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Discussion Starter #1
So my 02 Wrx stock rotors are warped (all four) and here are the vast choices, based on current vendor offerings and For Sale forums:

Fronts, NEW:
"nice" BBK new ($1000+): either Stoptech, Rotora, Brembo

"good" BBK new ($600+): Subaru 4-pot, Perrin

Fronts Used:
-Brembo take-offs: $700-$900 (various wear)
-Subaru 4-pot: ~$500 (including new rotors)

Rotors only:
DBA regular and club spec 4000
Stoptech
Brembo
stock, slotted, cross drilled or combination.

The rears:
(I won't even bother going into BBK rears, waay too $$$)
-Legacy rears: vented rotors and bracket to match stock calipers.
-H6 rears: solid larger diameter rotors and brackets to match stock calipers.

My question:
First do I have things right? I can't say I'm much of an expert here and I know there's a few more BBKs out there, but these are the popular ones.

2nd: I know the Subaru 4-pot has less dampening force than the current stock 2-pot calipers, but better modulation "feel". I'd like to know what the dampening forces are for the BBK. Most poepl say BBK are for show and racing. Not practical. The BBK shortens braking distance, how is that not practical? That difference can save your life. It's like saying yu don't really need airbags, cuz most of the time you'll never use them...

It's all mind numbing, but I guess have good choices is a blessing.

ONe thing no one ever mentions is brake proportioning valves where you can dial in brake bias (or dial out). why do so many people talk about adding brake bias when a valve can be added (at little cost I assume) to adjust the whole thing.

Well, I'm frustrated and I still don;t know what I want. Feedback and advise is welcomed...

Hg.
 

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I'm going through the same process right now, except my rotors aren't warped.

the thing you have to consider through all this is how heavy are your wheels?

for example if you look at all the HUGE brake kits out there, you also see HUGE 18" rims that are pretty heavy. remember that adding 1 pound of spinning rim weight eats A LOT of power, both accelerating and decelerating.

The best brake upgrade you can do is get yourself a set of Kosei K1 17" rims. At 13.5 pounds a piece you're shedding 12 pounds of spinning wheel weight (that's A LOT), and at $200 a pop its cheaper than even the least expensive caliper upgrade. because you're reducing your wheel weight that much your stops will be shorter and your acceleration will be faster.

the other reason to get bigger calipers is if you find yourself having to stop from 100+ MPH the extra pad area will help there as well.

I decided to just upgrade the brake lines with SS lines, AEM blue brake fluid, and some Axxis Metal Master pads (because the Ultimates that everyone else gets produce WAY too much dust).

You can probably pick up a set or rotors for under $300. most of the guys that sell drilled or slotted rotors are using OEM blanks to do it, and all that extra work doesn't really make a lot of difference. Mostly its just bling factor.

drilled rotors are weakened by drilling. modern pads (since about 1960) don't produce any gasses so there's no point to drilling. the only "good" drilled rotors are made by Porsche. They're actually CAST with the holes in them, but again, this is just for bling.

slots scrape the pads to keep them from glazing when you make high speed stops, but they reduce the life of the pads. they also GREATLY increase the production of brake dust so you always have dirty wheels.

I'd say get some OE rotors, SS lines, and some good fluid and do a complete flush. in the caliper department the Perrin or Subaru 4-pots in the front and turbo legacy rear upgrade will be plenty unless you want to run 19" wheels with spinners.
 

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Discussion Starter #3
Hey, I appreciate your comments.

Any way to quantify your points on the unspun weight theory? I know it's more than a theory, but I'd like to get some hard proof on the performance difference between 13lb wheels and 17 lb wheels. Stopping distance, acceleration, and like. Sure it makes "sense" an dseems logical, and everyone states it....I'd like some hard evidence.

I've got SS lines, better fluid, Hawk pads (street). They made a diff, but now my rotors are warped and so I need to upgrade anyway.

Do you know if the legacy rears are larger rotors or just vented?

Hg.
 

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The normal Legacy rotors (H6) are just larger rotors. The Legacy Turbo sport sedan and wagon rotors are larger and vented but you have to get the larger calipers. The H6 rear upgrade is an excellent brake upgrade from what I've heard. I'm ordering mine next week to go along with my Subaru 4-pots.
 

