Unravelling Subaru's Clutch Changes Over Years

The clutch is an often-overlooked yet utterly vital component in any manual transmission vehicle, acting as the crucial link between your engine and gearbox. For Subaru owners, understanding the nuances of their vehicle's clutch system is particularly important due to the brand's unique powertrain configurations and the evolution of its clutch designs over the years. From the robust, straightforward setups of yesteryear to the more sophisticated, vibration-dampening technologies of today, Subaru clutches have undergone significant transformations to meet changing driver demands and technological advancements. This guide will delve into the fascinating journey of Subaru's clutch systems, helping you comprehend the variations, identify potential issues, and make informed decisions about your vehicle's maintenance.

Evolution of Subaru Clutches: A Technical Deep Dive

Subaru's commitment to engineering excellence has led to continuous refinement across all its vehicle systems, and the clutch is no exception. Recent years have seen notable shifts in clutch kit designs, primarily driven by technical changes in Subaru engine and gearbox configurations. Popular models such as the Subaru Outback, Liberty, Forester, and Impreza have all been impacted by these evolutions, particularly with the replacement of superseded Dual Mass clutch kits by the more advanced Wide Acting Dampener (WAD) units. These changes are not merely incremental; they reflect a strategic effort to enhance driveability, reduce noise, and manage vibrations more effectively.

Push-Type vs. Pull-Type Clutches: A Fundamental Shift

Historically, Subaru has employed two primary clutch actuation mechanisms: Push-type and Pull-type. Each has distinct characteristics, advantages, and disadvantages that have influenced their application across different Subaru models and generations.

Subaru Push-Type Clutch: Non-Turbo and Turbo Models

Prior to 1999, solid type clutches were the common fitment for Subaru 5-speed models. While robust, advancements in vehicle design aimed at reducing interior cabin noise inadvertently led to increased transmission of vibrations to the vehicle's interior.

The introduction of the Subaru DualMass clutch kit marked a significant step forward in vibration management. This technology works by using independent masses separated by springs, effectively splitting the inertia between the Subaru engine and gearbox. This clever design maintains vibration levels at idle speed, significantly improving cabin comfort. This technology is also critically employed in Subaru Diesel clutches, where precise vibration control is essential for the engine's operation. While improving driveability and reducing noise, the dual mass clutch has also generated considerable discussion among owners and mechanics regarding its operational characteristics and long-term reliability.

In petrol engines, DualMass clutch kits were primarily available with a Push-type clutch for non-turbo models, commonly found in the 1999 Outback, Liberty, and Forester. However, these early iterations often presented problems, leading Subaru to convert vehicles to WAD clutches under warranty repairs. For the past five years, Subaru has largely moved away from DualMass clutches in petrol engines. Interestingly, they have reverted to using DualMass for diesel models, where its noise-reduction properties are highly beneficial. A key advantage of the DualMass clutch is the improved gearbox shift feel due to lower reciprocating clutch plate mass, though it typically comes at a higher replacement cost. Awareness of these specific issues is crucial, particularly for 2.5-litre Liberty, Outback, and Impreza clutch kits.

Subaru Pull-Type Clutch: Performance and Reliability

In contrast to the Push-type, the Pull-type clutch, while more expensive to produce and technically more challenging to fit, is renowned for being a more reliable and robust unit. This inherent durability is precisely why it remains the preferred choice for high-performance models, such as the STi.

The five-speed Pull clutch, used from 1991 to 2000, featured a 230 mm pressure plate paired with a solid flywheel. Following 2000, Subaru transitioned to the semi-flex flywheel for these models. However, after 2006, all turbo five-speed models converted to the Push-type clutch system. This transition, unfortunately, introduced a new set of problems, primarily concerning damage to the front "snouts" of gearbox casings, necessitating costly repairs or even full gearbox replacements in some cases.

The six-speed Pull clutch, found in all Liberty and STi models, utilises a larger 240 mm pressure plate and has consistently maintained a solid flywheel setup. This particular configuration has proven to be exceptionally reliable, with no reported issues to date, underscoring the Pull-type's robustness in demanding applications.

