StopTech Stage 2 Brake Upgrade Audi A4 (B5) 2/99 -2001

Stoptech Stage 2 Brake Upgrade includes Centric Posi Quiet Brake Pads, StopTech Stainless Steel Front Brake Lines, StopTech slotted front and rear rotors, and three bottles of Motul RBF600 synthetic brake fluid. A stage 2 brake upgrade kit will fit your stock calipers, and is an excellent choice for the enthusiast whose rotors are nearing the end of their service life, the StopTech Stage 2 kit includes all the components and benefits provided by the Stage 1 kit, but adds value through the addition of direct replacement slotted rotors at all four corners.

About Centric Posi Quiet Brake Pads Posi Quiet pads from Centric Parts offer the solution to dirty rims, and noisy brakes. Posi Quiet Pads use technology which perform with the same quality of stock pads or even better, while making almost no dust or noise. All Posi Quiet brake pads are manufactured using the same positive molding process utilized by OE (Original Equipment) suppliers. These pads solve the main problems with other brake pads such as noise and vibration. Centric recognized these issues and ensures proper fitment in the caliper virtually eliminating noise associated with pad vibration. Eliminate dust and dirt on your rims No Noise from your brakes Optimum braking performance for SUVs, and trucks OEM fitment

About StopTech Stainless Steel Brake Lines StopTech Stainless Steel Brake Lines improve pedal feel and reduce the amount of time between applied pedal pressure and actual deceleration by preventing expansion. This provides a quicker pedal response, and allows the driver to maintain consistent brake pressure and precision brake modulation. StopTech Stainless Steel Brake Lines are 100% DOT compliant and can withstand pressures of 4500 PSI. StopTech brake lines consist of a Teflon inner line that is covered with a layer of stainless steel woven braid. The Teflon tube is resistant to expansion while under pressure and will not degrade from being exposed to brake fluid.

StopTech Slotted Rotors StopTech SportStop Slotted Rotors will fit your vehicles stock calipers and provide increased stopping power over OE. Slotted rotors add more "bite" to your brakes, and prevent your brake pad from glazing. Quality is ensure because SportStop Slotted Rotors are manufactured to meet or exceed factory rotor specifications.

Part Number Reference Guide

Stainless Steel Brake Lines Q&A

by James Walker, Jr. of scR motorsports        

Why are flexible brake hoses used in the first place?

From the factory, nearly every production passenger car has short, flexible hoses that run from the fixed, hard metal brake tubes to the calipers (or wheel cylinders as the case may be). These flexible hoses are necessary because the wheel ends are free to move relative to the body of the vehicle. Inflexible tubes would not allow for the articulation of the wheel ends without subsequent failure.

What are OEM hoses made from?

Typically, OEM hoses contain a compliant polymeric inner hose to transmit brake fluid pressure from the brake tubes to the caliper. While the polymeric tube itself does a good job of withstanding attack from the brake fluid, it must be protected from the outside world and is consequently wrapped (overmolded) with a thick, rubber coating. Hollow fasteners at one or both ends of the hose provide a direct flow path and a leak-free connection system.

So how are Stainless Steel lines different?

Stainless Steel lines (they are actually hoses, but we'll use the common term “lines” from this point forward in this FAQ) are similar to OEM hoses in function, but differ greatly in execution. Unlike OEM hoses, SS lines incorporate a low-compliance Teflon inner hose. In addition, instead of covering the Teflon with overmolded rubber a woven braid of Stainless Steel strands is placed over the hose for protection. As with an OEM hose, the ends are terminated with hollow fasteners to allow for the leak-free passage of brake fluid.

So why is that better than the OEM rubber design?

Stainless Steel lines provide a number of benefits as compared to their OEM rubber overmolded counterparts.

1. The SS braid provides superior protection from flying roadway debris.
2. The SS braid and Teflon hose reduce expansion during pressurization.
3. They provide the race car look.

I understand the protection benefit, but can you explain the reduced expansion benefit?

