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Home > Performance Mods > Suspension & Brakes > Big Brake Kits

Big Brake Kits

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TC1032

Reg'd: Oct 17, 2007

Tire Changer

Im looking for a big brake kit, but i don't know the first thing about them. So, i'm kinda having a hard time figuring whats what.
well, i know the difference between the drilled and slotted and because my TC is my DD i was thinking of getting both drilled and slotted so things can work out. all in all, im lost. Any tips for brake kits?

[#] Feb 18, 2008 09:44am
nick06tc


Reg'd: May 20, 2006

Vehicle Designer

Only tip I have is, you probably dont need it.

The only reason for a big brake kit is for the Points at a car show, or if you are doing track events where you are running 20-30 laps or whatever.

The tC does not have break fade and no matter how big the brakes, you wont stop any faster with bigger brakes during daily driving. If the you slam the break pedal in a stock tC and the ABS kicks in, then they are grabbing as good as they ever can. Even with bigger brakes you wont stop faster.
Even while autocrossing I have never seen brake fade because you are only driving for less than a minute.

Now if you are getting it for the car show scene, then I understand that. So to the question. A big brake kit isnt about if the rotors are drilled or slotted. What makes them bigger is a larger rotr, which means you will need either a larger caliper or new mounting brackets for the stock calipers.

Stoptech makes a really nice kit. But expect to pay $1000-$2000 for a real big brake kit.

[#] Feb 18, 2008 10:10am
Web


Reg'd: Apr 17, 2006

THE SHADOW

Actually, larger rotor and caliper = larger surface area for pad to grab. Upon moderate braking without having the ABS kick in, you will stop a bit harder....more pressure per square inch with multiple pistons in each caliper.


I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones. A.E.
[#] Feb 18, 2008 02:19pm
nick06tc


Reg'd: May 20, 2006

Vehicle Designer

hm... you might be right, but I dont agree. Just from my understanding. The stopping power of a vechicle is dependent upon traction of the tire, and clamping/grabbing ability of the caliper/rotor. If EVERYTHING on the car is the same (mainly vehicle weight) the stock calipers/rotors, if they have the ability to bring the rotor to a full stop (or abs kick in) there is going to be no change. Unless brake heat/fade has set in. (and in street instances this shouldnt be happening. If you increase the clamping/grabbing like you say, yes it will stop the car better at the same brake pedal engagement. But all that means is you wont have to push the break pedal as hard to stop in the same distance. But overall stopping distance will still be the same because total stopping power has not increased, because the limit is lock up/abs. And the stock can lockup/abs just the same as a BBK.

Now if you add ALOT of weight to your vehicle or VERY large/heavy wheels. I do agree with you, because you now have more force to bring to a forward/or rotating stop.
And you can increase wet weather stopping possibly. But tires will be the limiting force there any how, so I doubt you will see a difference.
(I could be wrong in all of this tho)

[#] Feb 18, 2008 03:35pm
nick06tc


Reg'd: May 20, 2006

Vehicle Designer

Thought of a good analogy.

If you take a your finger, press it on the table really hard and try to slide it, enough pressure and friction will stop your finger from moving.
Do this with your hand, takes less pressure pushing on the table to stop your hand from moving.

More surface area means more friction. But as long as you have enough pressure/muscle to push your finger to stop the added surface area isnt needed, except to save energy.




Now convert this to brakes. The stock tC has enough brake power to creat enough friction to stop the rotor.
Add larger rotor and caliper and you have more surface area, but need less brake pressure to stop it all. Yeah its cool and all, but the breaking system has the ability to do it with the stock pressure/muscle.


Now where it is needed analogy.
Hand on desk again. With the finger you will get tired. so using your palm is better.
With a rotor on a race track you brake alot, so heat is created, larger rotor less pressure less heat, less brake fade!!!


Hope that makes sense, it does in my mind!!

[#] Feb 18, 2008 03:40pm
Web


Reg'd: Apr 17, 2006

THE SHADOW

100% agree.....tires are the main stopping power behind any vehicle. No matter how big your brakes are, your tires are the only things touching the pavement.

Nice analogy by the way.

BBKs I can see on cars pushing serious horsepower around tracks, but for normal street use...it's just overkill and not much help. Proportionally, it's a big difference in road course races to help with braking distance and overall brake temperature.


I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones. A.E.
[#] Feb 18, 2008 05:16pm
TC1032

Reg'd: Oct 17, 2007

Tire Changer

thanks you guys. wait so what's the point of having drilled and slotted rotors if tires is all that really matters?

