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I wanted to share my brake upgrade, and is pretty much just a combination of two well-known kits that I have not seen used together and those are the Arizona Performance 6 piston front kit with the Evo/STI rear kit.

My motivation for this kit was to find a really good weekend warrior brake kit that was somewhere in between the currently available kits. I feel there are great options on either end of the spectrum but not a whole lot in the middle with great street performance and the ability to do really well on the track. Also worth noting that I wanted something fairly easy to install because I did not feel comfortable trying a one off custom set up.

There are a couple of big brake kit options available that are completely drool worthy, but for me I just could not justify that kind of money. These also left me wondering whether or not I really needed that kind of stopping power or if its overkill for my application.

The cobra and Mercedes fronts that are great budget buys but are ultimately just stock systems for other cars retrofitted and I wanted something a bit more race inspired.

One of my big concerns was keeping as much of the stock ratios and as close to what the Toyota engineers intended, so any upgrade I wanted to be achieved as evenly as possible.

Bias: I was able to calculate brake bias by using this calculator posted by sixpack years ago. With the specs of the stock system I was showing a front brake bias of .708 percent, and a front brake bias of .698 for this kit. That is within a percent of the stock system.

StockNew
Leg input in pounds:
60​
60​
Master cylinder diameter:
1​
1​
Front line PSI (un boosted):
509.296​
509.296​
Front caliper pist dia 1:
2.36​
1.62​
Front caliper pist dia 2:
1.1225​
Front caliper pist dia 3:
1.1225​
Total front piston area:
4.374​
4.04​
Front pad Cf:
0.4​
0.4​
Front rotor diameter:
11.89​
13.06​
Front pad radial height:
2.2​
2.43​
Front Rotor Torque In.lbs.:
4317.554​
4374.808​
Rear line PSI (un boosted):
509.296​
509.296​
Rear caliper pist dia 1:
1.5​
1.575​
Total rear piston area:
1.767​
1.948​
Rear pad Cf:
0.4​
0.4​
Rear rotor diameter:
11.45​
12.44​
Rear pad radial height:
1.665​
2.36​
Rear rotor torque In. lbs.:
1761.3​
2000.376​
Percentage of front Bias:
0.708​
0.698​

Bias Calculator

Rotor: The main benefits of any rotor upgrade is going to be size for thermal mass here is a quick break down of the rotor sizes with the front getting a slightly bigger upgrade because it bears roughly 70 percent of the stopping force.

The Wilwood front rotors get some awesome upgrades in addition to what is visible in the calculator above, two piece construction and being 1.25 inch thick compared to the .787 of stock. The rear rotor keeps a fully functioning stock e-brake.

OldNewIncreasePercent
Front Rotor11.8913.061.179.84
Rear Rotor11.4512.440.998.65

Weight: Some big brake kits can weigh significantly more than the original equipment. I thought it would be interesting to weigh all of the components, and this kit is actually marginally lighter than stock.

OldNewTotal
Front Caliper
12.8​
8.8​
-4​
Front Rotor
14.8​
17.2​
2.4​
Rear Caliper
8.4​
4.6​
-3.8​
Rear Rotor
11.6​
16.8​
5.2​
PerSide
-0.2​
Total
-0.4​

Calipers: These calipers move to a dual piston setup instead of the clamp. The front calipers increases from a single piston to 6 piston with the rears going from a single to 2 piston. The Wilwood FSL6R are also radial mount, forged, with staggered bore which are all added bonuses at this price point.

Cost: In total this kit was around $2,600, but as shown below I spent quite a bit more than required between powder coating calipers for color, buying new parts instead of in spec used, and upgraded fasteners. You could easily knock about $500 off this without doing these upgrades.

Arizona Performance Front Wilwood BBK- $1,745
Wilwood FSLR6 6 Piston Radial Mount Brake Calipers
Wilwood 13.06" 1.38" Spec 37 Rotors
Wilwood Standard BP-10 Pads
Braided Lines
Brembo STI/Evo Rear BBK
Brembo 2005 Evo 8 Rear Calipers $250
Rebuild and Powdercoat $200
StopTech Slotted Kryo Rotors 2005 STI $260
Machine Work 60.15mm Hub $30
StopTech Sport Performance Pads $65
Arp Chromoly Bolts 662-1005 $17

Full discloser I am far from and expert but I have definitely enjoyed learning as much as I can though this process. I would love to hear people’s thoughts good or bad on this setup. Hopefully this helps people in a similar situation and doesn’t have any major pitfalls that I missed.
 

