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Discussion Starter · #1 ·
I just got some basic question about after market brake rotors...

1) Can you install bigger rotors with the OE calipers, or does each rotor size require a specific caliper size?

2) what's the deal with aluminum rotors? They're much lighter so they drop your rotating mass by a bunch, but Al retains MUCH more heat than steel rotors....

so what's the best way to get bigger rotors on the car? I've seen some that have a yellow (brass or gold) hue...what are those made of...and can I get some that AREN'T colored that are lighter (I think that yellow color looks kinda cheesy).
 

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Thinking Man's Engine
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1. Yes, some brake upgrade kits will allow the usage of the stock calipers.

2. Just lightness only. Good old fashion cast iron is still best. Carbon-Carbon ceramic rotors are excellent, but costs a lot of money. Some weight reduction can be achieved using aluminum hats.

PowerSlots & their drilled rotors have a cadmium plating on it to reduce corrosion.
 

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Yes you can use larger rotors with O.E calipers. It is a less expensive option. AEM are developing a kit just like this.
Generally rotors increase in thickness proportionally to the diameter. This is done to increase rigidity and heat capacity and is applicable to the racing industry. If you just want to reduce operating temperatures on the street well the AEM type kit is an attractive option.

Dont waste your time with Aluminium rotors. Lotus tried it on the Elisse and had heaps of problems. Now they have gone back to cast iron. Aluminium composite rotors is a great talking point at universities but in reality it just a great pile of FLUFF.

Zinc or Cadmium plating is all the rage with rotors these days to keep the cast iron discs looking pretty behind those open wheels. This plating is generally yellow or silver in color.
 

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Discussion Starter · #4 ·
cool, thanks for the info....I'm just trying to keep the "lump cost" down....I'd like to upgrade the rotors and then the calipers later. I"d REALLY like to get a bit of a rotating mass reduction in the proccess...but sound to me like that's not going to happen if I stay with steel rotors....or will they be somewhat lighter if I get cross-drilled ones? I can't imagine they remove THAT much material by drilling holes.

Will I be able to upgrade the rotors and LATER the calipers, or would I have to put different rotors on if I were also going to get new calipers that are not the same as the ones I'd get if I was going to use stock calipers (that made sense, right?).

Also, what size rotors should I be looking at? are rotors all the same (at least by size) or are they car specific?


Sorry about all the questions....just doing my preliminary research....the only other experience I had was replacing the drum brakes on my Wrangler with discs....and that was totally different....(and NOT CHEAP).
 

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You can reduce some unsprung weight by using two piece rotors w/ a aluminum tophat. Bigger savings w/ aluminum calipers.

Big Sky
 

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Thinking Man's Engine
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Big Sky WRX said:
You can reduce some unsprung weight by using two piece rotors w/ a aluminum tophat. Bigger savings w/ aluminum calipers.

Big Sky

Except for the rear rotors, because they share a similar parking brake design to Toyota, where the parking brake is basically a drum brake. Thus a two piece rotor is feasible, but very expensive. Chances are, like the AEM Celica brakes, the rear ones would be a one piece design.
 

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AEM have a dia 310mm x 10mm WRX rear coming very soon. Same hand brake just larger rotor diameter.
 

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Discussion Starter · #10 ·
thanks for all that VERY useful info I just have some final questions I'd like to clear up if you don't mind.

1) I looked at the OE rotors and they look to me like they're made from 2 metals...looks like the whole thing is made an aluminum-looking metal and has steel braking suface atatched to it....is that how the OE rotors are??? because then I wouldn't really be reducing my unsprung weight with "lighter" rotors if they're already light.

2) will the AEM rotors in the above post fit with my 16" rims or do I need 17's?

3) I can use the same calipers, but will need different size brake pads, right?

4) can I replace them 2 at a time or do I have to do all 4 at once? (can I just replace the rears and drive like that for a few weeks)

5) do I have to mess with the brake bias or ABS? any kind of brake system readjustments required?

thanks again, its not always easy to get "REAL" answers on the internet so I appreciate it A LOT.
 

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Blarg,

1. oe same metal throughout (savings w/ a 2 piece-aluminum hatted is small-just a bonus)

2. don't know, you'll have to check w/ AEM

3. you'll be using the oe caliper thus the same pads (same size if you replace pads)

4. yes, very common to do just front or rear

5. no

Big Sky
 

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Most of the braking is done by the front brakes. You're better off getting the front brakes first, rather than starting at the rear.
 

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Although larger rotors help with heat dissipation I think the better way is to upgrade the caliper and rotors together. That way you get better heat holding capabilities coupled with better clamping force and bigger pad size. Now as far as alluminum I think what he meant was a two piece rotor with alluminum hats. These are a good choice since you have the iron piece for the main rotor material but allminum in the center portion to lighten up weight and help cool the wheel bearings (since the hats are usually an open design). ceramic metal matrix or carbon fiber are the best materials but cost upward of $3000+ just for the rotors and special pads you need.
 

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I'm starting my brake upgrades soon:

First, I am putting on Endless NA-S pads in the front with DBA slotted one piece rotors.
Second, I am replacing my brake fluid with some high performance stuff.

After my rear brakes wear out, I'll be doing DBA slotted rotors and NA-S pads there too.
If I am still not satisfied, I'll try some stainless steel brake lines, but I think the stock pedal feel is excellent, so they may not be necessary.

I'd get Subaru four-piston calipers, but I want to be able to use my stock rims for rallying and/or winter duty.

-Jim
 

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Does anyone know if the STi 4-pot calipers will fit behind the WRX oe 16" wheels? I assume they use the stock discs...

Regardless, it seems like heat could be a problem with uprated calipers and stock discs. Anyone care to comment? I was considering this route because I want to stick with my oe wheels for the forseeable future, and am therefore wondering how limited I am with my brake upgrade options.

-Pace
 

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The Subaru four pots won't fit under the wrx oe wheel unfortunately. It's the 6.5" width that prevents it, the 16X7 RS wheels will clear the subaru 4 pots. They do use the stock rotor (or same size aftermarket).

I don't think heat will be of any concern w/ a four pot using oe size rotors.

There are a couple of options w/ oe rims (I too use mine for winter/gravel duty) 1. Upgrade pads, ss lines and a quality DOT4 fluid (that was the route I went- Endless CCX front, NAY rear) 2. A couple of vendors are carrying Wilwood dynalite calipers (4 pots) that use the oe size rotor and fit under the oe wheel, they also have 2 pot rear that will be available soon. 3. KVR is close (maybe a month) to releasing a 4 pot caliper that will also use the oe size rotor and fit under the oe wheel. 4. Rotor upgrades- couple of different outfits selling oe size rotors- including DBA.

Big Sky
 

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Actually the Subaru 4 pots WILL fit under the OEM WRX wheel. You just need some small spacers (perhaps 3mm) in the front. The Wilwoods are not very impressive to me in terms of quality although they are a pretty good value. KVR makes good kits using AP calipers although AP already has 2 or 3 kits out already.
Jim, remember you want to install the rotors and pads at different times. Bed each in seperately that way you get less problems later on.
 
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