It's kinda comical that they consider more front bias dangerous when the inverse is the truth...

(Front bias)^-1

For street use I'd say there's negligible uneven wear, as I've noticed on mine. I did however notice slight increase in front bias, but fitting rear pads with a little more bite took care of that.

Perhaps with regular track work you'll see accelerated uneven wear, but then flipping the pads from inside to outside should balance it out. Having said that, these brembo's aren't ideal for regular track work anyways.

My personal take... Mine were mounted upside down to keep the pistons correct, and I bled the calipers pointed up, unmounted.

I have been running Front and Rear 13' STI Brembos on my FRS. I started off running Stoptech Posi-quiets in the front and stoptech Street Performance in the rear.(because of the aforementioned bias from other people) I had no plans to track the car when I put the brakes on, and the pad choice reflects that.

I now have 5 track days on this setup. Off the bat I noticed more braking force and better pedal feel, however with that pad setup, I cooked them quickly. I could usually get 3 maybe 4 good laps until I had extreme fade. I only noticed the bias difference when braking hard and consistent from 100+. This setup for the street was perfect.

Last track day I switched out to Winmax W4's front and rear. I was running at Laguna Seca, which is notoriously hard on brakes. The brake bias difference was IMMENSE. I had tons and tons of braking power and consistency(which I attribute mostly to the pads)but the front was so much stronger that the rear would actually dance around on hard braking. I will be switching back to the stock rear setup soon, and test that as well.

I don't plan to have this setup for much longer, as I get more and more into tracking the car. It will be replaced with something actually designed for this car.

The second statement from the article about the piston size being incorrect for the FRS/BRZ is bullsh*t because the BRZ tS in Japan comes with the exact same Brembo set up as the WRX STI - 4 piston front, 2 piston rear - though I can't know for sure what the size of the pistons themselves are, IMO the possible difference could only be marginal.

The first statement does address the possibility of an issue if the staggered STI Brembos which in the past have used 46mm and 40mm pistons on the front caliper but again I think the size of the pistons and their positions is marginal - and I do believe that Subaru is reusing the same brembos for their WRX STI as the BRZ tS, I refuse to believe that they had a car specific brembo made for the tS but again I could be wrong about this.

Lastly, is there any validity to the statement about not being able to fully bleed out the caliper? I keep on thinking about how brakes are bled out and I don't really see how the air can't all be forced out.

Maybe,just maybe, it isn't so much as wanting to prove people wrong but to stop incorrect information being perpetuated.

In this case it would seem that there is negligible difference in having "incorrect" piston stagger but maybe with a different car fitting different model calipers would be disastrous. Where do you draw the line of when to correct?

Have you done the swap?

Now that I have more time...


1) After looking at pictures of split brembo calipers, the crossover indeed is above the bleeders.


2) This may or may not be a problem.


3) It still doesn't explain why there is a blocked bleeder fitting.


4) One could probably get around this by installing an external crossover.


5) Tapered pistons could be up there with crossdrilled rotors on the marketing scale. There's some that say it's bullshit in other words...


Anyway, until someone gets some measurements from the tS brakes, though jp says you have to run 18" wheels to clear them...

The calipers on the BRZ tS is identical to those found on other STi models, meaning they will 100% clear 17" wheels (with correct offset).

I'm no expert, but the posi-quiets wouldn't really be suitable on track. Perhaps keep the W4 rear pads but change to W2/3 fronts with better fluid, and give that a try before you swap back to stock rear calipers?

I have also purchased GDB Brembo calipers but I have not don't the swap.

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They aren't suitable at all for the track, that's why I removed them. I'm not really interested in band-aiding the bias issue. I'm running what is considered to be "great" fluid, and am not having any issues with fade or overheating, just bias. To be honest, the whole setup might come off a all at once if I can find something else I like.

I know stop tech changes the size of their Pistons for each kit. The same st-40 caliper for the sti, m3, vette and brz all have different sized front and rear Pistons. That is, inside the 4 pot caliper, the leading edge piston is a different size than the trailing edge for every model. If a small outfit like stoptech does this, I'm positive subaru, brembo and sti do this as well.

I don't doubt that some part numbers for some bbk's have different piston sizes depending on the application - the reason I said that I refuse to believe that they had a brembo made specifically for the tS is because some if not most of the parts on the BRZ tS were literally pulled out of bins and slapped on the car.

Unfortunately we'll never know for sure unless someone has the part number or measurements of the pistons for the tS brembos. :(