22/02/2015
For enthusiasts of the classic MGA, maintaining and upgrading the braking system presents a fascinating blend of historical authenticity and modern performance aspirations. While these charming British roadsters are renowned for their spirited driving experience, their original braking capabilities, though good for their era, can often be a point of consideration for today's roads. This article delves into two key areas of MGA braking: the ingenious 1500 cc front disc brake plate and the ongoing debate surrounding the necessity and implications of fitting a brake booster.
Understanding the MGA 1500 cc Front Disc Brake Plate
Owners of the MGA 1500 cc model often face a particular challenge when contemplating a front disc brake conversion. While disc brakes offer superior stopping power, better fade resistance, and improved wet-weather performance compared to traditional drum brakes, integrating them into the 1500 cc chassis can be complex. This is where the specifically designed 1500 cc MGA front disc brake plate becomes an invaluable component, offering a streamlined solution to a common upgrade dilemma.
This clever plate is engineered to bridge the gap between different MGA and MGB components, allowing for a relatively straightforward conversion without extensive modifications to the vehicle's suspension geometry. Its primary function is to facilitate the mating of an MGB calliper with a 1600 MGA brake disc and a 1600 MGA front hub. The beauty of this specific combination lies in its ability to circumvent the need for adapting MGB suspension components, which would otherwise necessitate complex adjustments to the vehicle's camber and tracking. This means MGA 1500 owners can achieve the benefits of front disc brakes while retaining the original MGA suspension characteristics, preserving the car's handling and feel.
By utilising readily available MGB callipers and 1600 MGA discs and hubs, the plate simplifies the parts sourcing and installation process. This not only saves considerable time and effort but also potentially reduces the overall cost of the conversion, making disc brakes a more accessible upgrade for the 1500 cc model. It's a testament to thoughtful engineering, providing a practical pathway for enhancing braking performance on these beloved classic cars.
| Feature | Drum Brakes | Disc Brakes |
|---|---|---|
| Stopping Power | Good (when cool) | Excellent |
| Heat Dissipation | Poor (prone to fade) | Excellent (less fade) |
| Wet Weather Performance | Can be reduced | Maintained |
| Maintenance Ease | More complex (adjustment) | Simpler (pad replacement) |
| Weight | Generally lighter | Generally heavier (callipers) |
| Pedal Feel | Can be "spongy" | More direct, firmer |
Do MGA Brakes Truly Need a Brake Booster? A Deep Dive
One of the most frequently debated topics among MGA owners is whether to install a brake booster. It's a question that often arises when considering upgrades, but it's crucial to understand what a brake booster actually does – and doesn't do – for your MGA's braking performance.
First and foremost, it's vital to clarify that a brake booster does absolutely nothing to improve the stopping ability of the brakes on your MGA. Whether your MGA is equipped with its original drum brakes or has been upgraded to disc brakes, the fundamental stopping power remains the same. The MGA's braking system, when in good operating condition and not overheated, is remarkably capable; you can lock up the wheels at virtually any speed. So, if your primary goal is to make your MGA stop shorter or more powerfully, a brake booster is not the answer.
What a brake booster *does* achieve is a reduction in the pedal force required for operation. This translates to a lighter, easier pedal feel, which some drivers prefer, especially in heavy traffic or for longer journeys. However, this ease comes at a trade-off: it also reduces tactile feedback, making the pedal feel a little spongy. For some purists, this loss of direct connection to the braking system detracts from the classic sports car experience. Therefore, the decision to install a brake booster is purely a matter of personal choice and driving preference, not a necessity for enhanced safety or performance.
Types of Boosters and Installation Considerations
The most common type of booster unit used for the MGA is the remote vacuum-powered booster. Unlike systems found in some modern cars that integrate directly with the brake pedal, this unit is installed downstream from the master cylinder. It uses the fluid pressure output from the master cylinder to trigger its power boost function, effectively amplifying the force applied by your foot. Crucially, it uses fluid only from the original master cylinder reservoir, meaning no additional reservoir is required, simplifying the installation slightly.
A significant word of caution regarding installation: certain manufacturers, such as Delphi/Lockheed (as sold by Moss Motors USA), specify a particular orientation for their booster units. For instance, instructions might call for the unit to be situated at an angle slightly nose up (typically 25 to 45 degrees), not level. Furthermore, a specific rotational orientation, often within 60 degrees of vertical and not sideways, may be required. This precise positioning is likely necessary to ensure proper bleeding of the unit, allowing air to be expelled efficiently from the fluid circuit. Failing to adhere to these guidelines could lead to air traps within the system, compromising braking performance. It's worth noting that many images found online might show boosters mounted in what would be an incorrect orientation according to these instructions, so always consult the manufacturer's specific guidance for your chosen unit.
The Double-Edged Sword: Reliability and Potential Failure Modes
While a brake booster offers convenience, it's essential to consider its impact on the overall reliability and service requirements of your MGA. A brake booster is an additional component in the braking system, and as such, it introduces an additional possible mode of failure. This increased complexity can potentially reduce the car's overall reliability while simultaneously increasing future service needs.
There are a few distinct ways a booster unit can fail:
- Diaphragm Failure: If the internal rubber diaphragm cracks or splits, the unit can lose its boost capability. This typically means the brakes will revert to manual operation, requiring significantly more pedal force. While you won't lose braking, the sudden change in feel can be startling.
- Vacuum Leak: A split diaphragm also creates a vacuum leak into the intake manifold. This can cause the intake fuel mixture to go lean, particularly at low engine speeds. Symptoms might include an increased idle speed, or conversely, the weaker fuel mixture could cause the engine to stumble or stall from idle. More seriously, prolonged running with a vacuum leak and an abnormally weak fuel mixture at moderate road speeds could lead to hot running and potentially burned valves in the engine.
