Lotus Elise Brake Disc Guide

When it comes to maintaining the performance and safety of your Lotus Elise, S1 Exige, 340R, or even the Vauxhall VX220/Opel Speedster, the humble brake disc plays a pivotal role. Over the years, these vital components have seen significant evolution, driven by cost, performance demands, and technological advancements. Understanding the differences between the various types of brake discs fitted to these iconic vehicles can help you make informed decisions about maintenance, upgrades, and replacements. This guide delves into the history and characteristics of Lotus brake discs, from the innovative Metal Matrix Composite (MMC) to the ubiquitous cast iron, and explores various upgrade options available.

The Original: Metal Matrix Composite (MMC) Discs

The early iterations of the Lotus Elise, specifically from its inception up to VIN 3714, were equipped with Metal Matrix Composite (MMC) brake discs, paired with specific MMC brake pads. The general consensus is that this MMC setup offered excellent brake performance and feel. The primary advantage of MMC discs lies in their use of Adherent Friction. Unlike traditional abrasive friction, where pads wear down the disc, MMC systems work by transferring a small amount of pad material onto the disc surface. This creates contact patches of the same material, leading to a smoother and more efficient braking process. A significant benefit of this system is its longevity under normal use, as the disc material itself experiences minimal wear.

However, MMC discs were not without their drawbacks. The most notable complaint was their performance in wet weather; the initial brake 'bite' was often poor until the discs were dried through application. Lotus did address this to some extent by introducing a splash guard from VIN 2260. Under very heavy usage, such as on a track, the bonds between the pad and disc material could break down faster than they could reform. This could lead to areas of the disc losing their material layer, allowing abrasive friction to score the surface, permanently damaging performance and necessitating disc replacement. For this reason, vehicles used extensively on track or fitted with semi-slick tyres might find traditional setups more suitable.

Another key benefit of MMC discs was their significantly reduced weight, contributing to a decrease in unsprung weight, which is crucial for handling and agility. Sadly, the increased part costs associated with MMC technology forced Lotus to switch to standard cast iron brake discs from VIN 3715 onwards. Sourcing replacement MMC pads has also become increasingly difficult, with Lotus even offering discounted conversions to iron discs for affected customers. While third-party replacement pads are available and can improve wet weather performance, genuine MMC discs are no longer manufactured.

The Workhorse: Standard Cast Iron Discs

Following the discontinuation of MMC discs, Lotus transitioned to standard cast iron brake discs for the S1 Elise from VIN 3715. While initially introduced for cost-saving reasons, these iron discs proved to be more robust under the high temperatures associated with track driving and offered superior wet weather performance compared to their MMC predecessors.

Vented S1 OEM Discs

These discs feature a solid friction surface but are internally vented. This internal venting system works through centrifugal force. As the disc rotates, air is drawn in from the centre and expelled outwards through the vanes and out of the disc's edges. This process enhances cooling, helping to prevent brake fade during spirited driving. The Lotus Part Number for these is A111J0128F.

Cross-Drilled and Vented Discs

Certain performance variants of the S1 Elise, including the Sport 135, Sport 160, Sport 190, and the 111S, were fitted with vented discs that were also cross-drilled. Cross-drilling involves drilling holes through the disc surface, offering several advantages:

• Improved Cooling: The holes allow for more airflow into the internal vanes, further enhancing cooling efficiency.
• Enhanced Pad Cleaning: The edges of the holes help to clean the pad surface, potentially increasing brake 'bite'.
• Gas Dissipation: The holes prevent the build-up of gases between the pad and disc surface, which can reduce braking effectiveness.
• Weight Reduction: Drilling holes reduces the overall weight of the disc, thereby decreasing unsprung mass and rotational inertia.

These cross-drilled and vented discs carry the Lotus Part Number A111J0141F. The Series 1 Exige and the 340R also utilised these same discs.

