The durometer rating of the rubber is the only difference. I'm not sure what the actual number is for each, but the RCF ones are obviously stiffer.

 

Hey ! In a short time, we should know if the tirewear problem was fixed on 2021 isn't it ?

 

This seems doubtful, but yeah, I suppose 2022-2023 we should start hearing about tire wear if it's still an issue on the '21 models.

 

I called the Service Manager at my local dealership to ask if he knew. Don't kill the messenger; here is what he said:
* The IS tire wear issue is by design where they camber to help cornering
* He is familiar with the forum and the claim it's the bushings; he was quite adamant
* His fleet loaner only has 3k miles so he doesn't have definitive understanding if it's been fixed
* From the front of the car, can see the alignment difference between 2021 vs previous years so he believes the tire wear issue is a thing of past

We shall see, I suppose. I may call the other dealer's service dept to see what they say.

 

I'd believe it was the camber if our front camber actually was aggressive. It's very mild. Our rear tires have a lot more negative camber and yet experience no inner wear.

 

Received my Front RCF LCA bushings from MegaZip today. Ordered Thursday, received Wed. Ordered SPC rear Camber arms for rear from Amazon on Friday, received Sat. I will be installing tomorrow or Friday. Thanks for all the info guys! I would say I am a fairly aggressive driver. Any suggestions on my alignment settings?

 

If the car isn't lowered then you won't need the SPC camber arms.
If the car is lowered, then install the LCA bushings and SPC arms and set the alignment to factory specs....or best you can...depending on how low you are the front it may never be within spec.

In terms of setting up the alignment for aggressive driving, the LCA bushings and SPC camber arms are used to avoid excessive tire wear...you could set the alignment up for better cornering, but that pretty much would counteract everything the LCA bushings and SPC camber arms are trying to accomplish...at that point you might as well leave out the SPC camber arms. The LCA bushings will help regardless of high and driving style.

 

I had pretty bad inner wear on the fronts as well as the rears. I have a print off of what my alignment before correcting. Hopefully I can upload it here.

Thanks again for all the responses.


Current Alignment before front LCA RCF bushings.

 

Not sure which way to go....

FIGS
RR Racing
GSF/RCF

RCF seems to be the cheapest way to go, but it seems like FIGS is the better option.

 

Based on the alignment specs all you need is a front and rear Toe adjustment...the right rear Toe is actually spot on. so that doesn't need adjusting.
The left rear Toe would be adjusted to the same spec as the right thus zeroing out the Thrust Angle.
Of course after that the front Toe would need adjustment. The rear has to be done first as it will directly effect the front alignment.
Other than I say throw in the RCF bushings and you should be good to go.

 

You recommend the rear toe to be at 0.1? Got mine done at 0.015 lol

 

Big thanks to the forum, had my Figs LCA Bushings installed Monday, and oh my god.
Steering is so solid now, and everything feels so much tighter.
Can't recommend this upgrade enough.

 

How much more harsh does the car drive now? That's the only downside for me. Is there a sizeable difference in that aspect?

Does anyone know the durometer of the OEM bushings on the 3IS?

 

I've got the 90 duro installed, they also sell an 80 duro on their site.
I wouldn't call it sizeable, the roads here are bad already so there wasn't a noticeable difference to me. The steering translates more of the road, but I wouldn't necessarily call it rough if that makes sense. Still rides smooooth. If anything, the ride is smoother due to the more accurate steering in turns etc.
On good roads, I can't tell the difference, on bad roads it was already bad anyway so no big loss there.
​​​​​And the most important? My gf said she can't feel a difference in the passenger seat. That's an endorsement if I ever heard one.

 

So just to be clear, the RC F bushing will fit on the 2021 IS350? I know they worked on the 2020 model but just wanted to be clear for this MY, which I am pretty sure would work but wanted to double check - Thanks in advance for the input