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Rear chassis member brace

15K views 26 replies 10 participants last post by  rijn_in 
#1 ·
I have a 2011 IS 350 F Sport on the way and am looking for opinions on F sport suspension mods. I am wondering if I should get the rear chassis brace or the front and rear sway bars, or both! Opinions? Im not a gear head but love agressive driving.

Thanks!!
 
#3 ·
Funny, the braces do more than you think. I don't know how many customers of mine love the fact that their sunroof stops making noise now and their exhaust doesn't hit when backing out of a driveway.

D
 
#5 ·
I have a hitch installed onto my car for transporting bicycles. Do you think the f-sport chassis brace offers any advantage in this situation? I'm assuming it would help reduce the chassis twisting caused by wind drag or an evasive turn with a bicycle. I use the vehicle for road trips (8-9 drives) transporting the bicycle.
 
#12 ·
Knightshade has saved me $375 plus install as I was about to buy this thing. Not to create any sore feelings here, however, APynckel seems to be a believer in the mod. while Knightshade reasoning seem sound to me I would be interested in knowing why Apynckel disagrees (if that is indeed the case).

I have a 350 F Sport with front/rear sways and a new set of Hankooks. The F Sport already has lowering springs and stiffer shocks, however, I'd still like to stiffen up the handling aspects of this car.

My other car is a Cayman S so I guess I've set the bar fairly high in the handling department. That's why I was interested in the brace. Plus, I'd want to keep the car stock.

I appreciate/respect all opinions. I know crap all about cars other than which ones I like.
 
#13 · (Edited)
Because rigidity of a chassis and the harmonics of a chassis are not the same thing.

Anyone who denies outright the beneficial aspects of a structural piece that more firmly ties together opposing sides of a vehicle (which would otherwise only be connected by an arch over a driveshaft) with a space truss, is not very well informed in the fields of structures or harmonics. There is flex that would be negated with this brace in place, and the overall harmonics of the car would be changed. Whether that's for the better, Lexus should test and release data (since they decided to release this part as an "upgrade").
 
#14 ·
The fact they have offered no such data kinda supports my point it's a useless upgrade though.

Because it is.

Likewise throwing bigger brakes on a street car is a useless upgrade, despite the "theoretical" things bigger brakes can do. Because you're limited by the traction of your tires, which even the stock brakes are more than adequate for.

Just as in this case your handling won't improve, at all, by making the chassis stiffer because chassis flex isn't currently holding back handling at all.

Note I didn't say the brace didn't make the car stiffer, which you seem to be assuming. I said it was useless. Because the added stiffness doesn't make the car handle any better.

It's kind of like if you're building a building... your plans call for it to be able to withstand a 5.0 earthquake... you can spend a ton of money and make it more "structurally sound" to stand up to an 8.0... but if the strongest quake that has ever, or likely will ever, hit the building is a 3.0... that's a stupid waste of money. Doesn't mean the extra money won't make the building "stronger" but it's pointless to do it. Same thing here with making a chassis (where flex doesn't limit you in any way) flex less.

It's possible there'll be a subjective 'feel' difference (just as changing your brake pads can cause a 'feel' difference, but make absolutely no difference to the distance the car actually stops in)...Indeed the several threads from folks who have done this mod have varied from no-difference period to there's a (very small) feel difference, but nobody has observed any measurable improvement in anything.... and that's not really worth throwing an otherwise useless hunk of extra metal on the car IMHO.
 
#20 ·
I happened to look under the car. It comes from the factory with a chassis brace and was told the f-sport brace weighs around 10 pounds. I'm going to have the f-sport brace installed and will let you know if it helps. I doubt the weight penalty will be that severe since it will replace the stock brace.
 
#22 ·
I realize this might not be my "place," given that I'm a first-gen owner, but too bad ;)

In general terms, adding one brace here or one brace there won't make a night and day difference. Braces should work in tandem with each other, with an overall goal of improvement. People that say braces made a significant difference are usually the ones who have braces strategically placed so that they compliment each other.
 
#27 ·
I've had the car back for a few days. The chassis brace is well worth the purchase. Corning at low or hight speeds is a joy in this car now. Its feels stable and planted to the road. Going fast is great, but taking a turns slow or fast is more enjoyable.

Which strut tower brace is recommended?
 
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