[#] Feb 18, 2008 11:26pm
SuperXero

Reg'd: Mar 31, 2005

Chief Mechanic

drill slotted is for high speed braking. if you've ever seen someone smash on their brakes at high speed you might notice their rotors start turning red which reduces stopping power. the drill/slots provide air circulation and keep your rotors cooler

[#] Feb 18, 2008 11:43pm
Web


Reg'd: Apr 17, 2006

THE SHADOW

Slots helps expell dust mainly and some gasses that build up between the pad and rotor. Drilled rotors help against water soak (it drips off and throught he holes leaving a dry, flat surface) and help gasses escape a lot faster.

Only thing is...ebay drilled rotors are not recommended due to high tendencies to crack. Slotted is the best bet for normal street/strip use as they are structurally more stable.

If you go to autocross events, almost all events will not let you run with cross drilled rotors (unless stock...Porsche) b/c they don't want to risk your rotors cracking during a run. Slotted and flat rotors are ok though.


I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones. A.E.
[#] Feb 19, 2008 10:18am
Web


Reg'd: Apr 17, 2006

THE SHADOW

SuperXero wrote:
drill slotted is for high speed braking. if you've ever seen someone smash on their brakes at high speed you might notice their rotors start turning red which reduces stopping power. the drill/slots provide air circulation and keep your rotors cooler


The only time you will see your rotors glowing red are if you come to an extremely hard/fast stop repeatedly with our cars. It takes a lot of heat to get those things red hot so on street use, it will most likely not happen unless you're trying to do it. The red hot glow happens when the rotors/pads don't have enough time to cool between braking periods and the heat just keeps building up. This leads to brake fade, which slotted and drilled rotors help reduce.


I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones. A.E.
[#] Feb 19, 2008 10:20am
FrAnkRYzzO


Reg'd: Oct 21, 2005

$upervillain
for Hire

Quote:
Only thing is...ebay drilled rotors are not recommended due to high tendencies to crack.


While the ebay cheapies are going to be more prone to crack, any rotor that is actually drilled or slotted after the casting process is going to be prone to cracking. The only drilled or slotted rotors that are not going to have their structural integrity compromised are ones that are cast with the holes or slots.

When metal is cast it has a grain in it like the inside of a tree. Drilling through the grain disrupts these and therefore makes it weaker in those areas and overall. When the holes are cast in the rotor, the grain wraps around the hole like a knot in a tree and none of the grains are interrupted. Anyone who has ever had to split wood with an axe and came to a piece with a knot in it will understand what I'm talking about. Brembo is the only company that I am aware of that makes aftermarket rotors that are cast with the holes. That's why they are so much more expensive.



Even Zombies can Search...
..............
.......................................................................Why Can't You?!?!?!
[#] Feb 19, 2008 11:25am
dsm3383


Reg'd: Mar 14, 2007

Scion Guru

First of all, larger rotors = larger contact force which leads to better braking. Tires do play a role but comparing with the same tires but brakes with larger rotors/pads you will experience a performance gain in your braking system.

Second, big brake kits don't just operate off of larger rotors. Yes, the stoptech cheap "big brake" kit does but it really is not a big brake kit.

A true big brake kit (Wilwood, Brembo, etc...) truly gets the stopping power from your caliper upgrade!!! We have a measly two piston caliper on our tC. Get a Brembo upgrade and you can choose between a 6 or 8 piston caliper. That is a huge substantial increase in hydraulic power to mash the pad against the rotor and distribute the force evenly through the pads. That is truly the largest factor when you examine big brake kits.

Third, cast holes/slots are weaker than machined. Rotors most important material property for operation is being HARD. When you machine metal you "cold work" the metal which increases stresses in it that change the grain structure at those HAZ (heat affected zones). The grain structure changes to being harder and more brittle (better compression strength). So, in reality machining after casting will create those areas (the slots/holes) where most people will assume as the weak spots actually the strongest parts on the rotors.

You also have to remember that you have to machine the rotor after being cast to produce the finished product. So, you automatically build these stresses in the rotors unless it undergoes a heat treatment process afterwards. Brembo only casts with the holes because its less material consumption thus cheaper manufacturing cost. They make it cheaper and sell it to you for more cause it is the "brand" name.

Beer is proof that God loves us and wants us to be happy.

-Ben Franklin
[#] Feb 19, 2008 12:09pm
WendysOrBust


Reg'd: Feb 19, 2008

Window Washer

dsm3383 wrote:
First of all, larger rotors = larger contact force which leads to better braking. Tires do play a role but comparing with the same tires but brakes with larger rotors/pads you will experience a performance gain in your braking system.

