08/06/2012
For many BMW E9x owners, the quest for enhanced performance often leads to the braking system. While the question of whether F30 brakes can be directly swapped onto an E9x chassis is a common one, the focus for optimal stopping power and value often shifts to dedicated upgrade paths tailored for the E9x platform. Understanding the various options available, from aftermarket kits to OEM alternatives, is crucial for making an informed decision that balances performance, cost, and aesthetics.
Improving your vehicle's braking capability isn't just about track performance; it's a significant safety upgrade for daily driving, especially if you've increased your car's power output. A robust braking system provides confidence, reduces stopping distances, and offers better fade resistance during spirited driving or emergency situations. When considering an upgrade, it's vital to look beyond just the caliper colour and delve into the technical specifications, such as disc size, caliper design, and pad compounds.
The 'Bang for Buck' Performance Upgrade: Willwood Kit
One of the most highly recommended and cost-effective performance brake upgrades for the BMW E9x series comes in the form of a Willwood kit, often available through specialists like Revolution Brakes. This particular upgrade package is designed to significantly boost your E9x's stopping power by allowing you to fit larger 348mm brake discs, which are the same size as those found on the higher-performing 335i models. This larger disc size provides a greater swept area for the brake pads, leading to improved heat dissipation and more consistent braking performance under demanding conditions.
Beyond the enhanced functionality, these Willwood kits often offer customisation options, such as various caliper colours, for a relatively small additional cost. This allows owners to personalise their vehicle's appearance while upgrading a critical component. The appeal of such a kit lies in its ability to deliver a substantial performance leap without breaking the bank, presenting a compelling argument against more expensive, less effective alternatives.
Critiquing the BMW OEM 6-Pot Upgrade
While BMW offers its own performance brake upgrade packages, not all are created equal, especially when evaluated for their value proposition. The OEM 6-pot upgrade, for instance, often receives criticism for what some consider a disappointing return on investment. Despite its more aggressive appearance and multi-piston calipers, this specific OEM package typically only upgrades an E9x to 330mm brake discs. For owners of 335i models, which already come standard with 348mm discs, this OEM upgrade can actually be a downgrade in terms of disc size and, consequently, overall braking potential.
The perception is that while these OEM upgrades 'look good', they may not deliver the tangible performance improvement expected for their price point. This highlights a crucial consideration: always look beyond the initial visual appeal and assess the underlying specifications, particularly disc diameter, which plays a significant role in a brake system's heat capacity and stopping power. Investing in an OEM upgrade that offers smaller discs than your current setup, or only a marginal increase, may not be the most sensible value proposition for serious performance enthusiasts.
Cost-Effective OEM Alternatives for E9x Owners
For E9x owners seeking a genuine performance upgrade without the premium price tag of new aftermarket kits, sourcing used OEM 335i brakes presents an excellent and often overlooked option. As the 335i models feature 348mm discs as standard, acquiring a used set of these calipers and carriers can provide a direct and significant upgrade for other E9x variants that come with smaller brakes. These components can frequently be found on enthusiast forums or online marketplaces for a fraction of the cost of new parts, typically ranging from £300 to £500.
This approach combines the reliability and engineering standards of genuine BMW parts with a highly attractive price point, making it a popular choice for those on a tighter budget but unwilling to compromise on performance. When opting for used parts, always ensure they are in good condition, ideally from a reputable seller, and be prepared to factor in the cost of new brake pads and discs for optimal performance and safety upon installation.
Aesthetics vs. Performance: The Visual Upgrade
Not every brake modification is driven by a desire for increased stopping power. For some, the primary goal is to enhance the visual appeal of their vehicle. In such cases, options like installing cross-drilled rotors and painting existing calipers can achieve a custom look without the significant investment required for a full performance upgrade.
Several brands offer decent quality cross-drilled or slotted rotors that can improve appearance and offer a slight performance edge in wet conditions, including Brakemotive, R1, DBA, and EBC. These range in price, from more budget-friendly options to premium choices. When it comes to painting calipers, while there are certainly 'ghetto looking' paint jobs, a properly executed, professional paint job can dramatically transform the look of your wheels, adding a custom touch that truly stands out. However, it's crucial to remember that these modifications are primarily aesthetic and will not fundamentally alter your car's braking performance in the same way a larger disc or multi-piston caliper upgrade would.
Key Components of a Brake System Upgrade
When considering any brake upgrade, it's important to understand that the system works as a cohesive unit. Upgrading one component often necessitates considering others:
- Calipers: These house the brake pads and press them against the discs. Multi-piston calipers (like 4-pot or 6-pot) distribute pressure more evenly across the pad, improving feel and reducing pad taper.
- Discs (Rotors): The rotating surface that the pads clamp onto. Larger diameter and thicker discs can dissipate more heat, reducing fade. Materials and venting designs also play a role.
