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Discussion Starter #1
Hi Guys,
To me it feels that the suspension in the F still has some significant room for improvement, especially in regards to the amount of body roll and amount of understeer. I've heard that the F-Sport Rear bar (19mm compared to the stock 16mm) helps a little with the understeer. However, I was looking for a more complete package.

I was wondering if anyone knows if the regular IS250/350 sway bar sets are interchangable? The reason I ask is that it seems that Hotchkis Sway Bar set for the IS250/350 maybe a great upgrade for us if it fits. The front is 32mm vs the stock 29mm, and the rear is 19mm vs the stock 16mm and is also adjustable! Below is the link to the product at L-Tunedparts.com :

http://www.l-tunedparts.com/product/?id=2808

Darshana S...
 

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i would go with the rear sway bar and fater better tires. the car handels amazing stock , what do u plan to do with your car ? that will determin how u should set up
 

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actually i agree on the body roll of the car... i used to own a 350z that i mainly worked on the suspension of the car, i had handling on the highway better than a 360 modena so now with the isf although it is fast, it does have significant body roll when going in and out of traffic at high speeds. Im interested in finding parts specifically for the body roll. Supraman i can tell you from experience that although the sway bars help you would also need things like a body brace and most importantly an adjustable damper suspension or coil overs. Big big difference!
 

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Discussion Starter #4
actually i agree on the body roll of the car... i used to own a 350z that i mainly worked on the suspension of the car, i had handling on the highway better than a 360 modena so now with the isf although it is fast, it does have significant body roll when going in and out of traffic at high speeds. Im interested in finding parts specifically for the body roll. Supraman i can tell you from experience that although the sway bars help you would also need things like a body brace and most importantly an adjustable damper suspension or coil overs. Big big difference!
I definately agree with you about the body brace. I'm hoping a nice fixed end strut tower bar (similar to the one that is avaliable for the GS from TRD) become avaliable soon. I'm not too keen about the coilovers however. My IS-F is my daily driver and a lesson I've learned is that you take away a certain degree of daily drivability when you get coilovers...not too much, but still not as easy to drive as the stock suspension. Plus, I feel that the stock suspension is already pretty well tuned, it's just that I feel that with a bit stouter strut bars it'll significantly reduce the body roll. I'll definately be getting wider wheels to be able to fit at least 255 size tires in the front and 285's in the rear which should help, but once again, you can only do so much to improve handling before you compromise street drivability.
 

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I definately agree with you about the body brace. I'm hoping a nice fixed end strut tower bar (similar to the one that is avaliable for the GS from TRD) become avaliable soon. I'm not too keen about the coilovers however. My IS-F is my daily driver and a lesson I've learned is that you take away a certain degree of daily drivability when you get coilovers...not too much, but still not as easy to drive as the stock suspension. Plus, I feel that the stock suspension is already pretty well tuned, it's just that I feel that with a bit stouter strut bars it'll significantly reduce the body roll. I'll definately be getting wider wheels to be able to fit at least 255 size tires in the front and 285's in the rear which should help, but once again, you can only do so much to improve handling before you compromise street drivability.
Absolutely, so anyone who will be purchasing coil overs for there IS-F BE WARNED! Not so great for daily driving. Fortunately the coil overs that I bought for my previous car was extremely adjustable so it was just as comfortable as the IS-F is right now... However those did cost a pretty penny.
 

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i would like to upgrade my rear bar and brace with F sport. maybe we can get a group buy?
 

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I'm coming from a G35 Coupe. I out on a properly designed STB, and the G turned into a slot car. I needed to do no more to the stock suspension. There were a few STBs out there that did nothing for the G35, but the one I got was a very good piece, and very limited in production. I would love to do something like that to the F, and has been said above, I believe the F is undertired. I will be going to 245s an front and 275s in back.

Lou
 

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i would like to upgrade my rear bar and brace with F sport. maybe we can get a group buy?
I know there was one that Sewell Lexus had a while back but it's no more. Check out l-tunedparts.com or sewellpartsonline.com, they are both forum sponsors of clublexus.com
 

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with the stock setup can you fit 245 or 255 in front and 275 or 285 in the back? cause as it stands now the tires look like they are spares when on the car. they are no way near as wide as they should be.
 

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just found some interesting info regarding rear bar thickness. 10 year-old avalons, camrys and solaras all have 16 mm rear bars. MR2( 19mm) , celica(17.5mm) and supra( 22mm) all have thicker bars. how come a high performance ISF designed to compete with M3 has 16mm rear sway bars???????:confused: that makes no sense for me. that's one of the thinnest rear sway bar in Toyota lineup except for Matrix and Corollas which dont have rear bars.
 

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If search you'll find a couple of previous threads on this

subject.

