Wilwood publishes more than a dozen friction compounds, and the part number tells you which one you are holding. In 150-30-7416K the 30 is the compound and the 7416 is the plate shape. This guide covers what each compound does, what it is legal for, and which rotor materials it can safely run against.
Every characteristic, application and rotor-compatibility statement below comes from Wilwood’s own published data for that compound.
How to read a Wilwood pad part number
| Part number structure | ||
|---|---|---|
| 150-30-7416K | 150 is a pad, 30 is the BP-30 compound, 7416 is the plate shape | Standard racing pad |
| 150-Q-6617K | Q is the BP-Q compound | Letter compounds sit in the same position |
| 15E-8306K | 15E is PolyMatrix E | PolyMatrix uses a 15A / 15B / 15E / 15H / 15Q prefix and the plate is not in the number |
PolyMatrix part numbers are the exception worth remembering: the plate shape does not appear anywhere in the number, so 15E-8306K gives no hint that it is a 5310 plate. Every PolyMatrix listing on this site names its plate in the title for that reason.
The BP series, coldest to hottest
The BP numbers run roughly in order of heat capacity and friction, but they are not a simple ladder. BP-22 and BP-Q are ceramic street compounds that sit outside the racing progression.
| Compound | Friction | Street legal | Rotor materials | Typical use |
|---|---|---|---|---|
| BP-10 | Medium | Yes | Iron, steel | High performance street, muscle cars, drag, light dirt |
| BP-20 | Medium | Yes | Iron, steel, stainless | Track-oriented street cars, autocross, track day. Baseline track compound |
| BP-22 | Medium, ceramic | Yes | Iron, steel, stainless | Street performance, autocross, street and strip, towing. Lowest dust and noise |
| BP-Q | Medium, ceramic | Yes | Iron, steel | Show cars, street rods, muscle cars, truck and SUV kits |
| BP-28 | Medium to medium-high | Racing only | Titanium, stainless, iron, steel | Sprint and midget, dirt late model, open wheel modified, lighter road race cars |
| BP-30 | High | Racing only | Iron, steel, stainless, super alloy, titanium | Road course, heavy duty pavement oval, club sport, cars with ABS |
| BP-35 | High | Racing only | Iron, steel | Road course, pavement oval, off-road, dirt late model, open wheel modified |
| BP-40 | High, aggressive bite | Racing only | Iron, steel, stainless, super alloy, titanium | Road course, pavement oval, dirt all classes, off-road |
| BP-45 | High, strong cold bite | Racing only | Iron, steel | All race vehicles. The most forgiving of the high-friction compounds from cold |
Choosing between BP-30, BP-35, BP-40 and BP-45
These four are the road racing compounds and the choice between them is the question we are asked most. They separate on initial bite and cold performance rather than outright heat capacity.
- BP-30 has a medium initial response that builds with temperature, very high fade resistance and low wear when hot. It is the most linear of the four and the easiest to modulate. Wilwood also lists it as the suggested replacement for PolyMatrix H and for the CM composite metallic compound.
- BP-35 offers similar friction to BP-30 with better low and medium temperature response, smooth release and low to medium wear. Iron and steel rotors only.
- BP-40 has an aggressive initial response and good cold bite, with low wear under sustained heat. Choose it when you want the pedal to bite immediately rather than build.
- BP-45 has the strongest cold friction of the group, rising smoothly as the rotor heats. Wilwood lists it simply as suitable for all race vehicles. Iron and steel rotors only.
A practical way to decide: if your complaint is that the pedal feels wooden on the first lap, move toward BP-45 or BP-40. If your complaint is that the car is hard to trail-brake smoothly, move toward BP-30 or BP-35.
PolyMatrix compounds
PolyMatrix is Wilwood’s premium race friction line. It carries the highest prices in the pad range and is available on far fewer plate shapes than the BP series.
| Compound | Friction | Street legal | Rotor materials | Typical use |
|---|---|---|---|---|
| PolyMatrix A | Ultimate high friction, very aggressive bite | Racing only | Iron, steel | Road course, pavement oval, dirt all classes. Immediate response from cold |
| PolyMatrix B | Medium-high | Racing only | Iron, steel | Road course, pavement oval, dirt, off-road |
| PolyMatrix E | Medium | Yes | Iron, steel | Performance street, autocross, track day, low temperature drag with steel rotors |
| PolyMatrix H | High | Racing only | Iron, steel | Road course, pavement oval, dirt, off-road. Wilwood suggests BP-30 as the replacement |
| PolyMatrix Q | Medium, ceramic | Racing | Aluminium, stainless | The compound for aluminium and stainless rotors. Low rotor wear and good feel |
Specialist compounds
| Compound | What it is for | Rotor materials |
|---|---|---|
| CM composite metallic | High friction with smooth initial response, formulated specifically for stainless steel rotors, high fade resistance. Wilwood suggests BP-30 as the replacement | Stainless, steel, iron, super alloy, titanium |
| PCM carbon ceramic | Medium to medium-high friction for vented carbon-ceramic rotors on high performance street and strip, drag and track day cars | Carbon ceramic |
| Purple | Composite metallic for high-temperature durability on aluminium and other low-conductivity alloy rotors. Long wear and high fade resistance in sustained heat. Sprint cars | Aluminium, steel, stainless |
| SmartPad TX1 | Medium-high friction with flat torque from 100 to 1200 degrees F and low temperature response. Developed as an armoured vehicle pad, also used off-road | Iron, steel |
Rotor material is a hard constraint
This is the part of compound selection that is not a matter of preference. Running the wrong friction material against your rotor material destroys rotors and can cost you the brakes.
- Aluminium rotors take only Purple or PolyMatrix Q. Nothing in the BP series is formulated for them.
- Carbon ceramic rotors take only PCM.
- Titanium rotors take BP-28, BP-30, BP-40 or CM. Note that Wilwood rates BP-28 as medium-high wear on titanium.
- Stainless steel rotors are best served by CM, which is formulated specifically for them. BP-20, BP-22, BP-28, BP-30, BP-40, Purple and PolyMatrix Q are also listed as compatible.
- Iron and steel rotors take everything except Purple, PolyMatrix Q and PCM.
Racing only means racing only
Wilwood marks BP-28, BP-30, BP-35, BP-40, BP-45, CM and PolyMatrix A, B and H as racing only, not for street use. That is not a warranty disclaimer. These compounds have poor cold friction by design, and a car that has been sitting in traffic will not stop the way the driver expects.
If the car sees any road use, the compounds cleared for street are BP-10, BP-20, BP-22, BP-Q and PolyMatrix E.
Bedding in
Wilwood supplies most racing pads unbedded, and the pad data flags whether a given part number ships pre-bedded. A new pad on a new rotor needs a bedding cycle before it is trusted at speed. Run a series of progressively harder stops from moderate speed without coming to a complete halt, then a cooling lap without dragging the brakes.
Skipping the bed-in is the most common cause of a new high-friction pad feeling worse than the worn one it replaced.
Compound availability varies by plate
No plate shape carries every compound. The dense plates carry nine or ten, and many carry only one. Before settling on a compound, check that it exists for your plate. The Wilwood plate, caliper and thickness guide lists what is available on each shape, and every plate listing on this site shows its full compound range in one place.
Document details
| Document type | Guide |
| Brand | Wilwood |