Any time that an object is subjected to internal pressure, it expands. The amount of expansion will be proportional to the amount of pressure present and the rigidity of the holding structure. In the case of brake hoses, we are subjecting Teflon to internal pressures as high as 3000PSI. Because the Teflon is relatively flexible (which makes it ideal for the job in one regard), it will expand under these conditions. This expansion creates additional fluid volume in the hydraulic circuit which is felt by the driver as a soft or mushy pedal.

Rubber overmolding does little to reduce expansion under pressure, as rubber is also a relatively flexible material. A woven braid of Stainless Steel, however, can greatly increase the rigidity of the hose under pressure while still allowing adequate flexibility for wheel end movement. In many cases, this reduced expansion can be felt by the driver as a firmer or more responsive brake pedal.

In addition, the reduced compliance will result in a faster transient response of the brake system. In other words, the time from the driver hitting the brake pedal until deceleration is generated will be decreased by a small amount. The benefit will vary based on each individual application, but in general overall deceleration can be attained more quickly, resulting in slightly shorter stopping distances.

What impacts will SS lines have on my vehicle's P-T (pressure vs. torque) relationship?

None. Because brake lines and hoses do not affect the torque generated at the wheel end, the P-T relationship remains unchanged when SS lines are installed. Only changes to a vehicle's caliper, rotor, or brake pad coefficient of friction will impact the P-T relationship.

Well then, will SS lines impact my vehicle's P-V (pressure vs. volume) relationship?

Absolutely. Because SS lines are much less compliant than their OEM counterparts, the P-V relationship will be reduced to some degree (less volume will be required at a given pressure). This is exactly the reason that a car equipped with SS lines has a firmer brake pedal.

However, because the P-T relationship remains unchanged with SS lines, the impact to ABS, TCS, and other brake control systems is typically negligible. Our own BBK kit testing indicates that most ABS, TCS, and other brake control systems are robust to the small changes affected by the addition of SS lines. On the other hand, testing at StopTech (and at major OEMs as well) has shown that while decreases in the P-V relationship typically are invisible to SS lines, increases in the P-V relationship are not (as would be found with an inappropriately-sized BBK).

In summary, because SS lines and a properly sized and balanced BBK only serve to reduce the P-V relationship, we have time and time again demonstrated appropriate system integration with these products. Our in-house testing allows us to make this statement for every platform we service.

Will I feel a difference on my car if I install SS lines?

The amount of perceived difference will vary by each car's individual design, age, and usage. Those cars with a significant amount of flexible OEM line or those that have seen years or use and aging will typically display a more dramatic improvement in pedal feel than new cars with shorter lines.

What is the difference between lines that are “DOT compliant” and “DOT approved”?

The United States Department of Transportation (DOT) has established numerous standards for automotive components and subsystems. The regulation for brake hoses happens to be FMVSS106. In this document, anything and everything pertaining to automotive brake hoses has been laid out in gory detail – at least, those things important to the federal government.

If a manufacturer claims their SS lines are “DOT compliant”, it means that their SS lines have passed all FMVSS106 requirements, and they have submitted the test data to the government for official certification. This does not mean they are acceptable for use on your car, but it does mean they pass the government minimum standards.

Another term you may hear in this context is “DOT approved.” However, the DOT is not in the business of actually approving or disproving compliance – they don't typically run any tests on aftermarket components themselves. Under these circumstances, one can only surmise that these manufacturers are trying to state that their lines are actually “DOT compliant”, but it never hurts to ask before you buy.

So, do I need to use only DOT compliant SS lines on my car?

Not necessarily. The DOT requirements must be met in full for official government approval, so even if a SS line passes every performance test but is labeled with the wrong type of tag (or something equally trivial) it would fail certification. While this might mean something to an auto manufacturer or assembly plant, it is meaningless to the performance enthusiast.

All the DOT compliance means is that the lines have passed a minimum set of government standards which may or may not be important to you. Does this mean that DOT compliant lines are the best for your car? Not necessarily, but the certification should indicate that the manufacturer understands the product and is trying to hold itself to a certain standard.

Why do some SS lines have a clear plastic covering?

