Factory Calipers....what fits and doesnt.
 

So have been reading different things on what factory calipers and rotors will fit and what wont.

Can we get a list going of what does and does not work. I was looking for new BBKs and would really prefer to stick with some oem setup just so there are more/cheaper options on rotors and pads available.

I was looking at the willwood kit, but does that mean i am then stuck with willwood pads and rotors only?

I found these....
2006-2007 WRX 4pot/2pot
Will they work? Anyone have experience or know?

Thanks!

What is your actual goal in replacing your brakes with something else?

Looking for just a bit more stopping power. Plus now that i am ironing out my tune, would like to start doing at least 1 track day per month.

The stock system seems to fade now under hard driving. I have only noticed it once, doing some datalogging. Basically 3rd gear wot pulls then braking to pretty much stop. This after 10 minutes or so and the brakes felt bad, like scary bad. This was at about 280hp.

Just thinking of getting something a bit beefier. Now i am at about 350hp, so can only imagine it will be worse? Wan to fix it now, rather than have some break fade/failure on the track.


Was looking at some remanufactured brembos, or just do the willwood kit. I really like how easy it is to swap brake pads on the willwood.

Get some decent pads + upgrade your fluid, and you should be good to go for most track events.

-alex

This!

Bigger rotors and more pistons won't add stopping power or fade resistance, you need pads meant for track use and a higher temperature rated fluid.

HP doesn't heat up brakes, traction does. If you've got more grip than stock you need to beef up the brakes regardless of how much power you're making.

On stock pads I couldn't get ABS to engage with 225 width Dunlop ZII's unless it was COLD out, with just new fluid (ATE Super Blue) and pads (Ferodo DS2500's) it'll engage ABS even on a hot and sticky day.

Or look at it differently:

If you upgrade to a BBK and use factory Subaru fluid, your brakes are just as bad as before.

Since upgrading to a better fluid gives you fade resistance (one aspect of it, the other are pads and, to a lesser extent, rotors), then why not go for the cheapest upgrade first with the least hassle?

Brake lines also help immensely.

-alex

Why not AP Sprint?

Why the interest in the WRX 4-Pots? I know on the 05-09 Legacy GT they were actually a downgrade despite "looking" better. Might want to make sure they are even marginally better than stock...

-Pierce

Tires. /thread until....

Are you a track novice?

If so, pads, fluid and better tires (not R comps though).

If you are still having issues then think about increasing thermal mass. Which choice suits you best then depends on what you want. Everyone here probably knows where I stand on this one.. Once you have some experience and know that you really need more thermal mass then come back.

BTW, the calipers by themselves will increase feel a little and modulation a little, all else being equal nothing will change. No increase in thermal mass, etc. Bias may change a little so performance could improve or get worse. IIRC those calipers are less effective than our stock ones so Bias would move rearward, not ideal.

Bigger rotors = increase in thermal mass, which means more heat removal from the calipers/pads, which will decrease the duration that the calipers, pads and fluid have to deal with the heat generated from the friction of the pads against the rotor. So yeah, "larger" (quotes because diameter isn't the only form of larger) rotors will help prevent fade by being able to remove more heat, and more importantly, ABSORB more heat from the system, which is one of the primary jobs of the rotor.

Of course, bigger isn't always better and one can screw up a brake system pretty nicely with poorly designed or chosen "upgrades".

Well, sounds like just pad and fluid upgrade will work. Do i need to upgrade the lines to stainless as well? Maybe run that, and then later upgrade the rotors?

Will try that for a bit and see how it feels.

Track Novice. Never been on a track with a car. Use to race bikes alot, but i know, totally different.

Larger discs are not just about heat capacity. It increases the effective lever-arm of the brake system to give you a different pedal feel. I'm putting 330's on mine purely for this.

Doesn't matter how much heat the rotors can absorb unless they can keep the pad temps in a range the pads are happy with, and I can't imagine there's a rotor big enough to do that with stock pads :D

If you're overheating race pads with stock diameter rotors and aren't driving wrong, then sure there's a case for bigger rotors, but for 90% of the people out there they just need better pads and fluid.

Horsepower absolutely DOES heat up brakes! Braking from 80mph to 40mph requires 21.5% more energy than braking from 75mph to 40mph. BIG difference! More power requires more capacity to dissipate heat energy from the brakes, it's a fact.

You may be able to get up to speed quicker with more horsepower, but unless you're on the throttle while braking, stopping from 80mph with 1000 horsepower is the same as 80mph with 100 horsepower. Obviously with more power you'll likely have higher peak speeds (on a track), which could translate to needing more braking power.