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I wasn under the impression that that the trubro legacy rotors were the same diameter as the WRX rotors, but they were vented. so you need a wider caliper to get around them, and the legacy turbo rotor is a 2-pot one.

so if you do a Subaru/Perrin 4-pot front and the turbo legacy rear you decrease your overall stopping distance but you don't mess with the brake bias as much as other upgrades might.

sorry I don't have any actual numbers/physics on hand and since its 5 am and i'm pissed because the dogs woke me up to go outside to pee and I can't get back to sleep but I'm tired as hell I'm not really inclined to go looking right now.

i'm sure someone else who got more sleep will provide you with ah ling if you wait long enough for wheel weight/rotating inertia/unsprung weight crap. you might be able to find something if you search for "unsprung weight".
 

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QuickSilver said:

2nd: I know the Subaru 4-pot has less dampening force than the current stock 2-pot calipers, but better modulation "feel". I'd like to know what the dampening forces are for the BBK. Most poepl say BBK are for show and racing. Not practical. The BBK shortens braking distance, how is that not practical? That difference can save your life. It's like saying yu don't really need airbags, cuz most of the time you'll never use them...

Hg.
Not always true. A BBK will not shorten stopping distance in most cases. If you can activate your ABS system, you have enough brake torque to lock your wheels, which means you're basically stopping as fast as is possible w/ your tires being the most important factor.

I'd say just get some new rotors if your current ones need replacement. You can certinaly make gains by reducing unsprung weight, and tweaking all sorts of things, but I'm not sure how far you'd have to go to see a really noticeable difference. I upgraded my suspension recently, and with a stiffer setup my braking is certinaly improved as far as the response. I don't have nearly any dive, and it just feels more firm because energy is going to stopping the car, not compressing the springs. my 2 c
 

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that's a very good point. if you can lock the brakes you have more than enough power. when I drive my girlfriend's Kia Sorento, I can push the brakes all the way down to the floor and the thing still plows like....well...like an SUV. Its a really creepy feeling when you hit the brakes expecting to stop like a WRX and suddenly realize that you have another 10 feet to go.:eek:

her 17" rims weigh about 22 pounds a piece and she has old tires.

if you want to recude your stopping distance, save your money and just get some new OE rotors. the best way to go is better/wider tires, make sure your struts are in good working order, and reduce unsprung weight.

oh yeah, drilled rotors actually REDUCE the contact area between your pads and rotors, which is why usually you see them coupled with bigger brakes. they'd be just as effective with just one row of holes radiating out from the center or one slot on the whole rotor, but that would look odd so its not done that way.
 

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The Turbo Legacy rotor is the same diameter as the H6 rotor but is also vented. The rear caliper on the Turbo Legacy is also a single pot but is wider and with a larger piston. I however think that the Turbo Legacy rear upgrade is overkill and the H6 upgrade would be sufficient.
 

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A true BBK (larger diameter rotors) is needed if you frequent the track a lot. It's sole reason for being is to withstand repeated (<-this being the key word) hard braking. The larger rotor dissipates more heat- it's that simple.

Many times BBK's will have less brake torque up front than your oem setup and can actually lengthen one time braking distances- this is not necessarily bad as the oem setup is very (too much IMO) front biased. Less torque up front will shift bias to the rear, thus the popularity of the "H6" upgrade- it shifts bias to the rear by adding torque to the rear. You can also effect torque w/ brake pads (different coeffecients f/r).

Tires are the number one key in braking- that's a given, take care of your tires first.

Pads can also positively effect braking distance- a higher coefficient pad will create more brake torque, generally higher coefficient pads also have higher operating temps- you have to balance these two features. Too high of operating temps and you could be in trouble driving to the grocery store and your pads won't grab. Too high of a coefficent and rotor wear will be accelerated. Thus the reason that many have track dedicated pads that go on @ the track and a street pad used day to day.

It all boils down to need. For a street driven car, the oem setup w/ decent pads, fluid, lines will suffice. For those that drive more spirted, a "H6" upgrade will help w/ bias- you'll experience less dive and more of a squat.

If you may or will see some track duty, then pads become even more important on choice. High quality rotors (ie DBA 4000 series) become a good investment as they can withstand the heat generated @ the track. Ducting of some sort also should enter into the mix.

If you want to take it to the next step you can look at the Subaru four pots- again as you mentioned for better feel/modualtion, better (more even) pad wear on hard braking, a wee bit less unsprung weight, ease of pad changes and a few more minor advantages (including less front torque).

If your a die hard track fan, then your only real option is a quality BBK- our cars are heavy and the demands of repeated track events will neccessitate bigger brakes.

Lots to consider when upgrading brakes, but they are a very important consideration for obvious reasons.