Under certain conditions, dirt and other abrasive contaminants can find their way between the SS braid and the Teflon inner hose. Over time these contaminants can be ground into the Teflon line to the point that a leak can develop. Naturally, a leak in the brake system is never a good thing.

Some manufacturers have taken the extra step to cover the SS braid with a polymeric coating to prevent contaminants from working their way into the Teflon liner. While this coating is not necessary for short-term longevity, hoses without the coating should be inspected and replaced on a more frequent basis.

Why do some SS lines have plastic molded over the end fittings?

Some SS line manufacturers have adopted the practice of molding a semi-rigid polymer over the fittings at either or both ends of the line. These features act as a strain relief for the SS braid where the fitting is secured to the line. In some cases, lines without these features can fail certain dynamic portions of FMVSS106, as the SS braid can wear itself into the Teflon line where it is secured to the end fitting.

Do I need to take any special precautions when installing my SS lines?

In general, no. The most important thing to note is that the routing of the SS line should match either the original stock routing or the instructions included for a new routing (if applicable). Because the SS braid will eventually wear through just about anything (once the protective outer layer is worn away), be sure that there is adequate clearance to all other moving parts under conditions of full wheel travel and full steering.

It should also be mentioned that after installation care should be taken to examine your SS line routing to ensure that the line is not stressed when the wheels are turned to full lock. This is best done with the wheel hanging at full droop to amplify any routing concerns. Of course the line should never come in direct contact with any part of the tire, but the line should not be pulled radially with respect to the overmolded end fittings either.

How to Bleed Brakes – The Right Way

by John Comeskey of SPS and James Walker, Jr. of scR motorsports        

The role of the brake fluid within the braking system is to transfer the force from the master cylinder to the corners of the car…and a vital characteristic of brake fluid that allows it to perform its task properly is its ability to maintain a liquid state and resist compression. In order to keep the fluid in top condition, many enthusiasts have been taught to “bleed their brakes” but many have never stopped to ask the question “why?”

Why Bleed the Brakes?

The term "bleeding the brakes" refers to the process in which a small valve is opened at the caliper (or wheel cylinder) to allow controlled amounts of brake fluid to escape the system. (When you think about it, "bleeding" may appear to be a somewhat graphic term, but it aptly describes the release a vital fluid.)

We bleed the brakes to release air that sometimes becomes trapped within the lines. Technically, "air" only enters the lines if there is a compromise of the system's sealing (as when flex lines are removed or replaced), because when fluid boils, it will instead create "fluid vapor." Vapor in the brake fluid, like air, will create an efficiency loss in the braking system. However, for the sake of simplicity we use the term "air" throughout this article to describe both air and fluid vapor.

When air (or vapor) becomes present within the lines, it creates inefficiencies within the system because, unlike liquid, air can be compressed. So when enough air fills the lines, input at the pedal merely causes the air to compress instead of creating pressure at the brake corners. In other words, when air is present within the system, the efficiency and effectiveness of the braking system is reduced. Usually, a small amount of air within the brake system will contribute to a "mushy" or "soft" pedal (since less energy is required to compress the air than is required to move fluid throughout the brake lines.) If enough air enters the brake system, it can result in complete brake failure.

So how does air enter the lines in the first place? Sometimes, it can be the result of a service procedure or an upgrade – such as replacing the stock flex lines with stainless steel braided lines. But often it is the result of high temperatures that cause brake fluid components to boil, thus releasing gasses from the boiling fluid into the brake hydraulic system.

Brake Fluid Selection

This leads one to contemplate the type of liquid that is used as brake fluid. In theory, even simple water would work – since, being a liquid, water cannot be compressed. However, it is important to remember that the fundamental function of the braking system is to convert kinetic energy into heat energy through friction. And the reality of this process is that certain parts of the braking system will be exposed to very high temperatures. In fact, it is not uncommon to see rotor temperatures during a race as high as 1200 degrees Fahrenheit – which can raise the temperature of the brake fluid to well over 300 degrees Fahrenheit. Since the boiling point of water is 212 degrees Fahrenheit, it is easy to see that water within the brake system could boil easily – and therefore release gases into the brake pipes – which would reduce the efficiency of the system. (Water would also present a big problem in cold weather if it froze to ice!)

