will the sti brembos fit fr-s/brz?

[Dave-ROR]

Originally Posted by old greg

It's the other way around actually. There's more pressure/wear on the leading edge of the pad, so a proportionally larger trailing piston helps keep heat and wear evenly distributed across the pad face under hard braking.

Doh sorry about that. You are correct. I'm confusing myself lately lol

[JRitt]

Dave-ROR is correct. Also, the piston bore sizes are likely not optimized for the proper brake bias/balance on the BRZ. The items that can alter the bias are disc diameter, piston bore size, and brake pad coefficient of friction (mu). All of the below items assume that you don't want to change your brake master cylinder (which 98% of the people reading this likely have no desire to do).

1. The STI brake disc is either 325mm diameter. I believe the OEM BRZ disc is 299mm diameter? If you held everything else constant on the car and just increased the front disc diameter, you'd shift brake bias towards the front of the car.
2. I can't remember the piston area on the STI off the top of my head, but it is likely larger than the piston area on the OEM BRZ calipers. That would further amplify the brake bias towards the front.
3. Now if you add a larger rear disc and larger rear caliper piston area from the STI Brembo's, you can shift some bias back to the rear. That said, to be optimized for the BRZ, the front increase in brake torque and rear increase in brake torque would have to be in the same proportion to keep the overall balance the same as the OEM setup. That is possible, but likely not the case.

The results of improper bias: All four tires are likely not sharing the proper amount of work. In most of these cases, the car is front biased, which means the rear tires aren't being used to their full capacity to stop the car...resulting in longer stopping distances than stock. Also, you run the risk of having ABS problems, or premature intervention. Finally, if the overall piston bores in the calipers are substantially larger than stock, you will be displacing a lot more brake fluid into those calipers. That can mean that your brake pedal travel will be longer.

That is all in addition to the differential piston bore issues that Dave mentioned above.

In summary...upgrading to Brembo's from another platform such as an STI, Evo, or 350Z would a cosmetic upgrade only. The brakes would look better, but that's about it. Your actual performance would likely be worse...and possibly be much worse. Longer stopping distances, longer pedal travel, potential ABS issues, pad taper because of the 'upside down' calipers, etc. So if you want your car to look good parked, putting OEM calipers from another application is a good solution. If you want it to have the best braking performance possible...not so much.

All of these factors need to be considered when you design an aftermarket brake system upgrade to work with the OEM master cylinder. The proper disc size, piston bores, and piston stagger all need to be calculated to achieve proper brake bias and performance.

Hopefully that helps.

[JRitt]

One more thing I forgot to add...the cost of doing a "homebrew" brake upgrade using components from other OEM platforms typically adds up to what it would cost to buy a fully thought-out system from one of the aftermarket suppliers. In many cases, people have to fabricate or modify parts, purchase additional bits they didn't realize they need, etc. When it's all said and done, they have a sub-par performing system that costs about the same as an optimized aftermarket system. They also typically have spent a lot of time and frustration getting things sorted. I've seen it happen a million times over the past 9 years that I've been working in the aftermarket brake business (for full disclosure, I was Sales Mgr. at StopTech for nearly 5 years, and I now represent AP Racing in the USA).

[eikond]

Great posts JRitt! Thanks for sharing your knowledge!

What is your expert opionion on slotted and/or drilled rotors? I'm sure there will be a ton of cheap or expensive replacement rotors hitting the market soon. Are they a worthwhile upgrade? Do they help disburse heat as advertised? Do they warp much more quickly than uncut blanks? I know they are a little hard on pads..

I'll admit that I'm not planning to race the car regularly.. maybe a few SCCA events at most. I will also admit that I really like the appearance of the drilled rotors.. So I'm guilty of wanting the "bling" in this instance.

Just curious what your thoughts are..

[Racecomp Engineering]

JRitt knows his brakes.

I think we'll see a lot of the STI "upgrade" but it is not necessarily a solution I would recommend at this point.

- Andrew

[Turbowned]

JRitt, I understand where you're coming from for the most part, but couldn't some of those potential issues be remedied with a larger bore brake master cylinder (from an STi perhaps) and an adjustable proportioning valve? I still see the potential for ABS issues with this, I know.