Second, big brake kits don't just operate off of larger rotors. Yes, the stoptech cheap "big brake" kit does but it really is not a big brake kit.

A true big brake kit (Wilwood, Brembo, etc...) truly gets the stopping power from your caliper upgrade!!! We have a measly two piston caliper on our tC. Get a Brembo upgrade and you can choose between a 6 or 8 piston caliper. That is a huge substantial increase in hydraulic power to mash the pad against the rotor and distribute the force evenly through the pads. That is truly the largest factor when you examine big brake kits.


The amount of brake pressure that is available to use is directly affected by the type of tire you have. You will achive better, streetable gains trough the stock caliper and pad upgrade with some very nice tires. Rather than spending 2k on a bigger caliper setup, while you ride on the oem all seasons, it would be more benifical to upgrade other parts of the car first, such as stiffer suspension, pads, and tires.

dsm3383 wrote:
Third, cast holes/slots are weaker than machined. Rotors most important material property for operation is being HARD. When you machine metal you "cold work" the metal which increases stresses in it that change the grain structure at those HAZ (heat affected zones). The grain structure changes to being harder and more brittle (better compression strength). So, in reality machining after casting will create those areas (the slots/holes) where most people will assume as the weak spots actually the strongest parts on the rotors.

You also have to remember that you have to machine the rotor after being cast to produce the finished product. So, you automatically build these stresses in the rotors unless it undergoes a heat treatment process afterwards. Brembo only casts with the holes because its less material consumption thus cheaper manufacturing cost. They make it cheaper and sell it to you for more cause it is the "brand" name.


Wrong, the holes are cast in giving a dense boundary layer-type crystalline grain structure around the hole at the microscopic level as opposed to drilling which cuts holes in the existing grain pattern leaving open endgrains, etc, just begging for cracks. Here's a quote from SCR Motorsports.

SCR Motorsports wrote:
Crossdrilling your rotors might look neat, but what is it really doing for you? Well, unless your car is using brake pads from the 40’s and 50’s, not a whole lot. Rotors were first ‘drilled’ because early brake pad materials gave off gasses when heated to racing temperatures – a process known as ‘gassing out’. These gasses then formed a thin layer between the brake pad face and the rotor, acting as a lubricant and effectively lowering the coefficient of friction. The holes were implemented to give the gasses ‘somewhere to go’. It was an effective solution, but today’s friction materials do not exhibit the same gassing out phenomenon as the early pads.

For this reason, the holes have carried over more as a design feature than a performance feature. Contrary to popular belief they don’t lower temperatures (in fact, by removing weight from the rotor, the temperatures can actually increase a little), they create stress risers allowing the rotor to crack sooner, and make a mess of brake pads – sort of like a cheese grater rubbing against them at every stop. (Want more evidence? Look at NASCAR or F1. You would think that if drilling holes in the rotor was the hot ticket, these teams would be doing it.)
[#] Feb 19, 2008 02:05pm
FrAnkRYzzO


Reg'd: Oct 21, 2005

$upervillain
for Hire

^^That's what I was thinking. I was doing some research on rotors today and I kept finding the same conclusions:

1. That any rotor with a hole through it increases the chances of cracking (cast or drilled)

2. Casting the holes reduces this risk but does not eliminate it

3. That the only benefit drilled rotors provide are for water removal or for lightening the rotor (useful on a motorcycle)

I actually found the same quote from SCR Check out this link I found. It's a discussion about this same topic on an rx-7 forum. There are a series of quotes from brake designers and manufacturers towards the bottom of the thread that seem relevant to our discussion:

http://www.rx7club.com/showthread.php?t=480082&page=2




Even Zombies can Search...
..............
.......................................................................Why Can't You?!?!?!
[#] Feb 19, 2008 02:42pm
nick06tc


Reg'd: May 20, 2006

Vehicle Designer

dsm3383 wrote:
First of all, larger rotors = larger contact force which leads to better braking. Tires do play a role but comparing with the same tires but brakes with larger rotors/pads you will experience a performance gain in your braking system.

Second, big brake kits don't just operate off of larger rotors. Yes, the stoptech cheap "big brake" kit does but it really is not a big brake kit.

A true big brake kit (Wilwood, Brembo, etc...) truly gets the stopping power from your caliper upgrade!!! We have a measly two piston caliper on our tC. Get a Brembo upgrade and you can choose between a 6 or 8 piston caliper. That is a huge substantial increase in hydraulic power to mash the pad against the rotor and distribute the force evenly through the pads. That is truly the largest factor when you examine big brake kits.