The "obvious" solution to this problem is to utilize a fluid that is less sensitive to temperature extremes. Hence the development of "brake fluid." However, there unfortunately is no such thing as a "perfect" brake fluid. And like most things in the world, the addition of certain beneficial characteristics usually brings tradeoffs in other areas. In the case of brake fluid, we generally must balance the fluid's sensitivity to temperature against its cost and its impact upon other components within the system.

Stated more bluntly, it is possible to reduce a fluid's sensitivity to temperature by varying the ingredients of the fluid. However, certain combinations of ingredients can significantly increase the cost of the fluid and may react with OEM materials to damage seals and induce corrosion throughout the braking system.

The chemical composition and minimum performance requirements of the fluid are generally indicated through a rating such as "DOT3," DOT4," or "DOT5." The DOT-rating itself is assigned after a series of government tests. However, this rating is NOT intended to indicate boiling points, even though higher DOT ratings generally do correspond with higher boiling points. Perhaps more importantly, the DOT rating does indicate the base compound of the brake fluid - which allows manufacturers to specify fluid types which are less likely to react negatively to known materials used within a particular braking system.

The greatest irony about brake fluid, however, is the fact that the chemical compositions that tend to be less sensitive to temperature extremes also tend to attract and absorb water! So even though the fluid itself is unlikely to boil (most glycol-based DOT3 fluids have a "dry boiling point" around 400 degrees Fahrenheit,) the water that it absorbs over time tends to boil easily (at 212 degrees Fahrenheit.) It is this characteristic of absorbing moisture that leads to the measure known as the "wet boiling point." The wet boiling point is the equilibrium boiling point of the fluid after it has absorbed moisture under specified conditions. Because brake fluid will absorb moisture through the brake system's hoses and reservoir, evaluation of the wet boiling point is employed to test the performance of used brake fluid and the degradation in it's performance. (And it is why we still need to bleed the brakes frequently on racecars, even though we use racing fluid that costs upwards of $75 per bottle!) The lesson: do NOT expect to avoid bleeding your brakes just because you bought expensive brake fluid.

As one might guess, "racing" fluids will use relatively "aggressive" chemical compositions which will tend to have higher wet boiling points and higher costs, while the average street fluids will use more conservative compositions which will have lower wet boiling points and lower costs. In some cases – such as a purpose-built racecar – the tradeoffs of using the expensive racing fluid is outweighed by the competitive advantages. But for the average driver – whose driving style is less likely to induce brake temps as high as those seen on the track – the costs of the fluids and potential wear-and-tear factors upon system components may justify the use of a more conservative fluid with a lower wet boiling point.

How-To

So, now that you understand the need behind bleeding your brakes, let us present just one procedure that can be utilized when servicing your own car. Note that unless you are replacing your master cylinder, the procedure is the same whether you have a vehicle equipped with ABS or not…

Supplies Required

You will need the following tools:

· Box-end wrench suitable for your car's bleeder screws. An offset head design usually works best.
· Extra brake fluid (about 1 pint if you are just bleeding, about 3 if you are completely replacing).
· 12-inch long section of clear plastic tubing, ID sized to fit snugly over your car's bleeder screws.
· Disposable bottle for waste fluid.
· One can of brake cleaner.
· One assistant (to pump the brake pedal).

Vehicle Preparation and Support

1. Loosen the lug nuts of the road wheels and place the entire vehicle on jackstands. Be sure that the car is firmly supported before going ANY further with this procedure!

2. Remove all road wheels.

3. Install one lug nut backward at each corner and tighten the nut against the rotor surface. Note that this step is to limit caliper flex that may distort pedal feel.

4. Open the hood and check the level of the brake fluid reservoir. Add fluid as necessary to ensure that the level is at the MAX marking of the reservoir. Do not let the reservoir become empty at any time during the bleeding process!

Bleeding Process

1. Begin at the corner furthest from the driver and proceed in order toward the driver. (Right rear, left rear, right front, left front.) While the actual sequence is not critical to the bleed performance it is easy to remember the sequence as the farthest to the closest. This will also allow the system to be bled in such a way as to minimize the amount of potential cross-contamination between the new and old fluid.