Big Sky
 

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I'm no brake expert but wouldn't having slotted and drilled OEM sized rotors reduce even more unsprung weight? I was thinking of getting slotted and drilled OEM size rotors just to save some more weight. please correct me if I'm wrong.
 

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in theory, yes. In practive it won'r remove enough weight to make a significant difference. If you still have seats in your car and carry a spare, you'd probably see a bigger difference by removing those than you would by getting drilled/slotted rotors. On the other hand, the weakening effect of driling the rotors will definately be something you'll see eventually...especially for racing. I know they don't look as cool, but solid-face rotors really are best for daily driving and weekend racers. Slotted rotors offer a little more fade resistence by scraping the pads on every rotation to keep them from glazing (which you will only see under extreme repeted baking), but reduces the pad life and increases brake dust production.

despite what any rotor manufacturer tells you, the only "drilled" rotors that are just as strong as solid-face ones are made by porsche. They are not actually drilled....they're cast with holes, and they're VERY expensive. This is something that Porsche does for a "signature" look for their rotors, and offers no practical benefits...seems like a lot of money to pay for a little bling.
 

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blarg said:
in theory, yes. In practive it won'r remove enough weight to make a significant difference. If you still have seats in your car and carry a spare, you'd probably see a bigger difference by removing those than you would by getting drilled/slotted rotors. On the other hand, the weakening effect of driling the rotors will definately be something you'll see eventually...especially for racing. I know they don't look as cool, but solid-face rotors really are best for daily driving and weekend racers. Slotted rotors offer a little more fade resistence by scraping the pads on every rotation to keep them from glazing (which you will only see under extreme repeted baking), but reduces the pad life and increases brake dust production.

despite what any rotor manufacturer tells you, the only "drilled" rotors that are just as strong as solid-face ones are made by porsche. They are not actually drilled....they're cast with holes, and they're VERY expensive. This is something that Porsche does for a "signature" look for their rotors, and offers no practical benefits...seems like a lot of money to pay for a little bling.
I see :cool: so it would make a difference just not really a noticeable one.
I can't beleive porsche would go through all that trouble to get original cool looking brakes! I guess it's ok when you have money to burn
 

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Well years ago drilled rotors did make a difference. The reason being is the older pads tended to produce gasses under high temperatures like those in racing. The holes actually vented the gasses. The gasses acted like a cushion between the pad and the rotor. Venting those gasses allowed the pad to contact the rotor more evenly. Todays pads do produce the gasses that older pads did but not in the quantity. The porchse rotors allow for a marginal increase in cooling of the rotor, and like slotted rotors cleans the pads with every pass. The drilled holes do serve a purpose but one that can be handled by a much simpler and less strength reducing slot.
 

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The slots allow them to out-gas as well.
 

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QuickSilver said:
So my 02 Wrx stock rotors are warped (all four)...

I'm frustrated and I still don;t know what I want. Feedback and advise is welcomed...

Hg.

1/ I find it hard to believe that all of your brake rotors are warped. What brake pads did you run before this happened?

2/ What do you want? Brakes that wont warp for as little money as possible or a better braking car?
 

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Discussion Starter #17
I used HAWKS HPS all around.

I want awesome brakes. Reliable and resistance to fade...even after aggresive canyon runs.

as an update to this post...I got Brembo STi take-offs up front. I figured that I might as well get the best...and although Stoptech folks may disagree...I don't think many can top Brembo in reputation.

the Brembos ROCK btw!
 

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I would look into cryo frozen rotors if you want a long life. When cryo frozen the metal structure is realigned and is much more stable. All or most of the internal stress is removed from the metal and therefore makes for a much more thermally stable brake rotor that can sustain high temps and not warp. If this sounds interesting check out http://www.frozenrotors.com
 

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QuickSilver said:
I used HAWKS HPS all around.
Those are low friction pads. Are you sure you didnt just smear them all over the discs like you do when going down that canyon road?


QuickSilver said:
I got Brembo STi take-offs up front. I figured that I might as well get the best...

the Brembos ROCK btw!
You have "Brembos" and "they rock"? :D These calipers are 15 years old, first introduced on the F40, then on the Evo 5 in 98 (and subsequent models)...
 

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Discussion Starter #20
new doesn't necessarily mean better. I'm not saying the brembo tech is the best out there, but they have a great rep. for my purposes, I think they work great. No fade that I can notice and nice pedal feel.

In hindsight, I think the pad material just left deposits on the stock rotors causing the vibrations. The vibrations were very servere tho'.
 
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