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Old 02-13-2016, 08:11 PM   #676
Reagster05
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Ok, just for starters I didn't read all the posts just the initial one. As your completely correct on most of this lets get a little scientific here. When you hit your brakes what are you doing? Dissipating energy. The way your car does this is takes your moving kinetic energy and turns it into thermal energy via your brakes and tires. Why else do you think brakes and tires get hot when stopping. So In Saying this, do "bigger" brakes make a difference sure they do, is it measurable? Probably not. Now if you got bigger brakes, and did something to help cool them off. Now you're talking about that possibly changing. Why do you get brake fade? Is it because your tires can't lay the energy down? No it's because everything got hot and is unable to absorb as much heat as before. Keeping your brakes cool will do more than getting bigger brakes as it's all about energy transfer to thermal energy. But air is air and it can only cool so fast. Different alloys and materials absorb and discharge heat differently. This is where you see your change in brake performance. Your sticky tires transfer the energy to the road better.
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Old 02-14-2016, 12:13 PM   #677
16Rex
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.......so, I need Brembo's on my base Impreza, right? Just kidding.
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Old 02-15-2016, 07:44 PM   #678
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Nicely put.
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Old 02-15-2016, 09:19 PM   #679
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Awesome write up, completely agree with what you say i have just have one question? if your a track car wouldn't the only purpose of upgrading the brakes is for quicker response on the brake pedal to the brake pad for quicker bite so you wouldn't have to push so hard on stock brake system therefore being able to let you get back in the throttle sooner? Correct me if I'm wrong.
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Old 02-16-2016, 11:23 AM   #680
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LOL nice
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Old 02-17-2016, 03:33 PM   #681
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Quote:
Originally Posted by Reagster05 View Post
...The way your car [dissipates energy] is it takes your moving kinetic energy and turns it into thermal energy via your brakes and tires. Why else do you think brakes and tires get hot when stopping.
1. Tires get hot because of friction from rolling over the ground. Yes, they may absorb some of the heat dissipated from the nearby caliper and rotor, they may also absorb heat from the sun and nearby exhaust and the neighbor's cat that regularly pees on them, but your tire's primary job in braking is not to help dissipate heat converted from kinetic energy. Its job is just to stick to the road.


Quote:
Originally Posted by Reagster05 View Post
...Now if you got bigger brakes, and did something to help cool them off. Now you're talking about that possibly [stopping your car more quickly]. Why do you get brake fade? Is it because your tires can't lay the energy down? No it's because everything got hot and is unable to absorb as much heat as before.
2. OP is not talking about brake performance alone (I.E. just transferring heat energy), he's talking about actual stopping power for the entire vehicle. Wheels losing traction and locking up will happen WAAAAAY before any noticeable brake fade in nearly all panic situations while daily driving (again, the main argument of the original post, since 90% of people 99% of the time do not put their brakes through enough constant stress to make fading an issue on the open road). On a track, I'd take glowing red brakes and sticky tires over crappy tires and super-cooled brakes. Every time.


Quote:
Originally Posted by Reagster05 View Post
Keeping your brakes cool will do more than getting bigger brakes as it's all about energy transfer to thermal energy. But air is air and it can only cool so fast. Different alloys and materials absorb and discharge heat differently. This is where you see your change in brake performance.
3. As a rule, larger brakes are already more resistant to fade because they absorb/transfer/dissipate heat much more efficiently over the larger surface, so bigger brakes already keep your brakes cooler. If you want, you can duct air to help cool them off even more, maybe you can install an air conditioner at each rotor, or spray liquid nitrogen, but again, in almost all cases on the street, your tire will lock up eons before your brakes heat up enough to degrade stopping power via the brake fade phenomenon. And one more time, we're talking about stopping the whole car, not just the tires from rotating.


Quote:
Originally Posted by Reagster05 View Post
Your sticky tires transfer the energy to the road better.
4. Yes. From a physics standpoint, acceleration is the same as deceleration. Tires transfer the energy of accelerating against the car's inertia and within the threshold of usable friction (grip) to move it forward. Tires also transfer the energy of decelerating against the car's forward momentum and within the threshold of grip to slow it down. It comes down to the tires maintaining traction. If you had tires that could never lose traction, then you could argue that larger brakes would stop the car quicker, because they could convert that kinetic energy to heat better. Did I mention that stopping the tires from rotating sooner does not necessarily lead to stopping the car sooner? If a tire is locked up (no longer rotating) you're going to slide, and you're going to slide much further than if your tires maintained traction the whole time. Tires. Tires do the stopping. Brakes only help.

Tires.

Last edited by flat4banger; 02-17-2016 at 03:45 PM.
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Old 03-27-2016, 10:22 PM   #682
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Perfect write up. Couldn't agree more
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Old 04-28-2016, 06:35 AM   #683
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[quote=flat4banger;44194218]1. Tires get hot because of friction from rolling.....