2. Locate the bleeder screw at the rear of the caliper body (or drum brake wheel cylinder.) Remove the rubber cap from the bleeder screw – and don't lose it!

3. Place the box-end wrench over the bleeder screw. An offset wrench works best – since it allows the most room for movement.

4. Place one end of the clear plastic hose over the nipple of the bleeder screw.

5. Place the other end of the hose into the disposable bottle.

6. Place the bottle for waste fluid on top of the caliper body or drum assembly. Hold the bottle with one hand and grasp the wrench with the other hand.

7. Instruct the assistant to "apply." The assistant should pump the brake pedal three times, hold the pedal down firmly, and respond with "applied." Instruct the assistant not to release the brakes until told to do so.

8. Loosen the bleeder screw with a brief ¼ turn to release fluid into the waste line. The screw only needs to be open for one second or less. (The brake pedal will "fall" to the floor as the bleeder screw is opened. Instruct the assistant in advance not to release the brakes until instructed to do so.)

9. Close the bleeder screw by tightening it gently. Note that one does not need to pull on the wrench with ridiculous force. Usually just a quick tug will do.

10. Instruct the assistant to "release" the brakes. Note: do NOT release the brake pedal while the bleeder screw is open, as this will suck air back into the system!

11. The assistant should respond with "released."

12. Inspect the fluid within the waste line for air bubbles.

13. Continue the bleeding process (steps 11 through 16) until air bubbles are no longer present. Be sure to check the brake fluid level in the reservoir after bleeding each wheel! Add fluid as necessary to keep the level at the MAX marking. (Typically, one repeats this process 5-10 times per wheel when doing a ‘standard' bleed.)

14. Move systematically toward the driver – right rear, left rear, right front, left front - repeating the bleeding process at each corner. Be sure to keep a watchful eye on the brake fluid reservior! Keep it full!

15. When all four corners have been bled, spray the bleeder screw (and any other parts that were moistened with spilled or dripped brake fluid) with brake cleaner and wipe dry with a clean rag. (Leaving the area clean and dry will make it easier to spot leaks through visual inspection later!) Try to avoid spraying the brake cleaner DIRECTLY on any parts made of rubber or plastic, as the cleaner can make these parts brittle after repeated exposure.

16. Test the brake pedal for a firm feel. (Bleeding the brakes will not necessarily cure a "soft" or "mushy" pedal – since pad taper and compliance elsewhere within the system can contribute to a soft pedal. But the pedal should not be any worse than it was prior to the bleeding procedure!)

17. Be sure to inspect the bleeder screws and other fittings for signs of leakage. Correct as necessary.

18. Properly dispose of the used waste fluid as you would dispose of used motor oil. Important: used brake fluid should NEVER be poured back into the master cylinder reservoir!

Vehicle Wrap-Up and Road Test

1. Re-install all four road wheels.

2. Raise the entire vehicle and remove jackstands. Torque the lug nuts to the manufacturer's recommended limit. Re-install any hubcaps or wheel covers.

3. With the vehicle on level ground and with the car NOT running, apply and release the brake pedal several times until all clearances are taken up in the system. During this time, the brake pedal feel may improve slightly, but the brake pedal should be at least as firm as it was prior to the bleeding process.

4. Road test the vehicle to confirm proper function of the brakes. USE CAUTION THE FIRST TIME YOU DRIVE YOUR CAR AFTER MODIFICATION TO ENSURE THE PROPER FUNCTION OF ALL VEHICLE SYSTEMS!

How Often do I Need to Bleed My Brakes?

In closing, here are a few rules of thumb to help you to determine the proper bleeding interval for your particular application:

1. Under normal operating conditions, and without brake system modifications, typical OEM braking systems have been designed to NOT require bleeding for the life of the vehicle unless the system is opened for repair or replacement. If you're just driving around town or on the highway to work, there is really no need to bleed! There are a few European vehicles which do recommend replacement on a semi-regular basis for other reasons though, so be sure to check in your owner's manual or at your service center for your particular application.

