IS - 3rd Gen (2014-present) Discussion about the 2014+ model IS models

Best modifications to get increased handling / decrease body roll?

Old Jul 11, 2020 | 01:17 PM
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Default Best modifications to get increased handling / decrease body roll?

Right now I have springs and spacers but I feel like the car still isn't flat enough. I've driven a 2015 Porsche Boxster which felt like a go cart. I understand it's a Porsche and a mid engine sports car but I want to try to get close to that driving dynamic. I don't have rims, but would wider rims make help? Also should I look into getting a strut bar? Not sure what else to do.
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Old Jul 13, 2020 | 03:15 PM
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Upgraded sway bars really help. A stiffer rear sway bar on my 2IS was by far the single best improvement, cheap and installed in a few minutes. That was going to be the first thing I did to my 3IS, until I realized there is very little available due to the complexity and apparently a pretty involved installation. It really does suck the rear bar is so inaccessible.

Wider tires and strut tower bars will not really have any effect on body roll.
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Old Jul 13, 2020 | 05:55 PM
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Originally Posted by Tungstn-IS
Upgraded sway bars really help. A stiffer rear sway bar on my 2IS was by far the single best improvement, cheap and installed in a few minutes. That was going to be the first thing I did to my 3IS, until I realized there is very little available due to the complexity and apparently a pretty involved installation. It really does suck the rear bar is so inaccessible.

Wider tires and strut tower bars will not really have any effect on body roll.
Thanks for the insight, looks like there isn't much else to do
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Old Jul 14, 2020 | 02:12 PM
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Not much you can do. The rear sway bar (which I found out in 2016) requires lowering of the rear subframe. Doable but time consuming and expensive. You'd need an alignment after lowering the carrier.

Also your spacers like it or not have given you an effective lower spring rate making your car even mushier.

Truth of the matter is while the 3IS is a great handler for its class, it can't really be inherently or substantially better. Too much weight too high, and too heavy overall. Quite simply its as good as its ever going to get short of drastic weight reduction. The character is largely baked in, short of miniscule improvements you can make with big spending and a ton of downsides.

If you want affordable go cart handling, you're looking at an MX5.
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Old Jul 15, 2020 | 01:46 PM
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Originally Posted by E46CT
Not much you can do. The rear sway bar (which I found out in 2016) requires lowering of the rear subframe. Doable but time consuming and expensive. You'd need an alignment after lowering the carrier.

Also your spacers like it or not have given you an effective lower spring rate making your car even mushier.

Truth of the matter is while the 3IS is a great handler for its class, it can't really be inherently or substantially better. Too much weight too high, and too heavy overall. Quite simply its as good as its ever going to get short of drastic weight reduction. The character is largely baked in, short of miniscule improvements you can make with big spending and a ton of downsides.

If you want affordable go cart handling, you're looking at an MX5.
Thanks for the explanation. What exactly do you mean by 'mushier'? I thought spacers only affected the track of the car.. not the springs

Last edited by swaangin; Jul 15, 2020 at 01:57 PM.
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Old Jul 15, 2020 | 03:49 PM
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Originally Posted by E46CT
Not much you can do. The rear sway bar (which I found out in 2016) requires lowering of the rear subframe. Doable but time consuming and expensive. You'd need an alignment after lowering the carrier.

Also your spacers like it or not have given you an effective lower spring rate making your car even mushier.

Truth of the matter is while the 3IS is a great handler for its class, it can't really be inherently or substantially better. Too much weight too high, and too heavy overall. Quite simply its as good as its ever going to get short of drastic weight reduction. The character is largely baked in, short of miniscule improvements you can make with big spending and a ton of downsides.

If you want affordable go cart handling, you're looking at an MX5.
theres been a few posts on here about the rear sway bars, apparently by removing one of the rear suspension components the bar can me put into place and it’s about a 2 hour job, that’s from a guy nigeljdm that use to sell aftermarket ones. He said he put the instructions his social media but i couldn’t locate it. I’m curious how much a difference (if any) the RC350 rear sway will make.
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Old Jul 15, 2020 | 04:28 PM
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Thicker/stiffer sway bars are the most effective way to reduce body roll. How about adjustable swaybar endlinks to compensate for the lowering springs? With those, you can also try to preload the sway bar to get a slight stiffening effect but you can at least play around with a few options.

Also dont overlook tires, get a stiffer XL sidewall if they have one in your size. If you can run summer tires, Michelin PS4S are your best bet for a wet/dry summer tire.
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Old Jul 16, 2020 | 12:55 PM
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Originally Posted by NickCaesar
theres been a few posts on here about the rear sway bars, apparently by removing one of the rear suspension components the bar can me put into place and it’s about a 2 hour job, that’s from a guy nigeljdm that use to sell aftermarket ones. He said he put the instructions his social media but i couldn’t locate it. I’m curious how much a difference (if any) the RC350 rear sway will make.
He's probably talking about undoing the large fasteners and drooping the rear axle carrier. doable but you'd still want an alignment.

it should make a nice difference.

as far as "what do you mean by mushier," well any time you extend your wheels, they act as a longer lever doing more work on the spring with less work, effectively decreasing your spring rates. (and damping rates for that matter). Imagine trying to undo a really stubborn bolt with a 1 foot bar. Now imagine how much easier it is with a 2 foot bar. There's more acting force. the amounts are exaggerated to make a point.

spacers are a compromise when your suspension is not designed for it. and that's fine so long as you are ok with that compromise. usually it's fine for a street car. but if handling is your ultimate concern, then the spacers are detrimental.

it's small, but a difference nonetheless.
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Old Jul 16, 2020 | 02:42 PM
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There is a way to do it by only undoing one side of the rear suspension. I never did find the instructions.
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Old Jul 16, 2020 | 03:11 PM
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Originally Posted by JGO
There is a way to do it by only undoing one side of the rear suspension. I never did find the instructions.
Same. I’m assuming a mechanic looking at the bar and the rear of the car could probably figure it out. I’m going to get a price for the bar next week and see if my mechanic wants to take the job on.
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