I just bought an 05 sti with 46k on a clean one owner car, the only mods are sway bars, top hats and Gyrodisk front rotors, DBA rear rotors, it clearly has fairly new pads but the car doesn't stop like it should. Even under heavy braking it seems to be not as "grippy" as other cars I've driven. The brake lines were traded out to stainless also. I can seem to figure out why this is. The car was started everyday but not driven everyday it runs and drives fine. Any ideas on what the issue is?
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Old 04-28-2016, 10:59 AM   #684
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Quote:
Originally Posted by Rushofadrenalyn View Post

I just bought an 05 sti with 46k on a clean one owner car, the only mods are sway bars, top hats and Gyrodisk front rotors, DBA rear rotors, it clearly has fairly new pads but the car doesn't stop like it should. Even under heavy braking it seems to be not as "grippy" as other cars I've driven. The brake lines were traded out to stainless also. I can seem to figure out why this is. The car was started everyday but not driven everyday it runs and drives fine. Any ideas on what the issue is?
you aren't exactly clear.

do the brakes feel mushy, or off? or does the car not feel like its stopping as fast as you'd like?

If its the former - you probably need to re-bleed the system.

if its the latter - you need new/better tires.
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Old 04-28-2016, 11:12 AM   #685
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[quote=Rushofadrenalyn;44360836]
Quote:
Originally Posted by flat4banger View Post
1. Tires get hot because of friction from rolling.....

I just bought an 05 sti with 46k on a clean one owner car, the only mods are sway bars, top hats and Gyrodisk front rotors, DBA rear rotors, it clearly has fairly new pads but the car doesn't stop like it should. Even under heavy braking it seems to be not as "grippy" as other cars I've driven. The brake lines were traded out to stainless also. I can seem to figure out why this is. The car was started everyday but not driven everyday it runs and drives fine. Any ideas on what the issue is?
This statement is far too subjective. It could be any number of things:
- Poor brake fluid
- Poor brake pads
- faulty calipers
- non-performance tires / bad tires
- you only drove Pintos and Yugos prior
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Old 04-29-2016, 08:37 AM   #686
Rushofadrenalyn
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[quote=Samurai Jack;44361407]
Quote:
Originally Posted by Rushofadrenalyn View Post

This statement is far too subjective. It could be any number of things:
- Poor brake fluid
- Poor brake pads
- faulty calipers
- non-performance tires / bad tires
- you only drove Pintos and Yugos prior
They don't feel mushy. They just feel like it slips. My previous performance car was a 13 srt8 challenger. I'm not comparing brake systems it just seems that if I hammer on the brakes, that it's not grabbing he rotor properly. I installed new tires yesterday on the factory bbs wheels and that is not the issue. It seems when I hit the brakes and even if I hit them hard it is not stopping as it should. I'm going to rebleed the lines later to see if that's the issue. I noticed yesterday that the pedal goes down a little before it even starts to stop. Maybe 1/2 inch but it's hard to tell while I'm driving. And the pinto and yugo comment is awesome first thing in the morning.
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Old 04-29-2016, 08:25 PM   #687
Floody420
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Quote:
Originally Posted by Rushofadrenalyn View Post
They don't feel mushy. They just feel like it slips. My previous performance car was a 13 srt8 challenger. I'm not comparing brake systems it just seems that if I hammer on the brakes, that it's not grabbing he rotor properly. I installed new tires yesterday on the factory bbs wheels and that is not the issue. It seems when I hit the brakes and even if I hit them hard it is not stopping as it should. I'm going to rebleed the lines later to see if that's the issue. I noticed yesterday that the pedal goes down a little before it even starts to stop. Maybe 1/2 inch but it's hard to tell while I'm driving. And the pinto and yugo comment is awesome first thing in the morning.
Is the fluid leaking at all anywhere? I wouldn't count out the master cylinder either.
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Old 04-30-2016, 08:11 AM   #688
Paul_bfast
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Default First Post

Just joined and worth it for this post alone!

Paul


Quote:
Originally Posted by neversummer489 View Post
If you spend a few grand to get any 02+ Wrx or sti to 300 brake horse power then they have too much money and this is a non issue. However for those of use that get a fuel pump injs a turbo and a tune (1000-1500) then a 4k bbk is an obsticle assuming looks are a priority.


Now this may over simplify what Dave said but
these http://cgi.ebay.com/ebaymotors/Compl...Q5fAccessories


Are equal to these for 80% of use scoobie owners out there http://www.intensepower.com/en6frbbkis.html
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Old 05-02-2016, 01:35 PM   #689
flat4banger
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Quote:
Originally Posted by Rushofadrenalyn View Post

I just bought an 05 sti... ...Even under heavy braking it seems to be not as "grippy" as other cars I've driven...
As others have stated, you're still being kinda vague. What are you comparing the stopping power to, stock brakes? Or did the car have these mods before you purchased and you're just using arbitrary speculation as to how fast it should stop?

You say it feels like it's slipping. What is slipping? The tires' traction on the ground, or the rotor in the pads?

What new tires did you install? If they are the same performance level as before, you're not going to notice much improvement, especially if tires were your weak point before. Are you hearing any rubber chirping as you come to a stop?

