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Installed: F-Sport Rear Sway Bar...

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Old 06-23-17, 01:59 PM
  #31  
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Originally Posted by Leander311 View Post
Can anyone comment on this? I'm selling my '09 IS-350 on which I'd installed the F-Sport rear sway a few years back, but I'd like to swap it over to the new 2011 IS-F *only* if it truly makes sense to do so! I've read about a bunch of IS-F owners doing it, but with the revised suspension in 2011, it's not clear if it's an actual upgrade for 2011's and later... Thoughts?
Curious about this as well.
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Old 06-23-17, 02:41 PM
  #32  
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I measured the bar on my '14 and it seems to be around 17.5mm. I used a digital caliper, but without lifting up the car so there is some room for error.

My F-Sport bar is on backorder through my local dealer. Hoping to hear back with some news next week.
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Old 06-23-17, 03:56 PM
  #33  
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^^^^I compiled the attached chart a few years ago. I went to a Lexus and crawled under a few IXX50 vehicles. I measured the bars on my F. And Yes, IMHO, it's an improvement for any model year. While the suspension changed over the years, the diameter of the rear sway bar remained constant.

Lou
Attached Thumbnails Installed: F-Sport Rear Sway Bar...-isway-bar-specs.jpg  
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Old 06-25-17, 06:09 PM
  #34  
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Originally Posted by UCrazyKid View Post
The cars intentionally understeer from the factory as a safety measure for drivers on the street. Then F-sport bar that was sold for the IS250 AWD is a perfect compliment for the rear of the ISF. I have one on my 2008 since 2009 and it has been terrific. That coupled with the RR Racing USRS lower control arm bushing/bracket and the car is a blast to take through corners. No exotic suspension necessary.

If I recall correctly the part numbers for the '08 swayer and later years were the same.
You have no idea how many things Lexus did to ensure the car understeers... it truly is legion, and some of them can only be fixed with stiffer bushings. Others cannot be corrected without replacing parts because they literally designed understeer into every single component of the suspension. My opinion of swaybars "correcting" this is well known.
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Old 06-27-17, 01:32 PM
  #35  
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Installed mine last night. It could be placebo effect, but I felt an immediate improvement in stability and a reduction of understeer in long, sweeping turns. I am no racer, nor experienced on the track, but the F-sport rear sway + USRS feel great in unison.
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Old 06-27-17, 01:49 PM
  #36  
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Originally Posted by M4rk View Post
Installed mine last night. It could be placebo effect, but I felt an immediate improvement in stability and a reduction of understeer in long, sweeping turns. I am no racer, nor experienced on the track, but the F-sport rear sway + USRS feel great in unison.
Is the ride quality any worse/bumpy? I wanted to see if the updated suspension in 2011 included this sway bar but from your input, the F-sport bar is an improvement.
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Old 06-27-17, 04:53 PM
  #37  
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Originally Posted by djyoshi626 View Post
Is the ride quality any worse/bumpy? I wanted to see if the updated suspension in 2011 included this sway bar but from your input, the F-sport bar is an improvement.
The F-Sport is thicker. I can't feel any extra NVH - the USRS took care of that already.
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Old 06-27-17, 11:35 PM
  #38  
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Originally Posted by M4rk View Post
Installed mine last night. It could be placebo effect, but I felt an immediate improvement in stability and a reduction of understeer in long, sweeping turns. I am no racer, nor experienced on the track, but the F-sport rear sway + USRS feel great in unison.


This is interesting because a friend and I were discussing how something related to this. He is a development engineer at a particular OEM for automotive suspensions and we were having a discussion on actual peak performance and customer "feeling". He was saying how he was doing some final suspension adjustments that included sway bar selection. The car was a moderate performance type car for street not a track day monster like a ZL1 or Viper ACR. He told me how he was wrestling with the fact that the car performed best "at the limit" during track testing with a set of softer sway bars than previously on the vehicle. He wanted to recommend this but he was concerned about customer perception and usage. I asked him what he meant and he said customers that never approach the peak performance of at the limit handling often feel that stiffer bars are better because they do help the car "react" quicker in street usage. He continued to say that a car that feels great on the street (taking a on ramp or back roads) may feel like trash at the limit (probably on track) with the same setup but because consumers like the feel of a stiffer bar over increased mechanical performance he would probably have to choose that direction.

