Vibration Issue

Vibration in a 924S can come from several different areas including the engine, drivetrain, suspension, or the wheels and tires.

Step 1: Pinpoint the Type of Vibration

  • At idle, stationary → Likely engine mounts, balance shaft timing, or misfire.

  • Under acceleration → Driveline, clutch, or engine imbalance.

  • At a steady speed → Wheels, tires, driveshaft, or transaxle.

  • During braking → Warped rotors or suspension bushings.

Step 2: Common Causes & Fixes for the 924S

  1. Wheels & Tires

    • Check for flat spots, bent rims, or uneven wear.

    • Get them road-force balanced (standard balancing isn’t always enough).

    • Make sure tires are not old and hardened.

  2. Engine Balance Shafts

    • The 924S (like the 944) has counter-rotating balance shafts. If the timing belt for the balance shafts is off by even one tooth, it will cause a persistent vibration.

    • Solution: Verify correct belt alignment and tension.

  3. Motor & Transaxle Mounts

    • Worn rubber mounts allow the engine or transaxle to shake the body.

    • Replace with OEM or performance mounts (many owners go for 944-spec mounts).

  4. Driveshaft (Torque Tube) Bearings

    • The long torque tube shaft can develop worn bearings → vibration at speed.

    • If bad, you’ll feel it in the seat more than the steering wheel.

    • Solution: Rebuild or replace torque tube bearings.

  5. Clutch & Flywheel

    • If the clutch disc or pressure plate is unbalanced, it will vibrate under load.

    • A failing rubber-centered clutch (stock on the 924S) can cause violent driveline shudder.

    • Solution: Upgrade to spring-centered clutch when replacing.

  6. Suspension Bushings

    • Control arms, trailing arms, and sway bar bushings wear out and cause shimmy.

    • Replace with new rubber or polyurethane.

  7. Brakes

    • Warped rotors cause vibration when braking.

    • Check rotor runout and pad wear.

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Step 3: Diagnostic Checklist

 Does it shake at idle in neutral? → Check engine mounts, timing, balance shafts.

 Does it only shake at certain speeds (e.g., 50–70 mph)? → Wheels, tires, torque tube.

 Does it worsen when braking? → Rotors or suspension bushings.

 Does it feel through the seat, not steering wheel? → Driveshaft/torque tube/transaxle.

 Does it feel through the steering wheel? → Front wheels, suspension, alignment.