- Remote Master Cylinder Seal Leak: Should the remote master cylinder within the booster unit develop a leak in the rubber seal between the cylinder and the vacuum chamber, brake fluid can be sucked out of the system. This fluid would then be passed into the intake manifold and burned. The insidious nature of this failure is that there may be no immediate clue it's happening until the fluid level in the reservoir drops low enough to start sucking air. At this critical point, you could suddenly lose your brakes entirely. For this reason, some owners might consider installing a fluid level warning device for the master cylinder as an additional safeguard.
Considering Dual Line Braking Systems
For those contemplating a conversion to a dual-line braking system for enhanced safety (where the front and rear brakes operate on separate hydraulic circuits), it's important to note that this setup would typically require two remote brake boosters, as was implemented on the MGC. An alternative approach involves using a different type of booster unit that is actuated directly from the brake pedal, similar to those found in post-1974 MGBs. However, such a modification is substantially more involved, often requiring a separate master cylinder for the hydraulic clutch. Furthermore, the direct-acting booster with its attached master cylinder may not physically fit into the same space as the standard dual carburettor setup on an MGA, presenting significant packaging challenges.
Ultimately, while a dual-line braking system can be considered a significant safety feature, providing a failsafe in case of a single circuit failure, a power brake booster is simply a luxury option. Many purists argue that such added complexity and additional weight do not belong on a small, light sports car like the MGA, preferring the direct, unassisted feel of the original setup.
| Pros | Cons |
|---|---|
| Reduced pedal effort | Does not improve stopping power |
| More comfortable driving (especially in traffic) | Reduces tactile feedback (spongy pedal feel) |
| Adds complexity to the braking system | |
| Introduces new potential failure modes | |
| Risk of vacuum leaks affecting engine performance | |
| Risk of brake fluid being consumed by engine in case of seal failure | |
| Adds weight to the vehicle |
Braking Systems for the MGA MkII and Beyond
The MGA MkII, like its predecessors, typically came equipped with drum brakes on all four wheels as standard. While these were effective for their time, the evolution of automotive technology quickly favoured disc brakes for their superior performance characteristics. The introduction of disc brakes on the MGA 1600 models, particularly at the front, marked a significant improvement in the braking capabilities of the MGA lineage.
For owners of earlier MGA models, including the 1500 cc and MkII, converting to front disc brakes has become a popular and highly recommended upgrade. This is where the aforementioned 1500 cc front disc brake plate becomes particularly relevant, allowing these earlier cars to benefit from the performance of the 1600 MGA's disc brake setup without the more invasive modifications often associated with such conversions. While the MkII's original drum brakes are perfectly functional when well-maintained, the upgrade to discs offers a noticeable improvement in safety and driving confidence, especially in modern traffic conditions where sudden stops are more common and sustained braking demands are higher. The choice to upgrade often comes down to a balance between preserving originality and enhancing contemporary usability and safety.
Frequently Asked Questions (FAQs)
Q: Is a disc brake conversion difficult for an MGA 1500?
A: Without the specific 1500 cc front disc brake plate, a conversion can be quite involved, often requiring adaptations to suspension components and adjustments to camber and tracking. However, with the use of the specialised plate, which allows the direct mating of MGB callipers with 1600 MGA discs and hubs, the process is significantly simplified, making it a more accessible upgrade for the 1500 cc model.
Q: Will a brake booster make my MGA stop faster?
A: No, a brake booster does not improve the stopping ability or reduce the stopping distance of your MGA. Its sole purpose is to reduce the pedal force required to actuate the brakes, making the pedal feel lighter and easier to press. The MGA's brakes are inherently capable of locking the wheels when in good condition, whether with or without a booster.
Q: What are the main benefits of converting to disc brakes on an MGA?
A: The primary benefits include superior stopping power, particularly in repeated or heavy braking situations (less brake fade), better performance in wet conditions, and generally simpler maintenance (easier pad replacement compared to drum shoe replacement and adjustment). They also provide a more consistent and firm pedal feel.
Q: How do I know if my brake booster is failing?
A: Common signs of a failing brake booster include a sudden increase in the required pedal force (feeling like the power assist has gone), an audible hiss or whoosh from the booster area (indicating a vacuum leak), or a noticeable change in engine idle speed or performance (due to a vacuum leak affecting the fuel mixture). In severe cases, a drop in brake fluid level without an obvious external leak could indicate fluid being drawn into the engine.
Q: Is it safe to drive without a brake booster if it fails?
A: If a remote vacuum booster fails, the brakes will typically revert to manual operation. This means you will still have braking capability, but it will require significantly more pedal effort. While technically safe to drive, the increased effort can be surprising and potentially dangerous in an emergency. It is advisable to have a failing booster inspected and repaired or replaced promptly.
Conclusion
The world of MGA maintenance and upgrades offers a fascinating journey for any classic car enthusiast. The introduction of the 1500 cc front disc brake plate has undeniably made performance and safety enhancements more accessible for earlier models, allowing owners to enjoy the benefits of modern braking technology without sacrificing the vehicle's original character. Similarly, the decision regarding a brake booster boils down to personal preference for pedal feel versus the added complexity and potential reliability concerns. Whether aiming for authentic originality or a subtle modern touch, understanding these key components empowers MGA owners to make informed choices, ensuring their beloved roadster remains a joy to drive on any road.
If you want to read more articles similar to MGA Braking: Disc Conversions & Boosters Explained, you can visit the Brakes category.