Series 2 Elise and Exige Discs

The Series 2 Elise models typically came equipped with 288mm vented iron discs. For the Exige S240 and S260 models, an optional upgrade to larger 308mm four-piston AP Racing brakes was available. The S2 discs differ from the S1 iron discs, which were essentially an unconventional size derived from the original MMC design. The S2 discs are of a more standard size, with plain vented versions being standard fitment and cross-drilled versions available as an option. Later S2 models often came with cross-drilled discs as standard.

The design of the S2 discs features longer, curved internal cooling vanes. This revised vane design contributes to increased disc stability and reduces the formation of 'hot spots' – areas of concentrated heat that can lead to uneven wear and reduced performance. The hole pattern on cross-drilled S2 discs has also been optimised to complement these new vane arrangements. Importantly, the S2 discs are not 'handed', meaning the same disc can be used on both the left and right sides of the car. The cooling airflow is primarily dictated by the pressure differential between the disc centre and rim, rather than the direction of rotation.

It's worth noting that some brake noise is to be expected with performance setups, and there are known fixes for brake pads potentially banging within the calipers.

Vauxhall VX220/Opel Speedster Discs

The Vauxhall VX220 and Opel Speedster share many similarities with the S2 Elise, including the 288mm disc size. However, there are key differences:

• Hubs: They use a 5-stud hub pattern.
• Centre Bore: The centre bore is larger.
• Offset: A slightly different offset (approximately 1-2mm) is used due to the VX220's different bearing pack, although the uprights are identical to the S2.
• Thickness: While similar in overall thickness to S2 discs (25mm vs. 26mm), VX220 discs have a much thicker friction surface and consequently a smaller air gap between the disc surfaces.

These differences, particularly the thicker friction surface, make VX220 discs significantly heavier than S2 discs (around 750g to 1kg each). While the thicker surface might offer a slight increase in heat capacity, it can also make heat dissipation more challenging. A significant advantage of VX220 discs is their origin from common GM parts (like Vauxhall Vectra V6 2.5 front discs), making them widely available and very affordable from standard car parts retailers.

Lotus Europa Disc Brakes

Information on Lotus Europa disc brakes suggests they utilise 288mm vented discs and are compatible with ABS systems. Reports indicate that these discs are the same as those used on the VX220, and the Europa shares the same hubs as the VX220.

Elise Upgrade Options

For those seeking enhanced braking performance, a variety of upgrade options are available:

Lotus Motorsport Upgrades

Lotus Motorsport offered several upgrade paths:

• Brake Bias Valve: Allows for adjustment of the front-to-rear brake balance, often seen on models like the Elise S2 Sport 190 and VX220 Sprint (Lotus Part Number: ALS1J6012F).
• Brake Master Cylinder: (Lotus Part Number: ALS1J6010F) Available through specialist suppliers, these are often sourced from AP Racing.
• Bolt-on Caliper and Disc Kits: These kits typically include AP Racing four-pot alloy calipers with performance pads (e.g., Pagid RS14) and alloy bells with discs.

Lotus Motorsport also offered a more comprehensive kit featuring 2 x AP 4-pot alloy calipers with Pagid RS14 pads and 2 x alloy bells with discs. These kits offered upgraded performance, with different configurations for fast road use (Ferodo pads, single-piece discs) and track use (Pagid pads, two-piece discs). The track-focused kits often featured larger 310mm diameter discs and were designed for specific wheel fitments. These kits were generally recommended for track use only and often required the use of braided brake hoses for optimal performance.

