11 minute read
By Bryan Leonard, Pro Race Car Driver and Chase Bays Builds Manager
The fact is, manual brakes are on the fastest road race cars in the world. From IMSA to F1. But how is this possible!? You read online it was like trying to put your foot through a brick wall! How exactly can manual brakes improve lap times?
The major point I drive home to all those that I coach; consistency. If you can be a consistent driver and make decisions with intention rather than reaction, you are setting yourself up for success. So to be fast we have to be consistent drivers. We are the throttle, brake, and steering actuators on a car.
That means we need those things to be consistent. Throttle is generally consistent (unless you get into DBW with throttle shaping but thats not for this convo). Steering can be consistent if it is either manual, electronic, or properly cooled and managed hydraulic power steering. We also assume our suspension setup is correct and not out of alignment, producing consistency there too.
Braking consistency, this is the last step. I have and will always stand by the comment: braking is the hardest thing to do to extract a lap. How you get on the brakes, how long you are on them, when you release them, the time frame you release them in coupled with steering angle. That's hard stuff.
There is a reason why you see Miatas at the track beating up Corvettes and Porsches. Of course there is the driver mod, but doesn't that mean the Miata driver is utilizing the brakes more effectively? Because they certainly are in a lesser power car.
Now here's how we pull it off. I spoke of consistency earlier, we need to be proactive not reactive with everything we do. In order to accomplish this, we have to have a consistent pedal. The manual brake is the surest way to accomplish this. In a prior blog, I used the analogy of pressure from your finger to a wall. Here is a refresher, if I ask you to place your finger on a wall and give me a little pressure, you can do that, if I ask for a lot of pressure you can do that as well. Just because the wall didn't move doesn't mean there was no pressure applied to the wall.
So with a more firm pedal we can produce brake pressure that is consistent and predictable. With this you will be able to repeat results each lap because the pedal feels the same way. You will have the confidence that heading into 10a at Road Atlanta, that your brake pedal will feel exactly the same each time, thus allowing you to play with brake zone depth and releases. As we stated before, its also important how and when you release the brake pressure as well. Now that we know what the initial force feels like and how quickly the car decelerates. This will allow us to properly set up braking zones.
In conclusion, the opportunity list looks like this.
1. Consistent pedal feel (assuming proper setup, no air in the system, or overheated brakes)
2. Allows us to easily explore gains and loses in the braking zone by playing with brake timing and release.
3. Trains us to be proactive rather than reactive to our pedal. Power brakes inconsistency in pedal feel cause slight hesitation. This lowers driver confidence thus hurts lap times.
This is an example of a power assisted brake. Notice how the pressure is inconsistent? This could be due to the fact that the pedal moves to much and the driver "pumps" the pedal trying to get it to slow down.
This is an example of a manual brake trace. Notice how the initial braking force is high and slowly tapers off. This is what the brake trace should look like, this eliminates braking distance thus resulting in faster lap times.
These are all dual master setups with balance bars. They are great, but it’s not exactly in most of the grassroots/amateur motorsports worlds budget. Enter the Chase Bays Dual Piston Brake Booster Delete with Bolt-On 6:1 Pedal Ratio. This system allows you to receive many benefits from the manual brakes, without the fab/cost of an expensive system. Having now driven with this system, and won our first race with one, I can confidently say this is your ticket to faster laps. We took someone with zero experience with a manual brake, installed this system on his car, he immediately went faster. The only piece of advice I would give is to pump your brakes before the braking zones. Not a large amount of pressure, maybe 10%...just enough to reset the pads. Unless you have anti-knock back springs you need to do this. The power brakes give off the false sense of not needing to do this. I can assure you, you need to. When you strike curbs or load a side, the pads will push back a little. Thus the pedal will travel further making it seem like you have a long pedal. This happens on manual or power brakes. The power brakes just mask this a little bit more. By giving the brakes a small tap with your left foot pre-turn, you will have knocked the pads back into place.
Anyone that I have introduced to manual brakes have questioned why they didn’t do this sooner. I would list this Chase Bays mod as a must for any track day/ grassroots/Am racer where the series allows it. Its compact, its attractive, the engineering is already finished.
As I said before braking is the most crucial thing you can do on track. People should stop worrying about horsepower and start wondering how to get their mid corner speed up. The way to do this is to properly execute braking zones. Ditch the factory components, get a Chase Bays Dual Piston Brake Booster Delete. You will easily go faster immediately and become a better driver. Things to remember:
Set the pads in the straights right before a braking zone
Initial brake force is the highest, trail off, as you wheel angle increases, steering angle should decrease.
Release gradually, do not snap off.
Chase Bays sells many brake component products, and in doing so we receive many questions regarding the function of our setups. There is a lot of misinformation and misunderstanding when it comes to brake hydraulic function. Here are 4 facts to help better understand braking.