What Dan is saying is:

On a given track, with specific parameters, you'll get to a faster top/entry speed with more HP, so you need more heat dissipation on hand for the brakes, where BBKs come in handy.

-alex

Edit: you edited right when I quoted you...

Once you've determined you are ready for a brake upgrade there are some good options out there. Like @Dave-ROR said, be careful when selecting an "upgrade" as it is easy to mess up performance. My personal track choice has always been AP Racing but there are plenty of other good bbk's out there that will work and help with your track days.

Remember what Dave said,
Adding too much rotational mass can actually hurt your braking (and accelerating) performance.

Yes, you will have more brake torque with a larger rotor. You will also have more unsprung rotating mass farther from the axle centerline. It can also screw up your brake bias and increase stopping distances, but rock on :thumbup: I never noticed any real change in pedal feel just from larger rotors, but calipers.. yes. It may be there but I'm not good enough to notice it, by feel I'm assuming we are talking about tactile feedback and not what the body of the car is doing, etc.

These are all reasons why brake upgrades should be properly designed. I think a lot of us have went through the "I'm going to run XXXmm front brakes with 4 pots..." only to use the same brake marker on track and end that braking zone with a "oh shiiiiiiiit" due to improperly thought out changes. Not saying that you haven't taken these things into account.

Sorry I didn't realize we were limiting that conversation to stock pads. I agree with you generally, but there are other benefits to brake upgrades. My pads are cheaper than OEM size for one. My pads and rotors also last longer. They are also lighter than OEM parts. Better brake feel too.

Just sayin... :)

Speaking of brakes, I really should install those SS lines that have been sitting around for a year. There's absolutely zero need to do so but I'm kinda sick of looking at them taking up shelf space in my garage. :shrug:

Drive a stock 2002-2005 WRX then drive a 2002-2005 WRX with "H6" rear rotors. The difference isn't in the pedal, it's in how the car stops and how much the front end dives.

Legacy GT had 316mm front rotors, so moving to a 290mm-ish rotor wasn't the smartest move. On this car, the rotors are identical up front so the 4 pot isn't a "BBK" as much as it simply an opposed-piston fixed caliper that feels better.

I think you've assumed i'm not also changing calipers. I can assure you that is not the case.

I appreciate what you're trying to say about rotating mass - I have found that it doesn't really become an issue (gyroscope effect) until you get to ~380mm or larger.

I assumed that you would switch calipers too. My point was just that larger rotors increasing feel is something I haven't experienced. Other parts often involved in that will, but you can increase rotor size without replacing calipers, etc (custom brackets, different brackets, etc).

I tend to follow this path:
1. If I beat on the car on track for extended periods of time, does it fail?
2. If yes, what's the best way to resolve it without increasing mass?
3. Does that change require a rear brake change to resolve any bias issues? If so, are more agressive pads (up to a point) enough?

That's simplified a bit, but... basically I want AS SMALL of brakes as I can get away with. If I can make them lighter and cheaper overall than stock that's a great bonus. I never want more thermal mass than I *need* because it's not as ideal as having "just enough". I currently run ~more or less OEM diameter rotors, they are just a lot thicker with a lot better cooling. They hold up to abuse and have help up to boosted track cars without issue so I just will never see the *need* for huge brakes on these.

I am curious on opinions (backed up or not) on Cross Drilled and/or Slotted Rotors as and upgrade for stock braking systems.

Do we really have to go there again? lol

I'll grant slotted rotors can have a purpose but I honestly don't feel that either are an upgrade for a stock brake system. Both remove mass (less in slotted) and introduce stress risers (again less in slotted). Neither are additional features I want in a brake system that is, IMO, borderline for extended track use already. They add some noise as well but my car sounds like a dump truck mixed with a frieght train under braking so I don't care about that.

Of course I barely track the BRZ anymore so.. oh well. My dedicated track car and the race car have even smaller brakes.. with sliding calipers.. oh the horror.. err. :shrug: :)

So does mine, and having slots or espeically cross drilled holes are just places for cracks to start in my $15 rotors made proudly in China. :lol:

Speaking of that, I need to go pickup some more mini cooper rotors for the GS-R.. they are ~$30 each :~(

I personally like the application of slotted helping keep the rotor and pad surface clean. I agree with Dave in that removing a lot of mass from the rotor just hurts thermal capacity. I do love the look of cross drilled rotors but as far as being applicable for performance I stray away from them. Seems to be more of a gimmick than anything (not in reference to Carbon Ceramic Brake which I don't know much about).