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Inspired within Australia’s heartland, DBA developed the Kangaroo Paw cooling system. This patented ventilation system provides a much more efficient method of keeping the rotors cool under the heaviest of braking applications.
Using a series of 144 diamond and teardrop patterned pillars (or columns) instead of conventional straight cooling vanes, the design increases cooling efficiency by up to 20% when compared with most other conventional ventilated disc rotors.
As well as providing cooler conditions, the Kangaroo Paw system also provides additional support to the friction face. This enables the rotor to maintain the fine tolerances over the life of the rotor better than a straight vane design, which can “balloon” and swell between the vanes when operating at high temperatures.
The Kangaroo Paw pillars are evenly spread across the disc face and make the rotor stronger, more stable and more consistent in operation.
Standard conventional straight vane vs DBA’s Kangaroo Paw cooling system
The ventilation system of a brake rotor is best described as the foundation and support between the friction surfaces.
Other than material composition, another major factor that affects the thermal performance of brake rotors is the surface area within the ventilation design. The more surface area, the more heat that can be removed from the brake rotor.
The mass of the brake rotor also plays an important role. The greater the mass, the more heat that can be stored and must be dissipated, this is why the design of the Kangaroo Paw is so effective. This minimizes the risk of brake fade and restores normal braking much sooner.
After 30 years of design and development with race teams around the world, Disc Brakes Australia developed a proprietary cast iron formulation ( XG-150 ) for use in all of it’s premium performance disc brake rotors. DBA’s grey iron is rich in carbon and alloyed to produce excellent thermal characteristics, which is a key factor in the production of the casting. This is combined with our patented Kangaroo Paw ventilation design. With a supersaturated solution of carbon in an iron matrix, the excess carbon precipitates out in the form of graphite flakes. The structural distribution of these graphite flakes provide excellent thermal properties, increasing the thermal shock resistance. Also, when combined with DBA’s TSP process it allows the material to cope with rapid thermal cycling with core-heat levels reaching approximately 700oC and above. The DBA developed TSP™ process, stress relieves the cast iron during the manufacturing process. Unlike any other cast irons, the XG-150 formulation was developed to respond to the TSP process resulting in a rotor that is ideal for heavy duty braking and suitable for motorsport applications.
Fitting Instructions for a Hat Type Disc Rotor
Today’s disc brake systems commonly make some minor noise during normal operation such as whirring and occasionally squeaking. Most of these noises are considered normal. However, what about noises that aren’t considered ‘normal’ such as grinding or scraping?
First we have to determine if the grinding noise is during driving, during brake application, or both. In this article we want to focus on some of the causes of grinding noises during driving when the brakes aren’t being applied, as opposed to grinding when applying the brakes. We’ll save that for another article.
While its rare, this can be the most perplexing of all brake noise issues: Debris caught in the system. Sometimes a small rock, road salt, or other debris can find its way into the braking system or hub area. When this happens, it can get wedged in between the hub or heat shield and the rotor, causing a constant grinding or rubbing noise during driving. Sometimes this can be resolved by rolling the car backwards while applying the brake a few times. This motion can dislodge problematic intruder with little effort. But in the case that this doesn’t fix the issue, the system may have to be disassembled to resolve the problem.
When there is a significant amount of corrosion or rust build up on the rotor faces from the vehicle being stored for an extended time, or highly corrosive wheel cleaners, there can be a period where the brakes will make a rubbing noise until the pads can properly clean the surfaces. This issue usually resolves itself by driving cautiously until the braking surfaces are free of contamination. It is strongly recommended that additional braking distances are used during this period for safety. If this doesn’t resolve itself fairly quickly, then there may be a larger issue at hand.
The spacing between some of the braking components can be very small, so the slightest variation in the alignment of parts can cause problems where parts can make contact with each other. For example, in heavy snow areas when there is a lot of ice and snow that can build up in the wheels, metal heat shields can be damaged or deformed and cause them to come in contact with the rotor or hub. This can also happen in off-road or gravel driving environments. The only way to resolve this is to disassemble the components and either replace, or repair the component that is bent or damaged.