Third, cast holes/slots are weaker than machined. Rotors most important material property for operation is being HARD. When you machine metal you "cold work" the metal which increases stresses in it that change the grain structure at those HAZ (heat affected zones). The grain structure changes to being harder and more brittle (better compression strength). So, in reality machining after casting will create those areas (the slots/holes) where most people will assume as the weak spots actually the strongest parts on the rotors.

You also have to remember that you have to machine the rotor after being cast to produce the finished product. So, you automatically build these stresses in the rotors unless it undergoes a heat treatment process afterwards. Brembo only casts with the holes because its less material consumption thus cheaper manufacturing cost. They make it cheaper and sell it to you for more cause it is the "brand" name.

I dont see anything true about this post.
Again, I am no expert tho, but the rationality behind it all just doesnt seem to make sense or match anything I have ever hear or read. (Doesnt mean I am right tho)

Tires are the 100% limiting factor, UNLESS the stock setup has the in ability to take the wheels to lockup/ABS. And the tires are what determines that point.

If you have tires made out of SOLID frozen ice and you apply your brakes they will instantly go to lock up because traction will be lost. If you have tires made of CONTACT CEMENT it is going to take ALOT of pressure to bring them to lock up because they are going to grip everything and bring the car to a hault. Now apply that to a narrow range of a better tire over another tire and it all still applies, (just not so blown out of proportion)

yes like you said, a larger surface and caliper will give you more breaking force, but if the original force has the ability to stop the rotor from turning, how can there be more of an ability to stop the rotor from rotating? (short of makeing it spin backwards!!!!!!!!!)
The only gain is it takes less pressure to stop it from rotating due to the surface friction. Now that would be wonderful if the stock setup had human muscles and got tired. But our system driven on a road or even autocross, will NOT fade.

(none of this applies to a large circuit track, then you are right you will see MAJOR gains because brake fade and wear will become an issue.)

Oh and see my analogy of friction in my 2nd post.
[#] Feb 19, 2008 03:29pm
Mayo


Reg'd: Feb 14, 2007

The Guru

nick06tc wrote:
yes like you said, a larger surface and caliper will give you more breaking force, but if the original force has the ability to stop the rotor from turning, how can there be more of an ability to stop the rotor from rotating? (short of makeing it spin backwards!!!!!!!!!)
The only gain is it takes less pressure to stop it from rotating due to the surface friction. Now that would be wonderful if the stock setup had human muscles and got tired. But our system driven on a road or even autocross, will NOT fade.

Oh and see my analogy of friction in my 2nd post.


Nick, I think what dsm said might actually fit your analogy. Braking relies on friction. More friction equals less more braking power. Allow me to bring some equations in to this.

F = u x N

F - frictional force
u - coefficient of friction
N - Normal force

In this case, the N is the amount of force the pistons of the calipers apply. In order to increase frictional force, either 'u' or 'normal force' must be increased.

Now, surface area has nothing to do with this, but pressure of the brakes do. If the Brembo kits apply force with 6 to 8 pistons, they are increasing the normal force, therefore increasing the frictional force. That means more braking power.

In you analogy: Sure 1 palm will slide almost as easily as 1 finger. But imagine 6 to 8 hands on top of your palm pushing down. That would make is much harder to move your hand.





"I have an idea! An idea so smart, my head would explode if I even began to know what I was talking about." - Peter Griffin
-- Want to post a "For Sale" thread? Check out the rules first.
[#] Feb 19, 2008 03:42pm
Orin


Reg'd: Dec 08, 2005


well done

good information in any case

[#] Feb 19, 2008 04:14pm
Web


Reg'd: Apr 17, 2006

THE SHADOW

Mayo wrote:
nick06tc wrote:
yes like you said, a larger surface and caliper will give you more breaking force, but if the original force has the ability to stop the rotor from turning, how can there be more of an ability to stop the rotor from rotating? (short of makeing it spin backwards!!!!!!!!!)
The only gain is it takes less pressure to stop it from rotating due to the surface friction. Now that would be wonderful if the stock setup had human muscles and got tired. But our system driven on a road or even autocross, will NOT fade.

Oh and see my analogy of friction in my 2nd post.


Nick, I think what dsm said might actually fit your analogy. Braking relies on friction. More friction equals less more braking power. Allow me to bring some equations in to this.

F = u x N

F - frictional force
u - coefficient of friction
N - Normal force

In this case, the N is the amount of force the pistons of the calipers apply. In order to increase frictional force, either 'u' or 'normal force' must be increased.

Now, surface area has nothing to do with this, but pressure of the brakes do. If the Brembo kits apply force with 6 to 8 pistons, they are increasing the normal force, therefore increasing the frictional force. That means more braking power.

