How to select the right brake pads & equipment. feel free to ask Brake Questions in the comments.

Johnny C is the majority of my real name. I'm a "brake guy" by profession and by hobby. I have an obnoxious amount of brake tech swirling around my noodle. If I crammed that info into a Book, nobody would read it. It's some of the driest information anyone could imagine. If and only if you have an issue with your brakes would you pay attention. 

About me: I'm a former PFC Brakes factory Rep. I've worked with top racing teams like Joe Gibbs racing, Ganassi, Rum bum, Irish mikes, so on, and so on. I've been in the Motorsports world professionally starting in 2006. I've worked hand and hand with teams and engineers to build braking systems and to fix issues with braking systems. 

If you having an issue with your brakes, please ask. Or if you are looking to upgrade your brakes, please ask. The majority of club racing related braking issues I come across, are from individuals who tried to upgrade their system without properly educating themselves first. 

ask in the comments below. 

So you know that company that says it’s stainless steel lines will shorten stopping distance? Well they are full of shit.  

Brake System. 

The very first thing that you need to comprehend is that brakes need to work as a system. Rotors, Pads, calipers are all components. Those components alone are as useful as tit’s on a bill. They need to work together to get braking performance. I will cover what each components job is and how it will affect the system. In this I will briefly cover the only 3 components that will Change torque in a system. Pads, Rotors and Hydraulic advantage. So you know that company that says it’s stainless steel lines will shorten stopping distance? Well they are full of shit.  

Balancing the system. 

“How do we make a system work on a chassis?” is a loaded question. So many variables enter it like how heavy is the car, does it have down force, how many ex-girlfriends are packed into the trunk, how late are you, What kind of tires are you using. To avoid very large and complex question. We will assume most people reading this will have a street car, GT style of race car, or some sort of lemons creation. If you have a down force car like a Indy car or Daytona prototype have your engineer call me. For those with a normal track day type race car (previously mentioned)  we want to find a balance like Goldie Locks not too much front bias and not too much rear bias. I hear a lot of “my brakes are fine I can lock a tire at any speed” if your locking a front tire at 100mph your brakes are not fine, they have too much front bias. You are leaving performance in the chassis. When I see a car coming hot into the pits I want to see the rear tires lock a millisecond before the fronts. Watch a NASCAR race and see what those cars do. On the race leaders you’ll see the rear lock up first. On my novice track day drivers I will set up the brakes with a slightly heavy front bias, on my experienced club racers I’ll still set them up with a moderate front bias. Extra front bias This is in an effort to stop people from having too much trail braking and spinning out in the braking zones. The pros throw cars into turns, they love trail braking.  But balance is the Key if you upgrade the front brakes do not forget about the rear brakes.  

 How to balance a system.

When it comes to manipulating brake TQ you have 3 options.  1. Pad Compound 2. Rotor Size 3. Hydraulic advantage. That’s it! So that place that says their brake fluid increases TQ they are low down dirty liars. your split fire sparkplugs, sham wow, goo that goes on the backing plates, dyno mat, or hitting a rock will not change the Tq output of your brakes. Hitting a large rock will change your speed quickly but it won’t change the tq output.  How each of these components effect your braking will now be discussed below. please apply the information to the axles of your car to balance it.     

Pad Compound and how to select the right one. 

Brake pads can be broken up into the 3 phases of how they work. Initial bite, TQ output, and modulation.

number one Initial bite. this is the characteristic of a pad on first contact with the rotor. if you where to look at a brake dyno you would see a spike at initial contact followed by the Tq level and then how the pad modulates off. this is spike in the dyno is considered "initial bite" Or "bite". Initial bite is purely driver preference. Manufacturers have a tendency to keep that characteristic throughout their pad offerings. hawk has a tendency to have a very high initial bite. PFC and Pagid are a more mild initial bite. Allot of Club racers like a High initial bite. I hear things like "I want to get thrown into the harness". That sounds fun and all, but professional drivers (the really fast guys, not the pay to play guys) like a low or mild initial bite. the really fast guys like a mild initial bite because it helps the tire keep cohesion with the track. This will allow you to brake harder and deeper into the turn, giving you a few extra tenths. A lower initial bite is also easier to drive on. I recommend a full GT pad for beginners. because of the ease it engages the rotor. Drifters. I always recommend hawk to drifters as the initial bite is so high it helps them break the back tires loose to start a slide.

Torque output or "Mu". This is the part when guys get really excited.. I get requests for "I want the highest MU pad you got.." unless you have one of Chip Ganassi's old Indy cars this would be a very bad idea. Pad Tq is not in any way like Horsepower-"more is good!". the Tq of a pad need to be matched to your application. Brake Tq in a pad has another characteristic, Consistency. General conception that a pad that a professional uses is harder to drive on. They are professionals right? the pro cars are insanely hard to drive. when it comes to horsepower and crazy over steer that is true. it's not true when it comes to the brakes. in fact it's the opposite. a world class pad is insanely consistent throughout its entire temperature range. This means when a driver is leaving the pits or diving into turn 10A at road Atlanta the pedal will feel exactly the same. That cannot be said for a low price economy race pad. even the HP+ has a strange tq rise with heat. (I’m sure I’m getting some Head nods from people that know the hp+). When I’m setting up a car for a beginner I encourage them to spend the extra $$ on a “pro” set of race pads. It makes the learning experience that much easier for them. When I say pro-pads i don't mean super high Tq pads (i'm talking about the pads pro's use, PFC & Pagid). The higher the Tq is, the less forgiving a pad becomes. If you have an insanely high tq pad on a car that isn't set up with slicks and downforce you're going to overload a tire easily. the Bite of the pads will become very hard to drive , the tq will overload the tires, you'll never get any heat , and you can forget about the transfer layer. the pad compound needs to be matched to the chassis. That key in difficult driving leads me on to modulation..