- Brake Pads: The friction material that converts kinetic energy into heat. Different compounds offer varying levels of bite, fade resistance, and noise. Performance pads are crucial for track use.
- Brake Lines: Often overlooked, braided stainless steel lines can reduce 'sponginess' in the pedal feel by preventing line expansion under pressure.
- Brake Fluid: High-performance brake fluid has a higher boiling point, essential for preventing fluid fade during heavy braking.
Installation and Bedding-In
Once you've chosen your upgrade, proper installation is paramount. While some mechanically inclined individuals might attempt a DIY installation, for critical safety components like brakes, professional installation is highly recommended if you're not fully confident. Incorrect installation can lead to dangerous brake failure. After installation, a crucial step often overlooked is the 'bedding-in' process. This involves a series of controlled stops that transfer a thin layer of brake pad material onto the disc surface, creating optimal friction and preventing judder. Failing to properly bed-in new brakes can significantly reduce their effectiveness and longevity.
Wheel Clearance and Legalities
A common issue with larger brake upgrades is wheel clearance. Bigger calipers and discs may not fit inside your existing wheels, potentially requiring spacers or new wheels with different offsets. Always check compatibility before purchasing. Furthermore, significant modifications to your vehicle, including brake upgrades, should be declared to your insurance provider. Failure to do so could invalidate your policy in the event of an accident. It's also wise to be aware of any local vehicle inspection regulations regarding modified braking systems.
Comparative Overview of E9x Brake Upgrade Options
| Upgrade Type | Pros | Cons | Typical Disc Size | Est. Cost (GBP) | Primary Benefit |
|---|---|---|---|---|---|
| Willwood Kit (Revolution Brakes) | Excellent performance for value, customisable colours, significant upgrade over stock. | Higher initial cost than used OEM, may require specific wheel clearance. | 348mm | £800 - £1200+ | Performance & Value |
| BMW OEM 6-Pot Upgrade | Genuine BMW part, good aesthetics, potential for improved pedal feel. | Poor value for money, often only 330mm discs (downgrade for 335i). | 330mm | £1500+ | Aesthetics & Brand |
| Used 335i Brakes (OEM) | Cost-effective performance, genuine BMW quality, significant upgrade for non-335i E9x. | Requires sourcing, condition varies, may need new discs/pads. | 348mm | £300 - £600 | Performance & Budget |
| Cross-Drilled Rotors & Painted Calipers | Enhanced aesthetics, relatively low cost. | Minimal performance gain, painting quality varies. | Stock size | £100 - £400 | Aesthetics |
Frequently Asked Questions About E9x Brake Upgrades
Q: Will F30 brakes fit my E9x directly?
A: While the question of direct F30 brake compatibility on an E9x is common, the information available often points to dedicated E9x-specific upgrade paths for optimal fitment and performance. The provided insights focus on proven solutions for the E9x chassis, such as Willwood kits or used 335i brakes, rather than a direct F30 swap.
Q: Do I need to upgrade my brake lines and fluid?
A: For significant brake upgrades, especially those involving larger calipers and discs, upgrading to braided stainless steel brake lines and high-performance brake fluid is highly recommended. This ensures consistent pedal feel and prevents fluid fade under heavy braking, complementing your new hardware.
Q: How important is brake pad choice?
A: Very important. Brake pads are a critical component of your braking system. Different compounds are designed for different purposes, from quiet daily driving to aggressive track use. Matching your pads to your driving style and disc material is crucial for optimal performance, longevity, and noise levels.
Q: Will upgrading my brakes affect my car's handling?
A: Larger brake components can add unsprung weight, which theoretically could affect handling, but the performance benefits in stopping power and fade resistance typically far outweigh this. The improved confidence and control offered by better brakes often enhance the overall driving experience, especially in performance driving scenarios.
Q: How long do upgraded brakes last?
A: The lifespan of upgraded brakes depends heavily on driving style, quality of components, and proper maintenance. Performance pads and discs designed for aggressive use may wear faster than standard components. Regular inspection and timely replacement of worn parts are essential.
Conclusion
Choosing the right brake upgrade for your BMW E9x involves a careful balance of performance goals, budget, and aesthetic preferences. While direct F30 brake swaps are a topic of discussion, the most tried-and-tested methods for enhancing your E9x's stopping power revolve around purpose-built aftermarket kits like the Willwood system or savvy OEM solutions like sourcing used 335i brakes. These options offer tangible performance benefits, particularly with their larger 348mm discs, delivering true bang for your buck compared to some less effective OEM alternatives. Always prioritise safety and proper installation, and remember that a well-chosen brake upgrade is one of the most impactful modifications you can make to your E9x, enhancing both its capabilities and your driving enjoyment.
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