Apparently GReddy did this "upgrade" on their FR-S, with separate rear calipers for hydraulic e-brake. How would they bleed the calipers if the bleeder screws were at the bottom of the caliper - pressure bleeder? Considering they're running these brakes on their 600hp drift FR-S, I'm inclined to believe they work - at least somewhat! I sent them a Facebook message asking if they could shed some light on the subject.



Again, I still find the '06-07 WRX calipers to be a more attractive option, but no doubt a lot of people will want to try the Brembos, and it would be nice to get all the facts straight for them.

[Dave-ROR]

Originally Posted by eikond

Great posts JRitt! Thanks for sharing your knowledge!

What is your expert opionion on slotted and/or drilled rotors? I'm sure there will be a ton of cheap or expensive replacement rotors hitting the market soon. Are they a worthwhile upgrade? Do they help disburse heat as advertised? Do they warp much more quickly than uncut blanks? I know they are a little hard on pads..

I'll admit that I'm not planning to race the car regularly.. maybe a few SCCA events at most. I will also admit that I really like the appearance of the drilled rotors.. So I'm guilty of wanting the "bling" in this instance.

Just curious what your thoughts are..

Slotted have their place. Drilled blanks have their place too, show cars and the trash can. Rotors cast with holes are better, but most still replace them with blanks for track use. Dimpled rotors I haven't used (cast with "holes" that don't go all the way through).

The rotor has multiple jobs. One of those jobs is to remove heat from the caliper/pad. In other words, one of it's jobs is to be a heatsink. As with any heatsink, mass is critical. Removing metal from a rotor means less mass, which in turn means the rotor can't remove and hold as much heat. This is why PROPER brake cooling actually cools the rotors (and sometimes the rotors and calipers). Just cooling the calipers should only be done when it's not feasible/possible to send the cold air to the center of the rotor (assuming ventilated rotors).

For the street/autox you should not be building up enough heat to really make a cross drilled rotor show it's inherit problems though (cracking/higher potential catastophic failure) so just keep an eye on them.

[Dave-ROR]

Originally Posted by JRitt

One more thing I forgot to add...the cost of doing a "homebrew" brake upgrade using components from other OEM platforms typically adds up to what it would cost to buy a fully thought-out system from one of the aftermarket suppliers. In many cases, people have to fabricate or modify parts, purchase additional bits they didn't realize they need, etc. When it's all said and done, they have a sub-par performing system that costs about the same as an optimized aftermarket system. They also typically have spent a lot of time and frustration getting things sorted. I've seen it happen a million times over the past 9 years that I've been working in the aftermarket brake business (for full disclosure, I was Sales Mgr. at StopTech for nearly 5 years, and I now represent AP Racing in the USA).

Looking forward to seeing what you guys come up with for this car.

[Turbowned]

I find it rather silly that Porsche and others still use cross-drilled rotors these days. A drilled/slotted rotor may weigh less, but there is also less rotor surface for the pad to bite down on. Since most pad compounds don't produce the gases they used to, it is my understanding that drilled/slotted rotors are functioning strictly for looks because the holes aren't needed to dissipate gases. The worst part is that when you replace pads, you can't machine the rotors on a lathe so they usually have to be replaced, too.

[Dave-ROR]

Originally Posted by Turbowned

JRitt, I understand where you're coming from for the most part, but couldn't some of those potential issues be remedied with a larger bore brake master cylinder (from an STi perhaps) and an adjustable proportioning valve? I still see the potential for ABS issues with this, I know.

Yes, but how many people will do that? JRitt comes from a similar car background (not in terms of work, but we've owned the same car and have seem some of the same stuff) as I do so we've both see what some people have done in the name of "brake upgrades". Even companies don't always do this stuff correctly, I remember when AEM released their BBK for Hondas and increased stopping distances due to the very things being discussed in this and previous brake discussions so expecting your "average joe" with no track/race experience to understand enough to diagnose and come up with a solution for these problems isn't something I'd bet on. JRitt and I talked about brakes on this car months ago and the MC and brake bias were some of the first things discussed but I wouldn't expect most people to go there. For minor bias differences just pads can fix it too, but that's a band aid IMO (not that I haven't used that bandaid..).

