AP Racing by Essex 2001-2006 BMW E46 3-Series 330i 325i Competition Brake Kit (Front CP8350/325mm)
or as low as $270.75/mo with Affirm
AP Racing by Essex
Competition Brake Kit Front CP8350/325mm — BMW E46 3-Series
Purpose-built competition braking for the 2001–2006 BMW E46 3-Series. The CP8350 4-piston fixed caliper paired with 325x32mm J Hook discs saves approximately 15 lbs from the front axle while delivering dramatically improved thermal capacity, modulation, and fade resistance over the OEM sliding caliper system.
Competition Braking
Track-Ready Braking for the BMW E46 3-Series
The OEM E46 braking system uses a single-piston sliding caliper with a 325x25mm one-piece disc and only 40 internal vanes. It was designed for street use and fades quickly under sustained track abuse. This kit replaces it entirely with AP Racing competition hardware engineered for repeated high-heat cycles.
The CP8350 is a 4-piston fixed caliper weighing just 4.8 lbs without pads — a fraction of the OEM 12.34 lb sliding caliper. The 325x32mm 2-piece floating J Hook discs feature 70 directional vanes for vastly superior cooling versus the OEM 40-vane design, and the floating hat construction eliminates disc coning under sustained heat.
The kit uses a universal pad shape compatible with dozens of aftermarket compounds, making trackside pad swaps fast and compound options virtually unlimited. A single 5mm hex bolt is all it takes to change pads — no caliper removal required.
Key Advantages
Engineered Without Compromise
Eight reasons this kit transforms E46 braking performance
4-Piston Fixed Caliper
Four pistons apply force evenly across the entire pad face, delivering consistent clamping force and superior modulation compared to the OEM single-piston sliding design.
Hard Anodized Finish
Hard anodizing grows an extremely durable aluminum oxide layer directly from the base metal via electrical current through an acid bath. Far more resistant to heat degradation than paint or powder coat.
~15 lbs Lighter
Saves approximately 15 lbs of unsprung weight from the front axle versus the OEM E46 330i brakes. Less unsprung mass means faster suspension response, improved grip, and reduced component fatigue.
70-Vane J Hook Discs
75% more internal vanes than the OEM 40-vane disc for dramatically superior airflow and heat evacuation. J Hook slot pattern distributes heat uniformly with more leading edges for consistent bite.
Stainless Steel Pistons
Stainless steel pistons provide a superior thermal barrier that keeps heat out of the brake fluid, maintaining firm pedal feel through extended sessions. No dust boots — high-temp seals designed for track use.
Universal Pad Shape
Compatible with pads from Ferodo, Hawk, PFC, Pagid, Mintex, Carbotech, Endless, and many more. No proprietary pad lock-in — choose from dozens of compounds for any driving style.
Quick Pad Change
A single 5mm hex bolt is all it takes to swap pads — no caliper removal required. Change compounds trackside in minutes between sessions without disturbing brake lines or mounting hardware.
Compact 17" Design
The 325mm disc diameter fits behind 17-inch wheels, allowing you to run lighter, less expensive track wheels. Confirmed fitment with multiple APEX ARC-8 and EC-7R configurations.
Complete Kit
What’s In The Box
- AP Racing CP8350 Calipers (Pair)4-piston fixed, 4.8 lbs each (no pads) — hard anodized finish with stainless steel pistons, anti-knockback springs, and high-temp seals
- AP Racing 325x32mm J Hook Racing Discs (Pair)70 directional vanes — 2-piece floating design with 6061 heat-treated hard-anodized billet aluminum hats, 10-bolt mounting, and 5 spring clips per disc
- Caliper Mounting Brackets & HardwarePrecision-machined brackets with aircraft-quality mounting hardware for direct bolt-on installation
- Spiegler Stainless Steel Brake Lines (Pair)DOT-approved with abrasion-resistant coating and lifetime warranty
- Detailed Installation InstructionsStep-by-step guide for proper fitment and torque specifications
- Not Included: Brake PadsSold separately — 5 compounds available at +$125: DS2500, DS3000, DS1.11, DSUNO, DS3.12. D50 recommended for full disc sweep.
- Not Included: CP8350 Pad Tension ClipOptional add-on for additional pad retention — +$39.90
- Optional: Disc Pre-BurnishingFactory burnishing service — +$100, adds 2–5 day lead time
Technical Data
Specifications
Caliper (CP8350)
4-Piston Fixed CompetitionDisc (325x32mm)
70-Vane J Hook Racing DiscEngineering
Technology Deep-Dive
4-Piston Fixed Architecture
The OEM E46 uses a single-piston sliding caliper that clamps from one side, relying on the caliper bracket to slide and apply force to the inboard pad. This design flexes under heavy use, causing uneven pad wear, inconsistent pedal feel, and progressive fade.
The CP8350 is a fixed, 4-piston design with two pistons per side applying force directly to each pad face. The result is perfectly even clamping, superior modulation, and consistent performance from cold to fully heat-soaked.
Hard Anodized Finish
Paint and powder coat degrade under sustained track heat, bubbling and flaking as temperatures cycle. Hard anodizing passes electrical current through the aluminum caliper body in an acid bath, growing an extremely hard aluminum oxide layer directly from the base material.
The result is an integral protective surface that cannot chip, flake, or separate — significantly harder than the base aluminum with excellent corrosion resistance and thermal stability through thousands of track miles.
Two-Piece Floating Discs
The OEM E46 uses a one-piece disc that cones when heated unevenly — the center heats faster than the outer edge, causing permanent warping, vibration, and accelerated pad taper wear. This is the primary cause of brake judder on track-driven E46s.