Caliper or pad issues
Grinding noises can be caused by a few different pad or caliper problems. First would be a caliper that is seized or stuck. This can be caused by corrosion or simply due to wear and tear. If a caliper is seized, when the pedal is released, the pad doesn’t pull away from the rotor as it should and can stay in contact with the rotor during driving. Additionally, brake pads that are designed to move freely in the caliper can become seized or can sometimes become dislodged allowing unintended movement causing the pad to come in contact with the rotor when it isn’t supposed to, also resulting in grinding noises. Re-seating the pads with appropriate grease can usually remedy this problem.
The parking brake system can cause grinding issues two different ways. First, and most common is that the parking brake either wasn’t released, or wasn’t released completely. This is the first thing to check when any grinding noises occur, its quick and easy to try again to release the brake to resolve the problem. Secondly, the because the parking brake system isn’t used as often as the primary braking system, the parking brake can be subject to seizing or sticking more often than you might expect. The best bet is to try applying the parking brake and releasing it again in hopes of breaking it loose. If that doesn’t work, a more comprehensive examination may be required.
Generally, these issues we’ve reviewed aren’t cause for alarm, as many of them can be fixed quickly and easily. However, if you are experiencing problems other than these mentioned, or that cant be quickly resolved, DBA USA strongly suggests you have your vehicle checked out thoroughly by a professional. Because the braking system is the most important safety feature of your vehicle.
We put together this short article targeted at beginners, but there is still valuable information here for even the most seasoned car-guy or gal! We’ll review the various types of brake rotor damage like squeaking, cracking, rusting or anything else that may have caught your attention. You may be surprised to find that some things are absolutely normal and not life-threatening.
1. Brake Rotors Rusting
Many non-enthusiasts who are first time car buyers are caught off guard by this and start anxiously lurking forum threads to find answers. The majority of the material that make up your brake rotors is cast iron. Therefore, due to even minor mere oxidation, rust will inevitably develop. This explains why rust will still occur even if you live in the city and only take your car out on weekends. A build up of rust is not life threatening nor is it the cause of your disc brakes squeaking. So doth sweat it if you see some occasional rust developing.
2. Brake Rotors and Brake pedal pulsation
Many of today’s vehicles have brake systems where the disc rotors are a “top hat” design. These designs are generally easier to service but at times, can create some customer dissatisfaction due to brake pedal pulsation during the brake application. Brake pedal pulsation is most often the result of disc thickness variation in the rotor. Disc Thickness Variation (DTV) is the technical term for a rotor that is not uniformly thick. Quality rotors are uniformly thick when new, and will stop the vehicle smoothly. However, due to other potential irregularities in the braking system, variation in the disc thickness can develop over time and eventually lead to brake pedal pulsation. The most common cause of DTV is rust scale or debris between the hub and rotor mounting surfaces, This causes the rotor not to sit flat resulting in excessive runout. This may not be evident once the rotor is removed from the vehicle, since its the hub mating surface that causes the problem.
3. Brake Rotor Cracking
When cracking occurs, your rotors are done, they are unsafe to drive on, and should be replaced immediately. While drilled rotors offer loads of performance braking improvements, they are also more prone to cracking. The best way around this is to invest in well known brands and trusted products that undergo tested and proven methods of manufacturing. Of course there are other causes of rotor cracking but with the quality of DBA rotors, you would have to do an awful lot to induce such damage. Unless you track your car frequently, cracking shouldn’t be an area of concern for you.
4. Brake Rotor Scarring
Scarring generally occurs when metal touches metal, due to an aggressively worn-out brake pad. The result? You get scratching and scarring on the rotor surface that affects the safety of your overall driving experience. The good news is, that this kind of damage can be machined and leveled depending on the degree of damage to your rotors. While repairing versus replacing scarred rotors is a debatable topic, you will find that your mechanic will give you the best possible opinion on the next course of action. He can see it and assess the damage properly, as there is only a limited number of times you can rub down a rotor. All rotors have a minimum thickness that they can be machined down to before needing to be replaced.
People often take brake maintenance for granted but you still should be aware when you need a brake change. It’s vital and can save you plenty in the long run.