If the pedal is moving significantly before braking occurs, that definitely sounds like air in the lines, which could mean low fluid and/or a leak somewhere. Keep in mind that pedal travel/initial bite differs from car to car, so here's my unprofessional recommendation:

Check your fluid level and quality (% moisture); check your pads for signs of glazing. If neither of those seem to be the culprit, then maybe try to find someone else with a similar setup and see if braking feels similar. Those 3 paths will likely determine your next step.
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Old 05-30-2016, 09:19 PM   #690
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good read.
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Old 06-09-2016, 12:15 AM   #691
1st WRX Aero
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Default $$$$

You just saved me a lot of money.
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Old 09-18-2016, 01:45 AM   #692
WilliHaM
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I just purchased tires for my 02 wrx,problem is I cannot use them to my potential because my brakes are garbage. I have duralast brake pads, which brand do you guys recommend?
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Old 09-19-2016, 08:07 AM   #693
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First of all, how do you expect anyone to give you any kind of valid answer with the limited info you provided?

Second, you NEED to go research this on your own. There are so many brake pad threads people have lost count.

You need to figure out:
- what tires?
- what is the tire limit?
- what kind of driving you do?
- what is our budget?
- what are your current issues w/the brakes?
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Old 09-19-2016, 09:54 AM   #694
flat4banger
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Quote:
Originally Posted by WilliHaM View Post
I just purchased tires for my 02 wrx,problem is I cannot use them to my potential because my brakes are garbage. I have duralast brake pads, which brand do you guys recommend?
Samurai Jack is right, we can't make anything but vague recommendations when you give zero information to go off of.
Imagine someone logging onto an anonymous internet forum and asking how they should get their haircut. Same concept.

That said, Hawk Performance and Stoptech are both popular brands. They have different options for different levels of desired performance and use. Go look them up and do your research.
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Old 09-19-2016, 08:54 PM   #695
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Default physics on lighter rotors

While I understand all the info Ive read here I didnt see anything that addressed the effect of reducing or increasing the rotating mass and its effect on braking. Apologies if it was stated and I missed it.

TLR Would the weight loss from something like the AP Essex big brake kit (-24 lbs off the nose) actually make a "performance braking kit" meet both criteria of reduced brake fade under the 1% of track/sport situations and increased stopping power in the 99% of braking (old lady, cop, red light)?
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Old 09-19-2016, 11:18 PM   #696
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Get some pads with a higher coefficient of friction at low to medium temperatures. Lightly scuff the rotors with some 80 grit emery paper and bed them in for ten minutes.

You'll be good.
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Old 09-20-2016, 06:56 AM   #697
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Quote:
Originally Posted by clayton_w View Post
TLR Would the weight loss from something like the AP Essex big brake kit (-24 lbs off the nose) actually make a "performance braking kit" meet both criteria of reduced brake fade under the 1% of track/sport situations and increased stopping power in the 99% of braking (old lady, cop, red light)?
If all you are doing 99% of the time is daily driving, they are not worth the cost, unless cost is of no object to you.

Without an in-depth read of the Essex kit, it would appear the weight loss, over OEM I presume, will be the calipers, which do not affect rotating mass, as the calipers do not rotate.

If the weight loss id from the rotors, then remember less mass in the rotor means less heat dissipation of heat by the rotors because they have less mass, which means the rotors will heat faster and stay hot longer. All that is bad.
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Old 09-20-2016, 07:13 AM   #698
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Quote:
Originally Posted by Samurai Jack View Post
If all you are doing 99% of the time is daily driving, they are not worth the cost, unless cost is of no object to you.

Without an in-depth read of the Essex kit, it would appear the weight loss, over OEM I presume, will be the calipers, which do not affect rotating mass, as the calipers do not rotate.

If the weight loss id from the rotors, then remember less mass in the rotor means less heat dissipation of heat by the rotors because they have less mass, which means the rotors will heat faster and stay hot longer. All that is bad.
Rotors appear to be steel still (if it was something nicer it would be plastered over the summary page). The calipers are aluminum so there is weight reduction there. Seems very expensive and to be geared towards a high end built car.
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Old 09-20-2016, 11:57 AM   #699
flat4banger
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Quote:
Originally Posted by clayton_w View Post
While I understand all the info Ive read here I didnt see anything that addressed the effect of reducing or increasing the rotating mass and its effect on braking. Apologies if it was stated and I missed it.
Reducing/increasing rotating mass will have a respectively positive/negative affect on acceleration, because it relates to the engine's power transmitting to the wheels pushing the car. I don't think it will have as direct an effect on braking, since there are slightly different mechanisms at play (momentum converting to heat, vs engine power overcoming weight inertia to accelerate forward). I could be wrong.

That said, reducing weight in general (not just rotating mass), will have a positive effect on braking, acceleration, cornering, gas mileage, and butt dyno.
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Old 10-06-2016, 07:33 PM   #700
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Holy crap you went HAM. Thank you lol. One of the first upgrades I wanted to do was to get brembo's on my car to which I was informed that if I wanted more stopping power, it indeed would have been stickier tires, not the upgraded brakes. So thank you. I only wanted the brembo's because the STI's had them xD.
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