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Looking forward to your future review of this kit. I was looking at the Arizona Performance kit, but didn't want to have to spend $200+ per rotor when doing replacements.
 

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YotaMD.com author
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724 Posts
Very cool to see all the tech info broken down like this. I am looking to do an ARZ kit on my mk3. I'm planning the front and rears, but those ARZ rears are EXPENSIVE. I'm anxious to see what you think of the end result of yours.
 

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but those ARZ rears are EXPENSIVE.
There's a not-insubstantial amount of machine work that goes into just the hub for using the OEM parking brake. The quality of work is totally worth it though. I imagine for 90% of the BBK buying crowd the setup OP has is more than sufficient. With the same 6 piston setup OP has and the OEM rears I was never able to get measurable brake fade on the local track that tends to be heavy on the braking for the faster/heavier cars.

Unless you're OCD like me the Brembo rear setup is a great compromise to the $1600 rear kit.

but didn't want to have to spend $200+ per rotor when doing replacements.
These rotors last a long time, but yeah, they're expensive. The rotors from everyone but ARZ won't have the black E-coat either so if you want that you'd have to get replacements from ARZ.
 

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YotaMD.com author
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There's a not-insubstantial amount of machine work that goes into just the hub for using the OEM parking brake. The quality of work is totally worth it though. I imagine for 90% of the BBK buying crowd the setup OP has is more than sufficient. With the same 6 piston setup OP has and the OEM rears I was never able to get measurable brake fade on the local track that tends to be heavy on the braking for the faster/heavier cars.

Unless you're OCD like me the Brembo rear setup is a great compromise to the $1600 rear kit.



These rotors last a long time, but yeah, they're expensive. The rotors from everyone but ARZ won't have the black E-coat either so if you want that you'd have to get replacements from ARZ.
Oh I don't doubt it.

I am still eyeing the nice rear ARZ kit as my top pick. Didn't mean to insinuate they wouldn't be worth it. The only reason I have fun money to buy brakes in the first place is because I make and sell top tier (boutique, maybe) products so I'm all about making the best out there and charging appropriately. Especially if it supports another niche small business.

I actually thought the rears where more than $1600. Looks like there's a $1900 option for the drift series, but that's the top. You know you've been looking at too many expensive car parts when $1600 seems quite reasonable, haha.
 

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Didn't mean to insinuate they wouldn't be worth it.
Didn't think you were at all, just figured you were like me initially thinking "holy hell that parking brake is pricey". Also figured if anyone else here could figure the value of the ARZ kits it would be you.

You know you've been looking at too many expensive car parts when $1600 seems quite reasonable, haha.
Once upon a time I scoffed at buying a $900 set of pistons. Now? "It's only $1600? Lets add some more options to those" Turbo? "Yeah, that'll be 3 months worth of mortgage payments, got any add on options available?"

Weight: Some big brake kits can weigh significantly more than the original equipment. I thought it would be interesting to weigh all of the components, and this kit is actually marginally lighter than stock
Out of curiosity I did a quick number crunch on rotational mass change on the front kit and it came out pretty much even with the overall weight decrease. Don't remember the numbers off the top of my head but I want to say it was around a pound less than OEM all said and done. So not only do you get better braking but you get a small decrease in the amount of weight you have to get spinning too.
 

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YotaMD.com author
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Out of curiosity I did a quick number crunch on rotational mass change on the front kit and it came out pretty much even with the overall weight decrease. Don't remember the numbers off the top of my head but I want to say it was around a pound less than OEM all said and done. So not only do you get better braking but you get a small decrease in the amount of weight you have to get spinning too.
But did the moment of inertia increase due some of the mass now living further from the center axis?
 

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It did, but I stopped about halfway through that math because that's hard as shit.
I recall a magazine or website 5-10 years ago ran a test like that and found a significant drop in horsepower after installing a big brake kit. I recall it being 10+ hp on an AWD car. The assembly was lighter, but it was a net increase in inertia between the larger diameter (but lighter) wheels and larger diameter (but lighter) brake discs.
 

