My wheels just barely fit the F Sport brakes as well and with the new RCF calipers, I ordered a 20mm spacer.
I think 10mm would work but i can't find one and don't feel like knocking out studs and doing the over-sized ones. Hopefully that 20mm will be ok with the look of the wheel verses the fender line.

My rear wheel barely fit, super close to the face of the caliper.
You have to cut your dust shield to allow rear caliper to bolt up. I haven't removed / disconnected old calipers/lined yet cause I forgot to get brake fluid, thought I had an un-opened bottle on my shelf.
Figured I will get everything bolted on and then do the lines later today or tomorrow.

Here are the pics.

Front



Rear
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Did you happen to look into if the GSF/RCF backing plates would bolt up to the IS? I'm a big fan of the "is that OEM" look when you can't tell if the car came with something or not cause it fit so perfect.

The brakes look awesome btw...the backing plates would have been the cherry on the orange cake.

 

Thanks,
I am the same way, I like to have that factory look too.

Front backing plates do not. The knuckle is different. The RCF/GSF front backing plates bolt separately than with the HUB. The IS backing plate is between HUB and Knuckle.

Rear backing plate, you will have to pull the axle and HUB from the knuckle, real pain in the ***. Only thing I don't know if the HUB has same bolt pattern between IS and RCF.
Would have to buy them and compare. The adapter plates do relocate the calipers up a little. so if you are to change the backing plate it might be an issue.

I did a pretty good job on cutting the backing plate, used my cutting wheel, angle die-grinder to sanded and cookie disc it. and threw on a coat of matt-black paint and heat gun it to bake it on.
In a 1.5 years after warranty is up I will be trading it in for a new one. Better believe I will be using these calipers on the new one.

 

Is that too close? I measured 2 mm.
I don't want to bring the wheel out I already feel as it is out enough.

 

do all 4x Tires spin properly by hand?...i would do this before driving on them as it could scrape/scuff the Caliper if it hits


they look awesome!...good stuff

 

If you have legit 2mm of clearance, then that's more than enough. Even with heat expansion and cornering, it won't rub.
My front wheels had 1mm of clearance to the caliper, never touched.

 

What's your wheels size and width and offset ??

Looks nice I just ordered mine thanks for all the information

 

Thanks, they spin by hand, just worry about any flexing cause the tolerances are so close. It wouldn't be good when driving on the highway and they meet.

I'm really hoping they work out. LOL


Yeah I would like to see how they look on yours. What color are you going with, Black Blue or Orange?

I ordered them from an online wheel shop for the vehicle specific, (19" stagger I don't know the offset) I really wish instead of ordering them for an IS series, I went with the RC F one, I didn't even think about these brakes yet. Now I have to use spacers and I hate spacers.
As you see they just barely fit the rears, but they cannot clear the front of the front calipers.

I am getting a 20mm spacer coming today from amazon. will test, if too much I will also try a 15mm on Monday and if i still have room, I am going to get extended lugs and do a 10mm.
Basically I am just throwing money at this, so if you haven't ordered the wheels get the RC F measurements especially with these brakes, it's not so much the diameter but the amount the calipers stick out.

 

You're tire limited, not brake limited for a one time stopping event.

May want to confirm the master cylinder bores did not change based on vehicle. Also a question of if the ABS module has variation to support different F:R balance (due to different effective brake radius differences and possible piston area differences).

Point being, bigger isn't necessarily better or stops more effectively in a single event panic stop situation.

 

Gotta have to go with Hardrvin on this one since he brought it up.
For all the big brake upgrades out there, i.e. RCF/GSF, RR Racing, etc., they only supply the components at the wheel...rotors, pads, calipers, brackets, brake lines...but what about the Master Cylinder??
The reality is the Master Cylinder can only push so much fluid and force based on it's design. While it's true that increasing the rotor/pad surface will give you a little better braking, there's no way that anyone is maximizing these BBK's.
I get that most do it for looks, and that's fine, hell I upgraded my IS250 front brakes to the 350 ones...but to that point, the 250 and 350 of my year have the same Master cylinder, so I am maximizing the braking for the front brakes based on the design of the Master.

I can't imagine the RCF/GSF have the same Master as the IS, so to really maximize the braking power, the Master would be needed that matches the brakes.
Don't get me wrong, the IS will still stop better with just the BBK and no Master, but it's just not going to stop as good as it can if it had the proper Master Cylinder installed...however, at that point it might be too much brakes for the IS...maybe.

Imagine fitting the RCF/GSF brakes on a Toyota Yaris...the car might not even stop because the Master can't generate enough force to clamp those massive calipers LOL!!!

 

Is it 19" 8 or 8.5 or 9 or 9.5 ??

Because I have the front wheel is 19" 8.5

And want to make sure

 

8.5 front 9.5 rear

 

Yep of course it all has to be balanced out. But I'll still get better braking with larger calipers. I might even look at getting a RCF master and change it. Will continue to make it better.

 

 

Looking good!