1. Master Cylinder Bore: Larger vs Smaller
One of the most common misconceptions is that a larger master cylinder will create more pressure. While a larger master cylinder creates a larger displacement, it takes more force to create the same pressure as it would with a smaller bore. The result after adding the larger master cylinder bore is a harder pedal which requires much more pedal pressure to create the same amount of brake clamp force. This result displays itself as a combination of undesirably high force and unpredictable braking response. In more specific terms, moving from a 3/4" master cylinder to a 1" requires 77.7% more force on the push rod to reach the same amount of clamping pressure. Our goal was to develop a product that balanced the entire system. We factored in pedal force, system pressure, and lever travel and the 7/8” Wilwood fit the bill in every category.
2. Eliminating the Brake Booster: Impact on Braking Function and Pedal Feel
It is not uncommon for us to hear people say that eliminating the booster will cause the pedal to be too stiff for reasonable braking control. While we cannot disagree that some people do have this issue after eliminating their booster, their issues are always due to improper design and setup. Every bore has an appropriate pedal (or lever) design required to produce a certain level of pressure. The key to a great pedal feel and more controlled braking is a properly balanced master cylinder bore in relation to the pedal ratio (the length from the pedal swing mount to where it attaches to the master cylinder) used, with an adjustable proportioning valve before the rear brake lines.
In a brake boosted setup, the purpose of a brake booster/vacuum servo is to reduce the amount of pedal pressure required to push the master cylinder. In doing so it creates inconsistent braking because of varying vacuum levels within the chamber. It is very common in race cars (and show cars) to eliminate the brake booster to attain more consistent and controlled braking. After removing the booster the pedal does get stiffer but it is still reasonable for street and track use (much like the difference in pedal feel after changing from stock to an aftermarket clutch). The stiffer pedal feel allows better brake modulation now that there is no booster between the driver and the master cylinder. Our Brake Booster Eliminator kit ensures the master cylinder size is paired properly with the pedal ratio on street cars. Chase Bays offers a Brake Booster Eliminator Kit, Adjustable Proportioning Valve, and Brake Line Relocation Kit for various chassis.
To see more about these Chase Bays brake products, click HERE
3. Cross-Drilled and Slotted Rotors: The Basics
Cross Drilled Rotors
Cross drilled rotors are OE-style blank rotors that have been cross drilled to allow heat to escape that builds up between the brake pad and rotor through the drilled holes and out the mid rotor vent channels. Many people prefer drilled rotors because they like the look and consider it a good upgrade over an OEM blank rotor. The problem is that the integrity of the rotor is moderately compromised which combined with extreme temperatures and pressure can allow them to crack between the drilled holes. Thus even though drilled rotors are specifically designed to expel hot gases, most available on the market are not built properly and the holes serve merely an aesthetic purpose. If you are set on buying a drilled rotor, we recommend a quality brand such as DBA, Brembo, or Wilwood.
Slotted brake rotors are a great alternative to drilled rotors because they serve the same purpose of expelling hot brake gas, but since they retain the strength of the rotor, they are not prone to cracking in the same fashion as cross-drilled rotors. They are also easier on the brake pads in terms of wear.
What's best for the street vs the track?
Most of our customers will notice more of a difference in stopping performance by changing the brake pads than the rotors. The advantages from cross drilled and slotted rotors comes during extremely hard and repetitive braking such as in competition use. For street use, we believe the best bang for the buck is to get a quality set of slotted brake rotors, suitable brake pads for your driving style, and replace your rubber fender well brake lines with stainless steel brake lines.
4. Brake Pad Quality Breakdown
There are different types of brake pads for different purposes. The qualities we demand from a street pad is completely different from what we need out of a race pad. Day-to-day street driving pads generally demand the following characteristics:
- Never make any noise
- No dust on our fancy wheels
- Good cold bite on the way to work
- Effective in the rain and snow
- Last 100,000+ miles
- Never wear out rotors
However, our priorities shift when the weekend rolls around. We want our race pads to have the following characteristics:
- Enough heat capacity to never fade after repeated lapping on a racetrack
- Predictable torque response for precise brake pedal feel and modulation
- No required bed-in or preparation
- Immediate release from the discs when we let off of the brakes
- No uneven pad deposits or scoring of the rotors
- Little to no wear as temperatures increase
Each driver must determine the most important pad characteristics for the type of driving he or she will be doing and choose a pad strategy with acceptable compromises. Out of often hundreds of different pad options, each pad compound will exhibit different characteristics and potential drawbacks. The goal is to find a happy medium based on how the car us used. Every situation is different.
With this article, we hope to help people understand braking components better so they can build a functional system suitable for their demands. If you would like to see a full article on specific pad types including their strengths and drawbacks to help you determine which is best for each type of driving…let us know!