Aftermarket Specialists

Several specialist companies offer performance brake upgrades:

• EliseParts.com: Offers aluminium-bell discs for S1 and S2 models. These feature custom bells with OEM rotors (e.g., Hispec/EBC) that can start at 26mm thickness. They are highly regarded for track and race use, especially when paired with Pagid RS14 pads, offering good durability for endurance racing.
• Elise-Shop.com: Provides bespoke motorsport brake discs, often cross-drilled and grooved, designed for optimal performance with specific pads like Pagid RS42 or RS14. These are recommended for heavy track day use and racing. They also offer a grooved-only version suitable for fast-road and trackday use.
• EBC Brakes: Offers a range of performance discs. Their Sport range features drilled and slotted designs with special disc alloys and dimple hole construction for improved cooling and pad cleaning. EBC also offers Ultimax discs, which are designed for quieter braking and feature corrosion-resistant coatings, though the effectiveness and longevity of the coating can vary. EBC also provides a wide range of compatible brake pads.
• HiSpec Motorsport: Specialises in high-performance braking systems, offering a range of calipers and discs.
• DBA (Disc Brakes Australia): Offers robust 4000 and 5000 series rotors, available in both one-piece and two-piece configurations, with various sizes to suit different Lotus models.

Common Questions

Pads Sticking to the Disc

A common observation, particularly with the S1 Elise's un-servoed brakes, was the tendency for brake pads to stick to the discs. This was often a byproduct of using higher 'grab' pads to improve initial bite. In damp or humid conditions, this sticking can occur relatively quickly, sometimes within a couple of hours. While it can lead to a noticeable 'clunk' when pulling away, especially after washing the car or in wet weather, it's generally considered a characteristic of the system rather than a fault. It's a phenomenon known as TADTS (The Almighty Damn Thing Sticking), a common occurrence in the automotive world.

Brake Disc Terminology Explained

• Vented Discs: Feature internal vanes or air channels to facilitate cooling.
• Cross-Drilled Discs: Have holes drilled through the disc surface to improve cooling, gas dissipation, and pad cleaning.
• Grooved/Slotted Discs: Have grooves or slots machined into the surface to help expel gases, heat, and debris, and to maintain a flatter pad surface.
• Two-Piece Discs: Consist of a separate iron braking surface (rotor) and an aluminium or steel 'bell' or 'hat'. This design reduces weight and allows for better thermal management as the bell can dissipate heat more effectively.
• Adherent Friction: A braking mechanism where pad material transfers to the disc surface, creating a bond that generates friction.
• Abrasive Friction: The traditional method where the pad material wears away the disc surface to create friction.
• Unsprung Weight: The mass of the vehicle not supported by the suspension, including wheels, tyres, brakes, and hubs. Reducing unsprung weight improves handling and ride quality.

Choosing the right brake discs for your Lotus or VX220/Speedster depends on your driving style and priorities. For everyday road use, standard vented iron discs often suffice. For more spirited driving or occasional track use, cross-drilled or grooved discs from reputable aftermarket suppliers can offer significant improvements. For dedicated track or race applications, high-performance two-piece kits with specialised pads are usually the best option. Always ensure that any brake components you choose are compatible with your specific vehicle model and intended use.

Table: Brake Disc Types and Characteristics

Frequently Asked Questions

Are MMC brake discs still available?

No, genuine MMC brake discs are no longer manufactured. They were phased out by Lotus due to cost reasons.

Which brake discs are best for track use?

For track use, cross-drilled and vented discs, or two-piece performance aftermarket discs from brands like EBC, EliseParts, or Elise-Shop are generally recommended due to their superior cooling and heat dissipation capabilities.

Why do my brake pads stick to the discs?

This is often due to the pad material transferring to the disc surface and bonding slightly, especially in damp conditions or after washing the car. It's usually harmless but can cause a clunking noise on initial movement.

Can I fit S2 Elise discs to an S1 Elise?

Direct fitment is unlikely due to the different hub and disc dimensions between the S1 and S2 models. Adapters or specific upgrade kits would be required.

What is the advantage of two-piece brake discs?

Two-piece discs offer reduced unsprung weight and improved thermal management, as the separate bell can dissipate heat more effectively than a solid one-piece disc.

Disclaimer: This information is compiled from various sources and is intended as a guide. Always consult with a qualified mechanic or refer to your vehicle's specific service manual before undertaking any maintenance or upgrades.