2. Those who choose to autocross or drive in a sporting manner may choose to upgrade their brake fluid and bleed on an annual basis – this is a good ‘start of the season' maintenance item for low-speed competitors.

3. If your car sees significant amounts of high-speed braking, or if you choose to participate in driver schools and/or lapping sessions, bleeding prior to each event is a sound decision. More intense drivers at these events may choose to skip right past this step and on to #4…

4. Finally, dedicated race cars should be bled after every track session.

Pad and Rotor Bed-In Theory, Definitions and Procedures
Removing the Mystery from Brake Pad Bed-In

by Matt Weiss of StopTech and James Walker, Jr. of scR motorsports

In order for any brake system to work optimally, the rotors and pads must be properly bedded-in, period. This process can also be called break-in, conditioning, or burnishing, but whatever terminology you choose, getting the brakes properly bedded-in and keeping them that way is critical to the peak performance of the entire brake system.

However, understanding why the rotors and pads need to be bedded-in is just as important as the actual process. If one understands what is happening during the bed-in process, they can tailor the process to specific pads, rotors, and/or driving conditions. For this reason, we present this generic bed-in overview pertaining to all brake systems, but follow with links to application-specific bed-in procedures to fit most every set of circumstances.

What is brake pad “bed-in” anyway?

Simply stated, bed-in is the process of depositing an even layer of brake pad material, or transfer layer, on the rubbing surface of the rotor disc. That's it. End of discussion. Ok, not really, but although bed-in is quite basic in definition, achieving this condition in practice can be quite a challenge, and the ramifications of improper or incomplete bed-in can be quite a-a-n-n-o-o-y-y-i-i-n-n-g-g.

Abrasive friction and adherent friction

There are two basic types of brake pad friction mechanisms: abrasive friction and adherent friction . In general, all pads display a bit of each, with abrasive mechanisms dominating the lower temperature ranges while adherent mechanisms come more into play as pad temperature increases. Both mechanisms allow for friction or the conversion of Kinetic energy to Thermal energy, which is the function of a brake system, by the breaking of molecular bonds in vastly different ways.

The abrasive mechanism generates friction or energy conversion by the mechanical rubbing of the brake pad material directly on the rotor disc. In a crystalline sense, the weaker of the bonds in the two different materials is broken. This obviously results in mechanical wear of both the pad and the rotor. Consequently, both pads and rotors are replaced when they are physically worn to their limit and are too thin to endure further service.

The adherent mechanism is altogether different. In an adherent system, a thin layer of brake pad material actually transfers and sticks (adheres) on to the rotor face. The layer of pad material, once evenly established on the rotor, is what actually rubs on the brake pad. The bonds that are broken, for the conversion of Kinetic to Thermal energy, are formed instantaneously before being broken again. It is this brake pad-on-transferred brake pad material interaction on a molecular level that yields the conversion process.

With the adherent mechanism there is much reduced rotor wear as compared to abrasive mechanism, but it's not a free lunch – pads now become the primary wear element in the braking system. And even though rotors are not mechanically worn down with adherent systems, they still will need to be replaced on a regular basis due to cracking reaching a point of failure if they are exposed to intense, repetitive thermal cycling. This is why race teams throw out rotors that are actually as thick or thicker than when they were brand new. It's due to the an adherent brake pad transfer layer!

The all-important transfer layer

As stated above, the objective of the bed-in process is to deposit an even layer of brake pad material, or transfer layer , on the rubbing surface of the rotor disc. Note the emphasis on the word even, as uneven pad deposits on the rotor face are the number one, and almost exclusive cause of brake judder or vibration.

Let's say that again, just so there is no misunderstanding. Uneven pad deposits on the rotor face are the number one, and almost exclusive cause of brake judder or vibration.

It only takes a small amount of thickness variation, or TV, in the transfer layer (we're only talking a few ten thousandths of an inch here) to initiate brake vibration. While the impact of an uneven transfer layer is almost imperceptible at first, as the pad starts riding the high and low spots, more and more TV will be naturally generated until the vibration is much more evident. With prolonged exposure, the high spots can become hot spots and can actually change the metallurgy of the rotor in those areas, creating “hard” spots in the rotor face that are virtually impossible to remove.