Modulation! modulation is also known as release characteristics. What it feels like to release the brake pedal. Modulation is generally linked between pad TQ and chassis set up. for example we will look at the PFC 07 compound. the 07 is a very high tq Compound. On a Indy car (the chassis the 07 was made for) with huge slicks and tons of downforce. the 07 will feel normal, you'll be able to ease off the brakes. the brakes would still give you a good linear release. on a lemons car, 200qutg tire, no aero. The 07 will feel like a light switch, Linear Fell would be a dream with that setup. let’s reverse it. if you were to install a 97 compound (good for a underpowered gt car or a rally racer) on to an Indy car. The modulation would be wonderful, you could modulate all day. you would not have significant tq to adequately slow the vehicle down.

To rehash match the compound to the tire.

A Quick run down pf PFC pads and the tires that should be used.

Compounds: --97/14----------08----------01/11---------05/07
Tire QUTG:  400----------200----140-------50-------Full slicks

*note i have used PFC01 compounds on Rivals and other new age 200qutg tires. it works fine modulation is acceptable. tQ output can lock a tire and care must be taken to not flat spot a tire.  

Rotor size and what to look out for. 

Rotor size is an excellent way to increase TQ. It basically has no trade off other than weight most BBKs (big brake kits) come with 2 piece rotors. So the larger rotor can be lighter than the rotor that came off the car. Remember that Rotational mass is 4X as important as sprung mass. So pulling 50lbs of rotational mass off of the car is like removing 200 lbs out of a chassis.  

About a rotor and why a good one matters.

there are allot of different aspects when it comes to a rotor. 
What is it made from (Iron, Steel, Aluminum, Carbon ceramic, Carbon Carbon)
Where is it made
Is it 2 piece (hat made from aluminum, Rotor ring made from iron) 
if it is 2 piece does it float? 

Not wanting to spend all day i'll try to keep the answer short. and focus on the standard parts store rotor. 
Standard rotors that you find on Rockauto, Autozone, and so on come from china. They are covered and machined with oil, the material to make them is not as pure as it should be, and are never made engineered for racing. allow me to explain. 

The machining process for Chinese rotors involves blasting the machining surface and tools with an oil to keep them cool, this lowers maintenance costs on machines. Then factory workers will warp the rotors with an oil impregnated paper. This oil is in an attempt to prevent rust, at that it works well. The problem with using so much oil is that, it will impregnate itself into the iron. once that iron is impregnated the oils will come out under extreme braking. Most of the time when you see issues creating and keeping a transfer layer, the oil inside the iron is causing that issue. It impurities in the rotor are kicking the transfer layer off. Racing companies like PFC, Brembo, AP, will cut the rotors "dry". Dry means to machine the parts without any oil. it is more expensive to do this but will increase the rotors ability to obtain and keep a transfer layer.

Next is what it's made from. Iron is easily one of the best materials used for rotors. Size for size an iron rotor will outperform a carbon ceramic rotor. if you have 14" rotors one in carbon ceramic and one in iron, the iron one will generate a more consistent and higher TQ output. Not to go too off track but that is why you see 15-16" carbon ceramic rotors on oem vehicles. The oem manufacturers need the increased size to get the performance. but Carbon ceramics will outlast a iron rotor. ...sorry back on topic, right iron.. Iron is one of the densest materials in the universe. also how pure it is in the casting for a rotor makes a considerable margin in braking performance. rotors that are casted in china are known to have quite a few impurities, and are labeled incorrectly. anyone that has dealt with 304 *chinese* stainless will know what i'm talking about. these impurities will have a decreased effect on braking performance. I like to find Rotors manufactured and casted in the usa. the us has a higher standard of casting. again PFC, AP, and brembo all are manufactured in the USA, GB, or Italy. 

finally the engineering in the rotors could take year to explain, so I’ll focus on balancing only. when a rotor gets hot it cones, it beds, and it looks like a wave. it's never still. The material is constantly flexing. think about a top fuel dragster tire in slow motion.. it's not 100% the same but it is close. that rotor is constantly trying to keep itself together and not explode. in order to stop a rotor from shaking the wheel all manufacturers will balance them. Top Motorsports brake manufacturers will balance the rotor by cutting the entire outer perimeter of the rotor on a lathe. this ensures that when a rotor is at thermal capacity, there will be no places of excess or minimal material. it makes the rotor stronger, and more resistant to cracking. part store rotors balance the rotors by finding the heavy spot on the rotor and cutting that off.   

In Motorsports this is a huge no-no. the hard edges give a place for cracks to start, the material has a thin spot on the rotor, and it means that the material that is spinning is not balanced through the assembly. it can lead to a cracked rotor and can lead to problems with a long pedal. 

In conclusion, :P. is high quality rotors a waist? Like tools good quality parts are never a waste. On average a Motorsports rotor will outlast a parts store rotor long enough to justify the price. Parts store rotors can work, they also let allot of people down. If it was my money, paying for my track day, i'm putting the parts on my car that will insure that i have a fun weekend. i'm not looking not fight the $30 rotor that costed me $800 of track time. Allot of people might say "they worked fine for me". Truth of the matter is 80% of the motorsports population knows how to build a motor, 10% know how to build a braking system. when the brakes that they said "worked fine" didn't work "fine", and that person has no idea what the problem actually is.

Hydraulic advantage.
correcting .... 

Brakes are only a hydraulic system so by simply changing a cars master cylinder to a smaller one you can increase line pressure. Fair warning the pedal assembly has a “point of no return”. Meaning once you past 90* (parallel) to the master cylinder you lose leverage on the master cylinder. So when picking out mater cylinders you want to reach lock up just before the peal box reaches parallel.    

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