I've put the OEM IS-F 19mm rear bar in and found it did make a difference over the stock 16mm bar our cars come with. The harder bushings also help add to the less body roll.

The front IS-F bar is the same as the one that comes on our IS-F's, so the only thing you are really getting there are the stiffer bushings, which I am sure will make a slight difference up front, but not enough to justify the added cost for me.
 

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subject.

I've put the OEM IS-F 19mm rear bar in and found it did make a difference over the stock 16mm bar our cars come with. The harder bushings also help add to the less body roll.

The front IS-F bar is the same as the one that comes on our IS-F's, so the only thing you are really getting there are the stiffer bushings, which I am sure will make a slight difference up front, but not enough to justify the added cost for me.
You mean F-Sport, don't you:confused: I also just put in the rear F-Sport 19mm bar, and left the stock front bar alone. Just did this yesterday. Initial observation is flatter cornering. I'll know more with more driving.

Lou
 

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Yep, that's the F-Sport sway bar, and the difference in thickness for the front is minimal, probably not worth the dough.
 

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I think if someone made 22mm sway bars it would be worth the purchase... Cause the stock ones are 16mm. 5mm should make a big difference...
 

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Discussion Starter #15
I think if someone made 22mm sway bars it would be worth the purchase... Cause the stock ones are 16mm. 5mm should make a big difference...
After personally putting in the Fsport rear sway bar and seeing how perfectly balanced the IS-F is now, I would almost certainly say that a 22mm bar would likely not only be overkill but paired with the stock front bar, likely be unsafe because it would result in significant oversteer. I have a Supra TT with Titan Sway bars which are adjustable and when you make the rear bar too stiff, you get a significant amount of oversteer. Trust me, go with the stock front sway bar and the Fsport rear bar and you have a perfect combo. Combine this with sticker, fatter tires, a front strut bar, and you'll likely have a incredible handling car which will likely give the M3 a run for it's money...and BEAT it!!...Darshana S...
 

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Supraman, I talked to Clark at Vip Auto and he can get the TOM's front strut bar from Japan. I would email him if your interested :cool:
 

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just found some interesting info regarding rear bar thickness. 10 year-old avalons, camrys and solaras all have 16 mm rear bars. MR2( 19mm) , celica(17.5mm) and supra( 22mm) all have thicker bars. how come a high performance ISF designed to compete with M3 has 16mm rear sway bars???????:confused: that makes no sense for me. that's one of the thinnest rear sway bar in Toyota lineup except for Matrix and Corollas which dont have rear bars.
There is more than just the overall diameter of the bar, the shape of the bar as well as the wall thickness of the bar influence how stiff it is.

Stiffer isn't always better either, if you over do it, it can become very difficult to drive the car on the edge.
 

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After personally putting in the Fsport rear sway bar and seeing how perfectly balanced the IS-F is now, I would almost certainly say that a 22mm bar would likely not only be overkill but paired with the stock front bar, likely be unsafe because it would result in significant oversteer. I have a Supra TT with Titan Sway bars which are adjustable and when you make the rear bar too stiff, you get a significant amount of oversteer. Trust me, go with the stock front sway bar and the Fsport rear bar and you have a perfect combo. Combine this with sticker, fatter tires, a front strut bar, and you'll likely have a incredible handling car which will likely give the M3 a run for it's money...and BEAT it!!...Darshana S...
i agree. the stock setup gives a mild understeer and may take a slightly thicker bar to make it more neutral. there are a few things to consider when putting in a stiffer rear bar. the balance between front and rear suspension is critical. the front is a hollow bar which does not provide as much stiffness as a solid bar. going to 22mm or thicker would be extremely stiff compared to the hollow front bar and can creat excessive oeversteer. another factor to consider is that it takes very little more thickness to double stiffness. that's why the F-sport bar is only 3mm thicker than stock. a 22mm or other very thick bars may be ok, but without documented safety and handling characteristics, i would be very cautious.
 

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OK, more information here. The stock sway bar for an IS-F is not 16mm as has been widely reported on this and other forums (and in this very thread). I contacted Lexus 3 weeks ago and asked for this information, they finally got back to me yesterday. It's 17mm. Just to be sure, I borrowed a set of calibrated calipers this morning and measured my bar, it measured 17.2mm. So, it really has an OD of 17mm. I don't know where the 16mm came from, but it is very wrong.

Lou
 

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You mean F-Sport, don't you:confused: I also just put in the rear F-Sport 19mm bar, and left the stock front bar alone. Just did this yesterday. Initial observation is flatter cornering. I'll know more with more driving.

Lou
now that you have had it for a while any new thoughts? I just ordered one, but for only 2mm I am concerned it is worth the money?

thanks
 
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