Apparently GReddy did this "upgrade" on their FR-S, with separate rear calipers for hydraulic e-brake. How would they bleed the calipers if the bleeder screws were at the bottom of the caliper - pressure bleeder? Considering they're running these brakes on their 600hp drift FR-S, I'm inclined to believe they work - at least somewhat! I sent them a Facebook message asking if they could shed some light on the subject.

Even with 600HP the amount of braking that car does isn't all that high. It's not seeing 45 minute hot sessions on the track, or more. We also don't know exactly what they've done, have they replaced the MC, prop, retapped the caliper to put a bleeder up top, etc.

From a cost perspective, IMO, the STI "upgrade" is simply NOT worth it. I priced it all out in threads months ago, and it just wasn't worth it to do it as correctly as possible.. and 04 STI blanks are expensive so consumables would be high.

As for bleeding, they could just have the calipers on the opposite sides, differential bore problems, but they'd bleed correctly. If you have the patience you can unmount them, flip them, and maybe get them sitting back on the rotor enough to bleed. I wouldn't deal with it myself, I'd rather just get something that's proper.

Again, I still find the '06-07 WRX calipers to be a more attractive option, but no doubt a lot of people will want to try the Brembos, and it would be nice to get all the facts straight for them.

If you want 4 pots, I'd agree. Again though, if everything else is equal including the functionality of the 4 pot WRX caliper, you won't change anything but looks, modulation/brake feel and a slight difference in pad wear.

In the end, it all depends on what your needs/reasons for replacing the brake components are. If you just care about looks, then the STI brembos work. If you care about street use mostly, the WRX 4 pots and STI brembos would "work", with the caveat that braking performance is likely to suffer so that drunk driver that was avoidable with the stock brakes may result in a crash. For track use, stock with cooling, good pads and lines, and if your needs exceed that setup, a properly engineered system would do the trick.

[Godzpeed]

I'm sure STI engineers would put stuff that "doesn't work" on their cars.....



seriously, how much on hand experience did you have with aftermarket and retro fitting braking systems??

[OrbitalEllipses]

There's no evidence that the brakes on the STI concept aren't from the Impreza WRX STI. It's a show car meant to showcase possible product development, not a full-blown race car or a street car that needs to function 100%. Read what Dave-ROR and JRitt have been saying; I expect people asking about the STI Brembo swap in the future to be banned as this information has been discussed to death.

@Turbowned: Was it necessary to come into another thread, spew more propaganda about magazines (saying the wrong things), more about GReddy, and continue to ask the same questions which were previously answered in other threads (WRX 4pots)?

[Turbowned]

Originally Posted by OrbitalEllipses

@Turbowned: Was it necessary to come into another thread, spew more propaganda about magazines (saying the wrong things), more about GReddy, and continue to ask the same questions which were previously answered in other threads (WRX 4pots)?

*shakes head* Yes, it was, as I am trying to get to the truth. Is it necessary for you to get your panties in a bunch every time someone asks a question or makes a small error? Probably not. Please don't make this like the "Do a search n00b WTF amirite" Honduh forums. Moto-IQ is one of the few sources out there that takes the time to look into all the gritty technical details of cars, and includes the best and brightest in the industry, so I tend to trust them; You just let me know when you know more about cars then they do.

Dave-ROR and JRitt, thanks for the insight! I agree that the average enthusiast isn't going to think about upgrading the BMC or adding a prop valve, and you're definitely right about the cost vs. benefit with these brakes. You're also right about the drift car not needing serious braking effort out there on the track; that had occurred to me as well - I think the e-brake is the only thing on that car taking serious abuse It looks like as far as the bleeding was concerned, they may have drilled and tapped the opposite end of the caliper for a bleeder screw, and put a pipe plug where the original screw was. Definitely not something Joe enthusiast would do, either. I would still like to hear from GReddy as to what their exact process for installing the brakes was, and what results they've had from using them. No doubt it's not a good swap for the average enthusiast to attempt, but there's a difference between "it's not the best idea" and "it can't be done".

[Dave-ROR]

Originally Posted by Turbowned

but there's a difference between "it's not the best idea" and "it can't be done".

Absolutely. I never actually intended to say that it couldn't be done so I apologize if I did state that. We've had so many of these STI brake discussions that I can't recall the details of them all now but I never believed it was impossible, just not really ideal