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Do you see any issues later down the road with those willwood pistons having no dust/moisture boots?

I've always been curious to see how long that area stays clean / functional on a street driven vehicle using race style calipers.
 

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I recall a magazine or website 5-10 years ago ran a test like that and found a significant drop in horsepower after installing a big brake kit. I recall it being 10+ hp on an AWD car. The assembly was lighter, but it was a net increase in inertia between the larger diameter (but lighter) wheels and larger diameter (but lighter) brake discs.
The wheels are going to account for the majority of the increase there.

Wilwood 13.06" rotors have a total rotational inertia of .152 kg-m2 (that's meters squared, apparently we can't superscript here)
That's .031lb-ft2 (feet squared)
Or 2.15PSI

OEM 11.89" rotor have a total rotational inertia of .116 kg-m2
Or .023lb-ft2
Or 1.59PSI

So we have an approximate difference of .56PSI of pressure required to spin the larger Wilwood rotors over the OEM. There's at least a couple of chapters of grad school level physics (probably engineering too) involved in converting all that to something comparable to HP of Lb/Ft torque. I am definitely not that smart and even if I was we've already hi-jacked OPs thread. And my head already hurts.

Do you see any issues later down the road with those willwood pistons having no dust/moisture boots?
I've never seen or heard of any issues with it but with Wilwood going back and redesigning calipers to incorporate dust seals I imagine there is some evidence out there of wear caused by either dust or moisture.

But looking at OPs caliper it appears to be the new version with the dust seals.
 

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Oh nice!
I was not aware they starting adding external seals to the pistons.
Good move IMO.
Yep, they started a while back with the Aero 6 caliper and started cascading to the rest of their calipers from there. I don't really have a time frame as to what model got them when but Wilwoods site will update with the new model once they're available.
247802


It's hard to see in OPs pic but you can kinda see the seals in this pic
247803


@kmichaelokelly Did you by chance notice if the Wilwoods had the seals/dustboots?
 

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Another thing that should be accounted for when talking about larger rotors aside from thermal mass and inertia is the mechanical leverage you gain by increasing rotor diameter from the center point. You simply gain braking force without even accounting for swept surface area, hydraulic pressure or thermal friction.
 

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Yep, they started a while back with the Aero 6 caliper and started cascading to the rest of their calipers from there. I don't really have a time frame as to what model got them when but Wilwoods site will update with the new model once they're available.

It's hard to see in OPs pic but you can kinda see the seals in this pic

@kmichaelokelly Did you by chance notice if the Wilwoods had the seals/dustboots?
I am fairly sure that they do not have the dustboots... the black around the piston is just where they had taped off the piston when powder coating to red from the standard grey/black.

If I would have seen that these were available I definitely would have tried to go that route, and seeing as they were available in red I only would have been looking at another upgrade of $35 per caliper for the dust boot option.

This would be a great thing to ask AZ Performance about as an option for everyone moving forward, but could be somewhat costly if you didn't want it in one of the two colors its available in.
The wheels are going to account for the majority of the increase there.

Wilwood 13.06" rotors have a total rotational inertia of .152 kg-m2 (that's meters squared, apparently we can't superscript here)
That's .031lb-ft2 (feet squared)
Or 2.15PSI

OEM 11.89" rotor have a total rotational inertia of .116 kg-m2
Or .023lb-ft2
Or 1.59PSI

So we have an approximate difference of .56PSI of pressure required to spin the larger Wilwood rotors over the OEM. There's at least a couple of chapters of grad school level physics (probably engineering too) involved in converting all that to something comparable to HP of Lb/Ft torque. I am definitely not that smart and even if I was we've already hi-jacked OPs thread. And my head already hurts.

I've never seen or heard of any issues with it but with Wilwood going back and redesigning calipers to incorporate dust seals I imagine there is some evidence out there of wear caused by either dust or moisture.
No need to worry about hi-jacking the thread, and all valuable info. I would have loved to include more of an in depth breakdown, but to your point there was definitely a couple times I went down some mathematical rabbit holes that left me a severe headache!
 
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