Bedding fundamentals

In general, bed-in consists of heating a brake system to its adherent temperature to allow the formation of a transfer layer. The brake system is then allowed to cool without coming to rest, resulting in an even transfer layer deposition around the rotor circumference. This procedure is typically repeated two or three times in order to ensure that the entire rotor face is evenly covered with brake pad material. Sounds easy, right? Well, it can be if you have the proper information.

Because the adherent temperature range for brake pads varies widely (typically 100°F-600°F for street pads and 600°F-1400°F for race pads), each bed-in needs to be application-specific. One could try to generate a one-size-fits-all procedure, but too little heat during bed-in keeps the material from transferring to the rotor face while overheating the system can generate uneven pad deposits due to the material breaking down and splotching (that's a technical term) on to the rotor face.

In summary, the key to a successful bed-in is to bring the pads up to their adherent operating temperature in a controlled manner and keep them there long enough to start the pad material transfer process. Different brake system designs, pad types, and driving conditions require different procedures to successfully accomplish the bed-in. The recommended procedures below should provide you with the information you need to select the bed-in procedure appropriate for your application.

StopTech's Recommended Procedure for Bedding-in Stock-Sized Brake Systems

by Matt Weiss of StopTech and James Walker, Jr. of scR motorsports
      
When a system has both new rotors and pads, there are two different objectives for bedding-in a performance brake system: heating up the brake rotors and pads in a prescribed manner, so as to transfer pad material evenly onto the rotors; and maturing the pad material, so that resins which are used to bind and form it are ‘cooked' out of the pad.

The first objective is achieved by performing a series of stops, so that the brake rotor and pad material are heated steadily to a temperature that promotes the transfer of pad material onto the brake rotor friction surface. There is one pitfall in this process, however, which must be avoided. The rotor and, therefore, the vehicle should not be brought to a complete stop, with the brakes still applied, as this risks the non-uniform transfer of pad material onto the friction surface.

The second objective of the bedding-in process is achieved by performing another set of stops, in order to mature the pad itself. This ensures that resins which are used to bind and form the pad material are ‘cooked' out of the pad, at the point where the pad meets the rotor's friction surface.

The bed-in process is not complete until both sets of stops have been performed.

Bedding-in Street Performance Pads

For a typical performance brake system using street-performance pads, a series of ten partial braking events, from 60mph down to 10mph, will typically raise the temperature of the brake components sufficiently to be considered one bed-in set. Each of the ten partial braking events should achieve moderate-to-high deceleration (about 80 to 90% of the deceleration required to lock up the brakes and/or to engage the ABS), and they should be made one after the other, without allowing the brakes to cool in between.

Depending on the make-up of the pad material, the brake friction will seem to gain slightly in performance, and will then lose or fade somewhat by around the fifth stop (also about the time that a friction smell will be detectable in the passenger compartment). This does not indicate that the brakes are bedded-in. This phenomenon is known as a green fade, as it is characteristic of immature or ‘green' pads, in which the resins still need to be driven out of the pad material, at the point where the pads meet the rotors. In this circumstance, the upper temperature limit of the friction material will not yet have been reached.

As when bedding-in any set of brakes, care should be taken regarding the longer stopping distance necessary with incompletely bedded pads. This first set of stops in the bed-in process is only complete when all ten stops have been performed - not before. The system should then be allowed to cool, by driving the vehicle at the highest safe speed for the circumstances, without bringing it to a complete stop with the brakes still applied. After cooling the vehicle, a second set of ten partial braking events should be performed, followed by another cooling exercise. In some situations, a third set is beneficial, but two are normally sufficient.

Bedding-in Club Race or Full Race Pads

For a typical performance brake system using race pads, the bed-in procedure must be somewhat more aggressive, as higher temperatures need to be reached, in order to bring certain brands of pad material up to their full race potential.