In you analogy: Sure 1 palm will slide almost as easily as 1 finger. But imagine 6 to 8 hands on top of your palm pushing down. That would make is much harder to move your hand.




Shoot me in the foot for this, but I don't believe adding more pistons will add more force. The force is controlled by the valves in the master cylinder and simply adding more pistons would actually just spread that force out ACROSS the rotor area thus, actually REDUCING clamping force as a whole. It's more bite surface but with less pressure per sq/inch. I initially thought it would be more pressure but it's simply more CONTACT patch with the same amount of force.

Increasing fluid pressure will increase caliper pressure....just updrading the calipers will not increase the pressure in the lines.

That seem logical to anyone?


I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones. A.E.
[#] Feb 19, 2008 05:05pm
Orin


Reg'd: Dec 08, 2005


don't upgrade brake kits like Brembo have devices for increasing hydraulic pressure?

[#] Feb 19, 2008 05:09pm
WendysOrBust


Reg'd: Feb 19, 2008

Window Washer

Yes, ANY time you are planning on upgrading your calipers it's almost a must to also replace the Master Cylinder with a larger one. I don't think anyone is arguing that larger caliper will theoretically work "better" The point I was trying to make is that on a street application it is almost pointless to upgrade to such a big kit, without doing the basics first. The only way I would ever see myself purchasing a Brembo bir brake kit is if I was running R-Comps to the track. There are much better ways of improving your cars braking power, and distance than purchasing an expensive big brake kit.

[#] Feb 19, 2008 05:25pm
Orin


Reg'd: Dec 08, 2005


^ agreed,

if you're wanting to spend money on aftermarket rotors for looks for example, spend a little extra money on a quality rotor.

that should bring us back to the concern of the original post, which rotors to buy

[#] Feb 19, 2008 05:32pm
Web


Reg'd: Apr 17, 2006

THE SHADOW

Just talked to the Porsche forman and he agreed. Larger calipers and rotors will give you larger bite surface area, but with stock pressure in the lines and ABS, you're limited by the main factor....YOUR MASTER CYLINDER.

Big brake kits, unless you have a race car or are pushing serious power/speed and have upgraded pressures, are just a waste of money and just for looks.


I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones. A.E.
[#] Feb 19, 2008 05:37pm
WendysOrBust


Reg'd: Feb 19, 2008

Window Washer

Orin wrote:
that should bring us back to the concern of the original post, which rotors to buy



lol, yes, true.

The way I see rotors is I will always buy blanks. As far as rotors theres really not too much of a science; as far as blanks go. Unless you are buying rotors for a certain type of metal or material used, I don't think anyone should be buying expensive rotors. Drilled rotors offer zero gains, and I'd only use a slotted rotor if I was using a race brake pad that created allot of dust. Other than that instead of wasting money on gimmicky parts one should invest in a much better pad that will work better troughout the heat range and will provide more friction.
[#] Feb 19, 2008 06:37pm
Web


Reg'd: Apr 17, 2006

THE SHADOW

I do all highway driving and braking so I needed something that was going to constantly deglaze my pads and scrape a new wear surface onto them. That's why I chose my setup and it's been very quiet and enjoyable since my installation.


I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones. A.E.
[#] Feb 19, 2008 06:41pm
dsm3383


Reg'd: Mar 14, 2007

Scion Guru

Well a more powerful master cylinder is always needed and in my eyes implied if you are planning on a big brake kit.

Yes, I do agree it is absolutely a waste for a street car. If your not braking constantly at high speeds for an extended amount of time, like seen on a track, then it is just for show.

My point was just to state that a "real" big brake kit does include a drastic difference in the performance capability of a braking system compared to a stock set-up. I was not infering to a street application at all.

Tires play a huge roll when it comes to braking hard at high speeds (stopping really fast also). The reason so is the coefficient of friction for the tires. Better tires have higher coefficients thus desired!

This allows your tires to always be in control with the ground during braking. This is the scenario you want since you will remain in control and no extra stresses are being applied to the braking components.

Sliding is not desired since you don't want your brakes to lock up the wheel but your still moving. NOT GOOD! This happens when the rolling friction forces overcome the coefficient of friction in the tires. The brakes being more powerful are the cause. This is the scenario being discussed as tires playing a huge roll and yes I totally agree.

What I stated is all around braking. Increasing the contact area for the force applied along with larger forces applied will increase braking capability. If you want to brake going around a turn it will take a shorter time to reduce your speed which is what you want.

I hope this makes sense to all.

Beer is proof that God loves us and wants us to be happy.

-Ben Franklin
[#] Feb 19, 2008 06:47pm
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