Damage to rotor caused by loss of friction material and pad backing plate contacting rotor. (metal to metal)
During the brake disc inspection there are several components you need to check and ensure are working properly. In addition, brakes need too be checked at least twice a year and if you drive substantially more than the average worker’s commute, then you need to do it more often. Inspecting your brake disc will help protect you and your passengers as well as help save money from damage that would otherwise result due to negligence diligent brake maintenance.
Most vehicles brakes today can be inspected without removing the wheels and this is easier on vehicles with alloy rims (some would argue that this is a luxury exclusively to those with alloys). But this should never be a constraint since even if it means jacking up the wheels and checking the brake pads and brake disc’s wear.
First inspect your Disc
Before hopping to do this you need to be aware that the brakes need to cool down before checking, to avoid burning yourself. Brake parts can get extremely hot so don’t attempt this after having been driving. It is best to do this early in the morning or after waiting for 2-3 hours after driving for the brake disc to cool. This is a no-brainer, but you’d be surprised/entertained by how many people burn themselves when handling their vehicles at home. The brake disc should be relatively shiny although it may also have small ridges. But this is quite normal so you don’t need to be alarmed. What you do need to do is feel around for rough spots or irregular grooves developing on the brake disc. If these are visible then you will need a brake disc change to make sure road safety is maintained.
Next Comes inspecting the brake pads
Once again on some vehicles these can also be inspected through the rims but if it’s not clear then just remove the wheel to be sure. Most brake disc pads when new have approx 9-12 mm of friction material visible As long as there is still greater than 3 mm of material showing all round the pad, your brake pads still have life in them. You also need to be mindful that vehicles can experience slight differences in wear on each wheel, so ensure you check both sides thoroughly. If the material is 3mm or less then you need a brake change on your pads. Make sure to change all disc Brake pads together, not just on one wheel.
Just remember, when in doubt, see your trusty mechanic!
Many of today’s vehicles have brake systems where the disc rotors are a “top hat” design; These designs are generally easier to service but at times, can create some customer dissatisfaction due to brake pedal pulsation during the brake application. Brake pedal pulsation is most often the result of disc thickness variation in the rotor. Disc thickness variation (DTV) is the technical term for a rotor that is not uniformly thick.
Quality rotors are uniformly thick when new, and will stop the vehicle smoothly. However, due to other potential irregularities in the braking system, disc thickness variation can develop over time and eventually lead to brake pedal pulsation.
DTV = Pulsating Brake Pedal (and, in extreme cases, severe mechanical vibration through the entire vehicle)
The most common cause of DTV is rust scale or debris between the hub and rotor mounting surfaces, This causes the rotor not to sit flat resulting in excessive runout.
Warping is primarily caused by excessive heat, which softens the metal and allows it to be reshaped. The main causes of overheating are: undersized or over machined brake discs, excessive braking (racing, descending hills/mountains), “riding” the brakes, or a “stuck” brake pad (pad touches disc at all times).
Another potential cause of warping is when the disc is overheated and the vehicle is stopped. When keeping the brakes applied, the area where the pads contact the disc will cause uneven cooling and lead to warping.
Several methods can be used to avoid overheating brake discs. Use of a lower gear when descending steep grades to obtain engine braking will reduce the brake loading.
Also, operating the brakes intermittently ? braking to slower speed for a brief time then coasting will allow the brake material to cool between applications. Riding the brakes lightly will generate a great amount of heat with little braking effect and should be avoided.
High temperature conditions as found in motor racing can be dealt with by proper pad selection, but at the tradeoff of everyday drivability. Pads that can take high heat usually do best when hot and will have reduced braking force when cold. Also, high heat pads typically have more aggressive compounds and will wear discs down more quickly.
Warping can also be caused by improperly torquing the lug/wheel nuts when putting on a wheel.
Warping will often lead to a thickness variation of the disc (DTV). If it has runout, a thin spot will develop by the repetitive contact of the pad against the high spot as the disc turns. When the thin section of the disc passes under the pads, the pads move together and the brake pedal will drop slightly. When the thicker section of the disc passes between the pads, the pads will move apart and the brake pedal will rise slightly. This change causes pedal pulsation.
The thickness variation can be felt by the driver when it is approximately 0.015mm / 0.0006 inch or greater.