I guess my point is, you are probably not having a placebo effect, and the car probably does react quicker or give the feel of decrease understeer in a street situation. The sway bar is a compromise made for street vehicles and a fine tuning tool for some race cars. For a street car a sway bar allows you to decrease body roll using a temporary spring rate increase during roll. It is used because you are limited to properly tune the actual springs and shocks to the optimal mechanical performance due to issues with NVH and daily driving. A sway bar is good for NVH because it is has no impact on how the car interacts with "bumps” or the road surface when the car is not turning. It is a very good bandaid for a common street car and what you feel is that increase in spring rate when the sway bar is functioning during a turn. A proper track or race car will have the actual spring rate and dampers perfectly before adding a sway bar into the equation, then the sway bar may be added for fine tuning if necessary, usually if things are designed and tuned correctly a sway bar is unnecessary. I have commonly seen the sway bars of street based race cars removed or disconnected pending the setup or race conditions.
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Old 06-28-17, 12:29 PM
  #39  
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Has anyone installed the front sway bar as well from the kit or just the rears? What price did you pay for just the rears? I see one on eBay for around $178 + shipping.
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Old 06-29-17, 09:54 PM
  #40  
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Originally Posted by djyoshi626 View Post
Has anyone installed the front sway bar as well from the kit or just the rears? What price did you pay for just the rears? I see one on eBay for around $178 + shipping.
from searching, the front are not needed. i believe they are the same thickness .
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Old 06-29-17, 10:19 PM
  #41  
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^^^^It's actually not needed. But the F-Sport bar has thicker walls and is heaver see this thread, Post #2:

https://www.clublexus.com/forums/is-...-an-is350.html

Lou
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Old 06-29-17, 10:37 PM
  #42  
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ah yes. i thought i was replicating what you had told me.
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Old 07-13-17, 06:13 AM
  #43  
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Originally Posted by Piciu View Post
Was there any difference in rear sway bars between '08 and '11 models (with upgraded suspension)?

To be honest I'm a bit reluctant to change sway bar only - suspension is designed as a whole and changing single part is not the way I would go. From my experience with BMW E90 (which had very thin OEM rear sway bar), adding thicker rear sway bar made car more tail happy and it was loosing traction much easier. But it was compensated by softer springs in the rear + adding LSD.

Anybody installed it on '11+ ISF and tracked it? How is traction?
Does turn-in in slow corners (one of biggest issues of standard car according to me) really gets better?
Less under steer in tight corners?
Went ahead and swapped in the F-Sport bar I'd had on my '09 IS350 the last five years over to my new '11 IS-F. IS-F stock rear bar was indeed 17mm. Turn-in is noticeably better, perhaps even more so than when I'd added the USRS. I haven't raced or done any really spirited driving, but initial impressions are very nice.

Also, I'd forgotten how easy it was... the entire swap took exactly 65 minutes without power tools or even jacking the car up at all, including a break for water and clean-up. Anybody looking for a really clean high-mileage silver IS350 in Texas? It has F-Sport shocks/springs, and now a stiffer (than stock) IS-F rear sway!
Attached Thumbnails Installed: F-Sport Rear Sway Bar...-img_1023.jpg   Installed: F-Sport Rear Sway Bar...-fullsizerender.jpg  

Last edited by Leander311; 07-13-17 at 06:21 AM.
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Old 07-13-17, 07:04 AM
  #44  
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Originally Posted by Piston1047 View Post
This is interesting because a friend and I were discussing how something related to this. He is a development engineer at a particular OEM for automotive suspensions and we were having a discussion on actual peak performance and customer "feeling". He was saying how he was doing some final suspension adjustments that included sway bar selection. The car was a moderate performance type car for street not a track day monster like a ZL1 or Viper ACR. He told me how he was wrestling with the fact that the car performed best "at the limit" during track testing with a set of softer sway bars than previously on the vehicle. He wanted to recommend this but he was concerned about customer perception and usage. I asked him what he meant and he said customers that never approach the peak performance of at the limit handling often feel that stiffer bars are better because they do help the car "react" quicker in street usage. He continued to say that a car that feels great on the street (taking a on ramp or back roads) may feel like trash at the limit (probably on track) with the same setup but because consumers like the feel of a stiffer bar over increased mechanical performance he would probably have to choose that direction.

I guess my point is, you are probably not having a placebo effect, and the car probably does react quicker or give the feel of decrease understeer in a street situation. The sway bar is a compromise made for street vehicles and a fine tuning tool for some race cars. For a street car a sway bar allows you to decrease body roll using a temporary spring rate increase during roll. It is used because you are limited to properly tune the actual springs and shocks to the optimal mechanical performance due to issues with NVH and daily driving. A sway bar is good for NVH because it is has no impact on how the car interacts with "bumps” or the road surface when the car is not turning. It is a very good bandaid for a common street car and what you feel is that increase in spring rate when the sway bar is functioning during a turn. A proper track or race car will have the actual spring rate and dampers perfectly before adding a sway bar into the equation, then the sway bar may be added for fine tuning if necessary, usually if things are designed and tuned correctly a sway bar is unnecessary. I have commonly seen the sway bars of street based race cars removed or disconnected pending the setup or race conditions.
A lot of good information here. The only thing I would say is that if you are on a bumpy uneven road, a stiffer sway can contribute to greater NVH when right and left wheels are going over different (sized) bumps/depressions. This can potentially also lead to broken sway bars.
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Old 07-13-17, 03:52 PM
  #45  
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A few weeks in, the F-Sport sway + USRS are worthy budget upgrades if you are looking to elevate daily driving pleasures. The car is also a little more tail happy now. Track day in a few weeks' time, we'll see how that goes.
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