To summarise the distinctions between these clutch types:

Subaru Flywheel Variations: Impact on Performance and Durability

While Subaru flywheels are inherently well-engineered and robust components, evolving driveline variations and customer demands for improved driveability and fuel consumption have prompted the introduction of three distinct Flywheel types. Each offers specific advantages and disadvantages that influence the overall performance and longevity of the clutch system.

Solid Flywheel

Subaru utilised the solidFlywheel from 1991 to 2000, a period during which it established itself as the most reliable clutch setup, particularly popular and robust in Subaru turbo models. Despite its reliability, this setup was known to produce some gearbox noise, often described as "chattering" or what Subaru officially labelled "garaga" noise. This sound is a normal byproduct generated by the third and fourth gear clusters, amplified through the solidFlywheel. Even today, the solidFlywheel remains in use with the Pull-type clutch in STi 6-speed models, a testament to its enduring strength. A significant advantage of this Flywheel type is its machinability, which contributes to its renowned long service life.

Semi-Flex Flywheel

The semi-flex Flywheel was introduced around 2003, initially for non-turbo petrol models to address issues associated with the DualMassFlywheel, and became a standard feature from 2006 onwards. This type was eventually adopted for both turbo and non-turbo petrol engines. While turbo 5-speed models received the DualMassFlywheel in 2002 and have largely retained this setup without significant problems (albeit with minor product number changes), the semi-flex is notorious for developing "chattering" when it becomes worn. Crucially, unlike the solidFlywheel, the semi-flex type is not suitable for machining, meaning it must be replaced when worn.

Dual Mass Flywheel

The DualMassFlywheel made its debut in petrol non-turbo engines from 1999 until 2005. While initially providing excellent driveability, this particular design has, to date, generated the most warranty issues for Subaru, leading to considerable customer dissatisfaction. Most non-turbo engines originally fitted with DualMass flywheels have since been converted to the semi-flex type. A key benefit of the DualMassFlywheel is its ability to reduce Subaru gearbox noise or gear chatter. However, a significant drawback is its propensity to develop clutch noise, such as a Subaru clutch squeak or rattle at idle, typically after around 60,000kms, depending on driving style. Furthermore, the DualMassFlywheel is non-serviceable and must be discarded once worn, adding to replacement costs.

Here's a comparison of Subaru Flywheel types:

The Perils of Inferior Aftermarket Clutches and Flywheels

The popularity of Subaru models and the relatively high cost of genuine Subaru clutch components, particularly in markets like Australia, have unfortunately led to a proliferation of aftermarket copies. While these non-genuine kits are considerably cheaper than the Original Equipment Manufacturer (OEM) product, they are often manufactured from inferior materials. Experience has shown that most cheap aftermarket clutch products have a significantly shorter service life and fail to perform efficiently. When considering a Subaru clutch replacement, it is paramount to opt for genuine Subaru parts or high-quality Japanese aftermarket kits to ensure longevity and proper function.

Common problems encountered with non-genuine clutch kits include:

• Varying degrees of clutch shudder
• Gearshift issues, such as difficulty engaging gears and a general loss of driveability
• Premature thrust bearing failure
• Unwanted Subaru pedal vibration
• Cracks appearing in flywheels
• Poor Subaru clutch pedal feel
• Clutch pedal sticking
• Clutch slipping under load

Identifying Clutch Problems: Signs Your Subaru Needs Attention

Regardless of the specific clutch type fitted to your Subaru, the symptoms of wear will manifest similarly in both early and advanced stages. It is always advisable to address clutch issues at the first sign of wear. Delaying replacement can lead to cascading damage to other drivetrain components, significantly inflating your repair bill. Furthermore, improper Subaru hill assist and Subaru hill hold functions can sometimes be linked to incorrect Subaru clutch kits or software calibrations, particularly in vehicles equipped with an Electronic Parking Brake (EPB). Hesitation, sluggish performance, stalling, and high idle revs in your Subaru can all be indicative of a malfunctioning clutch.

