SJ408sgmIS

iTrader: (2)

Does the F-Sport Rear Chassis Member Brace really help the suspension? Or is it better to just get the front & rear F-Sport sway bars?

Gville350

iTrader: (10)

Sway bars x1000 for actual functionality!

The brace is mainly for looks and for making sparks. LOL!

flowrider

iTrader: (9)

Search is your friend. Your question has been discussed many times.

Lou

hobie

Let me share my thoughts on this since i just installed it recently. I already have both sway bars and everything else is stock. The brace made the car feel tighter, more response, for some reason it feels like it has better traction now. Just pulling out of the drive way and turning to the street, i felt the difference. "Feel" is the keyword here. I'm not sure if this brace alone is going to decrease a lap time but the feeling i get when i drive the car now is worth the price. Hope that helps some what.

mjh09e

iTrader: (2)

Where did you get it and how much did you pay?

ohiois350

iTrader: (13)

i think you should get it, since Lexus made it to pair with the complete f-sport suspension, and swell sell them too, you only notice when you do fast and tight turn which i do all the time and love the feel of it

Kurtz

iTrader: (1)

Lexus also makes a $900 carbon fiber engine cover and sells that as an "F-sport" part too.

I've yet to see anyone, ever, show any measurable performance improvement from a brace like this... especially in street use on street tires.

If I were making a list of things that'd improve handling it'd look roughly like this:

F-sport sways
Better tires
Lighter wheels
Corner balanced coilovers lowered to a track-tested height


After you've done all that I'd still be surprised if adding the chassis brace did anything more than put dead weight on the car as far as actual performance, but it certainly won't make a measurable difference before doing all that.

Sffd103

iTrader: (16)

It's up to you if you want to spend the $300+ with Sewell discount. I like it. The sway bars are a must!

M32H32IS

I'm on the fence about this as well. Trying to get the same feel out of my IS as my M3 had in the twisties... Fwiw, the IS250 with full fsport package posted a higher slalom MPH and skid pad rating than an ISF (stock)

redspencer

iTrader: (1)

I too am going to add my 2 cents to this topic as I've been reading this debate over the F-Sport chassis brace for years on this forum and have been reading a lot of criticism from people that don't even have the part installed to give a true before and after opinion.

My IS350 had slowly gone through the full evolution of the F-Sport Suspension throughout the years (since 2008) and I can go to detail on my perceived feel of the vehicle through each iteration but that will be too long of a report. Essentially, my IS350 went through these F-Sport mod phases which I will use as a reference point:

Phase 0) Stock Suspension
Phase 1) Rear Sway Bar
Phase 2) Rear Sway Bar + F-Sport Shocks/Springs
Phase 3) Front and Rear Sway Bars + F-Sport Shocks/Springs
Phase 4) Rear Chassis Brace + Front and Rear Sway Bars + F-Sport Shocks/Springs

Slightly off-topic but since I have listed my 4 phases above, I'd like to provide my opinion on those that are on the fence on getting just the rear sway bar or both front and rear as a mod. When I was on Phase 2, I had all sorts of oversteering issues with the vehicle; when I went to Phase 3 and installed the Front Sway Bar to supplement the Rear, the car felt very neutral and all four tires had pretty much equal traction.

Back on topic. When I went from Phase 3 to 4 above, I immediately noticed that the rear chassis brace improved the polar moment of inertia and that the steering became immediately responsive to any rapid slalom type manuevers I performed on the road at speeds above 30 or 40mph. I still vividly remember the night I took the IS350 out for a test drive once the chassis brace was installed. The car felt 'twitchy' when I performed sharp turns or tested its center of gravity with slalom twists and turns. At first I didn't like the upgrade as I didn't feel as much in control with how responsive and immediate the car moved with only the slightest turn of the wheel but now that I'm used to it, I wouldn't go back to the looser feeling that the IS had previously.

Like Kurtz mentioned, I would ONLY install this rear chassis brace once you have done pretty much every other suspension mod to the car first (aka stickier tires, F&R sway bars, upgraded shocks/springs or adjustable coilovers, etc). I don't have first hand experience on this but I assume that the rear chassis brace would have negligible benefits if your still on a stock or mild suspension set-up.

I do autocross my IS and the car feels very planted with all the F-sport suspension mods installed. Maybe one day I can try a few laps with the OEM chassis brace and then swap to the F-Sport chassis brace to see if there would be a time difference (though the logistics in doing a chassis brace swap in the middle of a parking lot doesn't seem too viable ).

Jump2man3

iTrader: (7)

I Totally second what Hobie is saying. I just recently installed the brace myself. First I had the sways and just now the brace. I do admit the rear of my car feels tighter. I guess more stable....