The 2-piece floating design uses a separate 6061 billet aluminum hat connected to the iron ring via 10 floating bolts with 5 spring clips. Oblong mounting holes allow radial expansion without distortion, eliminating coning and stress cracking.
70 Directional Vanes
The OEM E46 disc has 40 internal vanes. This disc has 70 directional vanes — a 75% increase in internal airflow capacity. More vanes pump more air through the disc, evacuating heat faster and lowering operating temperatures significantly.
Directional vane design means the vanes are angled to act as a centrifugal pump, actively pulling air through the disc as it rotates. Left and right discs are handed to ensure correct vane direction on each side of the vehicle.
J Hook Slot Pattern
Straight slots create localized cool spots and stress risers that can lead to cracking over time. AP Racing’s J Hook pattern creates a constant pathway of evenly distributed material removal across the entire disc face.
The result is uniform heat distribution, cleaner pad transfer film, and more leading edges per rotation for consistent bite. The J Hook geometry also helps degas the pad surface, sweeping away friction material buildup for cleaner contact.
Stainless Steel Pistons
Stainless steel pistons provide a superior thermal barrier compared to aluminum. They keep heat in the disc and pad where it belongs, rather than conducting it into the brake fluid. This maintains firm pedal feel through extended sessions where aluminum pistons would allow fluid temps to rise and create sponginess.
Anti-knockback springs maintain piston position through corners, eliminating the first-pedal-application drop common after aggressive cornering that pushes the pistons back. High-temp seals replace conventional dust boots for reliable operation at competition temperatures.
How It Compares
Essex/AP Racing vs. OEM E46
| Specification | Essex CP8350 | OEM E46 330i |
|---|---|---|
| Type | 4-Piston Fixed 4x More Pistons | 1-Piston Sliding |
| Weight (no pads) | 4.8 lbs 61% Lighter | 12.34 lbs |
| Piston Area | 49.56 cm² | Single piston |
| Finish | Hard Anodized Track Grade | Paint |
| Pistons | Stainless Steel | Aluminum |
| Pad Change | Single 5mm hex bolt | Caliper removal required |
| Specification | Essex/AP Disc | OEM E46 330i |
|---|---|---|
| Type | 2-Piece Floating Superior | 1-Piece Solid |
| Weight | 15.93 lbs 14% Lighter | 18.55 lbs |
| Diameter | 325mm | 325mm |
| Thickness | 32mm 28% Thicker | 25mm |
| Internal Vanes | 70 Directional 75% More | 40 |
| Hat Material | 6061 Billet Aluminum | Integral cast iron |
| Slot Pattern | J Hook | None |
Pad Compatibility
D43 & D50 Pad Cross-Reference
D50 pads recommended for full disc sweep. D43 and D39 pads physically fit but leave an unswept ring on the disc face.
| Manufacturer | Part Number(s) | Pad Shape |
|---|---|---|
| Ferodo (DS2500, DS3000, DS1.11, DSUNO, DS3.12) | FRP3097 / FRP3116 | D50 |
| Hawk | HB521.800 | D50 |
| PFC | 7751.xx.20 | D50 |
| Pagid | 2205USA | D50 |
| Mintex | 2205 / 2206 | D50 |
| Carbotech | CTW7420 / CTFRP3116 | D50 |
| Circo | MB1680 / MB2660 | D50 |
| Endless | RCP106 / RCP156 | D50 |
| Project Mu | 999 | D50 |
| Raybestos | R701 | D50 |
| Wilwood | 7420 | D50 |
Fitment
Compatible Vehicles
2001–2006 BMW E46 3-Series (non-M3)
Wheel Fitment
Confirmed Clearance
Gallery
Product & Install Images
Spare Parts
Replacement Components
Individual replacement parts available for long-term serviceability
Critical Cautions
D50 pads recommended: D43 and D39 pads fit but leave an unswept ring on the disc face that can cause thermal cracking under heavy track use. Always use D50 pads for track sessions.
No dust boots: These calipers use high-temp seals without dust boots. They are designed for competition use and will allow some dust ingress in street driving conditions.
Brake balance: If upgrading front only, consider using a lower friction rear pad compound to preserve proper front-to-rear brake bias.
Disc sides are handed: CP3870-138GC is the right disc and CP3870-139GC is the left disc. They cannot be swapped side-to-side due to directional vane orientation.
Pro Tips
Brake fluid: Three 500ml bottles recommended for initial install (full system bleed). Use DOT 4 racing fluid rated above 500°F wet boiling point.
New disc prep: Discs have a rust-prevention coating — wash thoroughly with soap and water before installation. Do not use brake cleaner on new discs until coating is fully removed.
Pad bedding: Follow the pad manufacturer’s break-in procedure exactly. Improper bedding causes uneven pad deposits, vibration, and reduced performance.
Spacer quality: When running spacers for wheel clearance, use only hub-centric spacers with extended wheel studs or bolts for safe track use.
Professional Installation
Function Factory Performance offers professional brake service and installation for all AP Racing by Essex brake systems.
Located in Thousand Oaks, California, serving BMWs, Mustangs, Corvettes, McLarens, and more.
Phone: (805) 206-2523
Lifetime Support
Caliper Reconditioning Program
Built to Last — Backed for Life
Essex is AP Racing’s official North American caliper reconditioning center. When your CP8350 calipers need servicing after years of hard use, Essex can restore them to factory specification for approximately $160 per caliper (~$80 labor + ~$60 seals + ~$15 bleed screws).
This is not a warranty service — it is a testament to the quality of AP Racing’s manufacturing that calipers can be rebuilt and returned to active competition rather than discarded.
Expert Guidance
Questions About This Brake Kit?
Our brake specialists can help you choose the right pad compound, verify wheel clearance, and ensure proper installation for your E46. Give us a call or schedule a consultation.
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