Early Signs of Wear

Early indications of clutch wear can be subtle, making them easy to miss if you're not attuned to your vehicle's behaviour. If you have any doubts, it's always best to have your car thoroughly checked by a specialist. Look out for:

• The clutch taking up very near the end of the pedal travel.
• An apparent loss of power under load, often caused by slight clutch slip.
• Difficulty engaging gears, particularly first and reverse.
• Increased fuel consumption, as the engine works harder to compensate for slipping.
• A general decline in driveability, where the car just doesn't feel as responsive.

Signs of Advanced Wear

Wear progresses much more rapidly in turbo models compared to non-turbo models. In vehicles fitted with a Pull-type clutch, advanced wear stages might lead to problems with damaged or broken gears and excessively worn flywheels. For Push-type turbo clutches, advanced wear frequently results in severe damage to the gearbox casing "snout," often necessitating a full gearbox replacement. This type of damage is unfortunately common in late model turbo Subarus and, to a lesser extent, in non-turbo models with this clutch setup. Addressing issues promptly can save you from these extensive and expensive repairs.

Frequently Asked Questions About Subaru Clutches

How can I know if my clutch needs replacing?

As detailed above, there are several clear indicators that your clutch is nearing the end of its life. Pay attention to how your clutch pedal feels – is it vibrating, loose, spongy, or sticking? Listen for unusual noises like grumbling or squeaking when you press the pedal. If you're struggling to engage gears, or if you can rev the engine but experience poor acceleration or a momentary loss of acceleration due to clutch slipping, these are definitive signs it’s time for a professional inspection and likely a replacement. Early intervention can prevent more significant damage.

How much does a Subaru clutch replacement cost?

The cost to replace a clutch in a Subaru can vary significantly based on the model, the type of clutch kit required (genuine vs. high-quality aftermarket), and labour rates. Generally, the average cost ranges from £400 to £800 or more. For specific models, the Subaru Impreza clutch replacement cost typically falls between £1,000 and £1,200, while the Subaru Forester and Subaru WRX clutch replacement costs are usually within similar ranges, reflecting the complexity and parts required for these vehicles. These figures are estimates and can fluctuate.

How does a Subaru clutch function?

The clutch acts as a vital intermediary, separating your engine from the car’s drivetrain. This separation is crucial for changing gears smoothly or bringing the vehicle to a complete stop while the engine remains running. A clutch assembly comprises three main components: a clutch plate, a pressure plate, and a Flywheel. When your foot is off the pedal, springs within the clutch press these three pieces together, ensuring the transmission and engine are connected and rotate at the same speed. Conversely, pressing the clutch pedal pulls these springs away from the clutch plate, allowing the other two components to spin at different speeds, thereby enabling you to effortlessly change gears. Over time, these components wear out, impairing gear changes and potentially rendering the car undriveable.

How long will a clutch typically last?

The lifespan of a Subaru clutch is highly variable and depends on numerous factors, including your driving style and the type of driving you predominantly do. While clutches are designed to last at least 50,000 miles, this can differ significantly for each car owner. For instance, if your driving mainly involves city traffic with frequent stop-and-go conditions and numerous gear changes, your clutch is likely to wear out faster than if you primarily engage in highway driving. Proper driving habits, such as avoiding riding the clutch or excessive slipping, can significantly extend its life.

How do you adjust the clutch on a Subaru?

For many Subaru models, particularly those with a hydraulic clutch system, the clutch engagement point is self-adjusting, meaning it doesn't typically require manual adjustment for its grab point. However, the clutch pedal free play can often be adjusted. This involves loosening a specific nut and then turning a rod to either lengthen or shorten it, which alters the amount of play in the pedal before the clutch begins to disengage. While this adjustment can fine-tune pedal feel, it does not correct a worn clutch's engagement point; that requires a replacement. If you suspect an issue beyond simple free play, professional diagnosis is recommended.

Conclusion

Understanding the evolution and intricacies of your Subaru's clutch system is key to its longevity and your driving pleasure. From the early solid designs to the advanced WAD units, Subaru has continuously refined its clutch technology to enhance performance, reduce vibrations, and improve driveability. Being aware of the different types, their associated flywheels, and crucially, the warning signs of wear, empowers you to act proactively. Investing in genuine or high-quality aftermarket parts and addressing issues promptly will ensure your Subaru continues to deliver the reliable, engaging driving experience you expect for many years to come.

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