We typically recommend a set of ten partial braking events, from 60mph down to 10mph, followed immediately by three or four partial braking events, from 80mph down to 10mph. Alternately, a set of eleven stops, from 80mph to 40mph, or a set of seven stops, from 100mph to 50mph, would be approximately the same. As with street pads, each of the partial braking events should achieve moderate-to-high deceleration (about 80% of the deceleration required to lock up the brakes and/or to engage the ABS), and they should be made one after the other, without allowing the brakes to cool in between.

Again, depending on the make-up of the pad material, the brake friction will seem to gain slightly in performance, and will then lose or fade somewhat about halfway through the first set of stops. This does not indicate that the brakes are bedded-in, except where race-ready pads are being used. This phenomenon is the same as that which occurs with high-performance or street pads (except that, when race-ready pads are used, they do not exhibit green fade, and they will be bedded-in after just one complete set of stops).

As when bedding-in any set of brakes, care should be taken regarding the longer stopping distance necessary with incompletely bedded pads. This first set of stops in the bed-in process is only complete when the recommended number of stops has been performed - not before. As a general rule, it would be better to perform additional stops, than not enough. The system should then be allowed to cool, by driving the vehicle at the highest safe speed for the circumstances, without bringing it to a complete stop with the brakes still applied.

After cooling the vehicle, a second set of the recommended number of stops should be performed, followed by another cooling exercise. In some situations, a third set is beneficial, but two are normally sufficient.

Racers will note that, when a pad is bedded-in properly, there will be approximately 2mm (0.1 inch) of the pad edge near the rotor, on which the paint will have turned to ash, or the color of the pad will have changed to look as though it has been overheated.

In summary, the key to successfully bedding-in performance brakes is to bring the pads up to their operating temperature range, in a controlled manner, and to keep them there long enough to start the pad material transfer process. Different brake system designs, pad types, and driving conditions require different procedures to achieve a successful bed-in. The procedures recommended above should provide a useful starting point for developing bed-in procedures appropriate to individual applications.

"Well I ordered a full set (front and rear) of the Centric Stop-Tech slotted rotors and Centric Posi-Quiet brake pads for my '05 F-150. After only 35,000 miles the OEM rotors were warped to the point where they could not be safely re-surfaced, according to the Ford dealer.

I ordered everything from Alon at Mod Bargains(Alon@modbargains.com). He was very helpful on the phone and made sure that I had everything that I needed. I was going to get Powerslot rotors, but they did not have them in stock at the time so Alon suggested the Centric StopTech rotors. The total came to $545.20 including the shipping charges. Everything arrived on Monday in 2 very well packaged boxes. Lot's of packing materials to keep things safe. I had a question about shipping and tracking numbers and Mandy in customer service was extremely helpful in getting all of the information to me and following up on my questions.

Unfortunately, I did not have my camera available to take any pictures. The rotors appeared to be of good quality, well machined with no visible sharp edges or partially attached metal shavings. The slots were also quite smooth with no sharp edges. The pad surface of the rotors have a phosphate coating and the rest of the rotor is also covered, not sure if it is a powder coat or just painted. Either way, that should help in keeping down the rust of the outside edges of the rotors.

I don't really know what to say about the pads. They appeared to be of good quality, but I don't really know what to look for when inspecting brake pads. They looked plenty thick enough to me and seemed to be bonded real good. Duh.

I had everything installed by my local mechanic. He also performed the bed-in procedure and flushed/bled the brake fluid. He told me that everything installed by the book with no problems at all. After bedding in the brakes he was impressed with the difference from the OEM brakes but still felt that the brakes were a little soft. Bleeding the system made a big difference in pedal firmness.

The brakes haven't been in for very long, but I already feel like they are much better than the OEM brakes. The original brakes always felt a little soft to me. I had them checked when the truck was at about 2,000 miles and was told by the dealership that they were fine. I got into the habit of pumping once before applying the brakes. That no longer feels necessary.

Everyone I talked with at Mod Bargains was very helpful and knowledgeable of their products. I would have no problem going back to them for any other products that they sell."

                    ~Mark05KR (F150Online.com)
                      New Hampshire