear is easy with a camber arm. From you need either adjustable upper control arms or ball joints.
6: As mentioned above no adjustability in the OEM suspension for anything other than toe. Aftermarket is the only way to go on that. The LCA brushing is the only way to reall save inner tire wear on the front due to the crappy design of the IS to induce understeer (Toe) during breaking and cornering. I run +1.75 up front and +1.5 camber in the rear and get good life out of my tires since I have updated the front LCA brushing. Before the brushing update I was getting about half the life out of my fronts before the insides were corded.
Glad to hear you are interested in exploring the full potential of the 2IS350 platform, particularly with making the car handle much better than the suspension tuning provided from the factory. I'll touch upon what others have said as the members that replied are also track-minded gurus!
1. I believe that the "semi-LSD" that is promoted by Lexus only helps with traction at very low speeds, particularly when launching hard from a dig. The differential provides no assistance with traction during cornering. The 2IS350 is however equipped with an eLSD (which is part of the VDIM system that manages all stability, traction control, and steering inputs) which activates the rear brake of the tire losing traction during a cornering maneuver. From experience, VDIM is very intrusive and will allow for almost no slip from the tires. As GVille350 stated, you can look into getting an 11+ IS-F Steering ECU which will not only greatly improve steering feel and feedback but you will also receive the bonus of a recalibrated VDIM Sport version which allows the tires to achieve higher slip angles before the system intervenes.
2. SportSkid1 is our CL representative of making a square set-up work. I followed the staggered set-up of the E9X M3 for my configuration.
3. Stock 18-inch wheels are 28-29lbs at the front and 29-30lbs at the rear. F-Sport 19" wheels are 20.5lbs at the front and 21.5 lbs at the rear according to the Lexus F-Sport brochure.
4. Being that you plan on only dropping 0.5-1.0 inch, a high quality spring/shock combo would suit just fine. If you want to adjust the compression and rebound rates to fit your needs, go for a set of coilovers. From my observation, the best track-focused coilovers you can buy are the Penske coilovers that are offered by both RRRacing and FIGS.
5. As others have mentioned, there are no noticeable bushings that seem to have issues on our vehicles. Since you have performance handling in mind, look into replacing your front LCA bushings with an aftermarket option like one offered by RRRacing or FIGS. Improved tire wear, steering response, and braking stability will be noticed when you do this upgrade.
6. Keeping your toe settings close to 0 is what's recommended here. For my set-up, my fronts are 0.03" Toe-out and the rears are 0.03" Toe-in.
My previous reply is still under review by moderator but I have to fire these questions out seeing two new replies lol
1. Is there a part number and source for 11+ ISF steering ECU? Can all lexus dealership do the programming once I get one?
4. In a handling perspective, does our car benefit from lowering at all? or is it going to mess up the roll center, travel and dynamic camber of the suspension which negates the benefit of lower c.g.
2,6. @sportskid1 are you running the positive camber to make your square set fit? Can the square set up fit using stock camber?
hmmm this is weird.... the second reply got posted before my first reply...... oh well let me try again here... and hopefully I still remember all the points.
1. Thanks I guess I am understanding the stock semi-LSD now with all the info.
2. Yes I will have dedicated winters. It seems like 255/35R18 will work with PF01 or konig milligram for my summer set. Can I put 225/40R18 around on OEM staggered wheel set? Back may look ugly but it is winter and no one will see in the snow lol
Talking about snow... for those that winter drive the IS350, anyone has rust proofing done on the car?
3. Thanks for all the info.
4. To clarify my original post, I don't intend to lower just for look. If lowering does not add benefit to handling I will prefer to run stock height lol....
Now another question comes to mind. In the rear suspension set up, running coil over will bring the shock and spring seat to the same point on the lower arm, instead of spring sitting inwards of shock in stock setup. Does that improve or make handling worse?
5. Thanks, front LCA rear bushing is definitely on the list. From my engineering understanding, I think I will get the USRS by RRRacing.
6. Thanks, I will definitely visit a local race alignment shop to get the toe set properly once everything is in place.
I have always run my square setup with that camber so I can't say if stock camber will cause rubbing issues. I can say the OEM camber is around 1 deg (compared to my 1.75) so not a huge difference and if you lower your car you will gain a bit more camber. All in all I have done zero fender mods to my car to squeeze the 255/35/18's up front and have absolutely no rubbing even at full lock. I think it would work with OEM camber settings as well.
Also if you don't buy aftermarket alignment pieces don't waste your money on a high end alignment place. They will have exactly 1 adjustment which is toe and any place can set that to 0. If you go the aftermarket direction for sure get someone who knows what they are doing.
So after driving a few days on rough roads here, I find that stock shock with tein s tech spring is definitely uncomfortable with 19" wheels.
Do you think changing to 18 will help much? or will I have to swap out spring/shock to get a more comfortable ride while still improving over stock handling?
I think you'll have to change up shock/spring combo especially if they're used over 60,000 miles ( average shock life I've seen ).
Popular opinion here is to just buy coilovers for maximum customization. A budget friendly alternative is the f-sport spring and shock combo over a used set of coilovers ( there's a few in the classifieds I saw last night. )
I find that most factory shocks with lowering springs don't complement each other on MOST cars. The shock valving just doesn't match.
Keep those nice-looking wheels and just spend on the money on a nice coilover set. BC Racing is popular and worth every penny; have them myself with over 60k miles on them.
Thanks for the comments
I will definitely upgrade to coilover when the shocks bite the dust, cause I would like a taller ride height for snow in winter while slightly lower for summer
as for the wheels, they are really not my liking. I plan on selling these and use the money to get 18" enkei for summer plus a set of 17" factory for winter
plus, I like square set up more than staggered lol
02-24-16, 05:21 AM
Pre-purchase IS350: thoughts and questions on suspension - car purchased!
I'll touch upon what others have said as the members that replied are also track-minded gurus!
