2020 Subaru WRX Clutch Slipping: Diagnosis and Repair Guide

At a Glance

A problematic clutch is one of the most common and impactful drivability issues for manual transmission vehicles. Based on analysis of 152 owner discussions, clutch problems manifest not just as slipping or grabbing, but often through more subtle symptoms like unusual noises and shifting difficulties. The root causes are varied, ranging from simple hydraulic issues to major mechanical failures like a worn clutch disc or damaged flywheel. Successful repair requires methodical diagnosis, as misdiagnosis can lead to unnecessary and expensive component replacement.

Symptoms Reported by Owners

Owners describe a consistent set of symptoms that signal clutch trouble. The most frequently reported issues are:

• Unusual Noises: A loud, constant chirping, squealing, or rattling noise when the clutch pedal is depressed is the single most common symptom, cited in numerous discussions. This noise often disappears when the pedal is released.
• Difficulty Shifting: Owners report grinding gears during shifts, inability to engage gears (especially first and reverse), or a general "notchy" and stiff feel from the gearshift.
• Pedal Feel Abnormalities: This includes a clutch pedal that is spongy, sticks to the floor, vibrates, or has a very different engagement point (either very high or very low).
• Slipping Under Load: The engine RPMs rise without a corresponding increase in vehicle speed, particularly noticeable in higher gears during acceleration or going uphill.
• Burning Smell: A distinct acrid odor emanating from the engine bay, often after repeated slipping or difficulty with gear engagement.

What's Behind It

The analysis of successful fixes points to several primary culprits. It's critical to note that symptoms often overlap, making the root cause non-obvious without proper checks.

1. Clutch Release Bearing (Throw-Out Bearing or TOB) Failure: This is the leading cause of noise (the classic chirp/squeal on pedal press) and is implicated in a majority of discussions. A failing TOB can also cause rattles and, in severe cases, lead to difficulty disengaging the clutch.
2. Hydraulic System Failure: Problems with the clutch master cylinder, slave cylinder, or hydraulic line are a common source of shifting problems and pedal issues (sponginess, sticking). Air in the system or fluid leaks degrade hydraulic pressure.
3. Worn Clutch Disc/Friction Material: The clutch disc itself eventually wears out, leading to slipping under load. This is often the assumed cause, but the data shows it is frequently preceded by symptoms from the TOB or hydraulics.
4. Damaged Pressure Plate or Flywheel: A warped pressure plate or a damaged flywheel (especially a dual-mass flywheel with failed dampers) can cause severe vibration, grabbing, chattering, and gear grind. Hot spots or cracking on the flywheel surface are common.
5. Pilot Bearing Failure: Less common but significant, a seized or failed pilot bearing in the crankshaft can cause a whirring noise and make transmission installation nearly impossible during repair.

Step-by-Step Diagnosis

A systematic approach prevents unnecessary part replacement. Follow these steps in order:

1. Initial Operational Check: With the engine off, pump the clutch pedal. Does it feel consistently firm, or is it spongy and improves with pumping? A spongy pedal that firms up points directly to a hydraulic issue. Next, with the engine running and the vehicle stationary, listen for the characteristic squeal/chirp when slowly depressing the pedal. This strongly indicates a failing TOB.
2. Test for Slipping: In a safe, open area, drive in a high gear (3rd or 4th) at a low speed (e.g., 30 mph). Firmly press the accelerator. If the engine RPMs jump but the car doesn't accelerate proportionally, the clutch disc is slipping and worn.
3. Hydraulic Inspection: Check the fluid reservoir for the clutch (often shared with the brake fluid). Is it low? Look for leaks along the firewall near the pedal (master cylinder), on the transmission bellhousing (slave cylinder), and along the hydraulic line. Check inside the car near the top of the clutch pedal for fluid drips.
4. Mechanical Linkage Check (if applicable): For vehicles with a cable-operated clutch, inspect the cable for fraying, stretching, or binding. For rod linkages, check for worn bushings and pivot points.
5. Final Verification: If the problem points to an internal component (TOB, clutch disc, pressure plate, flywheel), the only definitive diagnosis is visual inspection after removing the transmission. Before this major labor step, exhaust all external checks.

How to Fix It

Solutions should be attempted in order of cost and complexity, based on the diagnostic results.

1. Bleed the Hydraulic System (Cheapest First Step): If the pedal is spongy or shifting is difficult, bleeding the clutch hydraulic system is the mandatory first step. Use the correct DOT-rated fluid. This simple procedure resolved shifting issues in many cases where air had entered the system. Cost: <$20 (DIY).
2. Replace Hydraulic Components: If bleeding provides only temporary relief or a leak is found, replace the failing component. The slave cylinder is a common failure point. Consider replacing both the master and slave cylinders as a set, as one often follows the other in failing. Success Rate: High for resolving pedal and disengagement issues.
3. Replace the Clutch Release Bearing (TOB): For the predominant squealing/chirping noise, the TOB is almost always the culprit. Critical Note: Replacing the TOB requires transmission removal. Given the labor cost, the overwhelming consensus from all discussions is to replace the entire clutch kit (disc, pressure plate, TOB) and resurface or replace the flywheel while everything is apart. Replacing just the TOB is a false economy.
4. Complete Clutch Kit & Flywheel Service (The Definitive Repair): This is the solution for slipping, severe noise, vibration, or if the transmission is already out. Always install a new clutch kit (disc, pressure plate, TOB, and often a pilot bearing). Have the flywheel professionally resurfaced (for solid flywheels) or replace it entirely (mandatory for dual-mass flywheels, which cannot be resurfaced). This addresses the root cause in nearly 100% of internal clutch failures.

Price Breakdown

Costs vary widely by vehicle, but the following ranges are representative based on part and labor estimates from owner reports.

• DIY (Parts Only):
  • Clutch Kit (Disc, Pressure Plate, TOB): $150 - $400
  • Flywheel (New, if required): $200 - $600 (Dual-mass units are at the high end)
  • Master/Slave Cylinder Set: $50 - $150
  • Total DIY Parts Range: $200 - $1,150
• Professional Shop (Parts & Labor):
  • Hydraulic Component(s) Replacement: $300 - $600
  • Complete Clutch Job (Kit + Flywheel Service): $1,200 - $2,500+
  • Labor is the major cost driver (typically 5-8 hours), and prices are significantly higher for all-wheel-drive vehicles or those with difficult transmission access.

Avoiding This Problem

Prolonging clutch life is primarily about driving technique and addressing small issues promptly.

• Don't "Ride the Clutch": Avoid resting your foot on the clutch pedal while driving. Even slight pressure can cause the TOB to engage and begin wearing prematurely.
• Fully Disengage for Shifts: Ensure the clutch pedal is fully depressed to the floor before shifting to minimize gear grind and synchro wear.
• Address Noises Immediately: The moment you hear the tell-tale TOB squeal, start planning for repair. Continuing to drive can lead to catastrophic bearing failure, which can damage the pressure plate fingers or the transmission input shaft sleeve.
• Maintain the Hydraulic System: Use the correct fluid and change it per the manufacturer's schedule. Treat a spongy pedal or minor fluid leak as an urgent repair to prevent being stranded.
• Consider the Full Job: If any internal repair is needed, budget for the complete clutch kit and flywheel service. Skipping the flywheel work or reusing the old pressure plate is the most common reason for a premature repeat failure.

Source Summary: This analysis is based on 152 owner discussions from Reddit and automotive forums.