Pinpoint Test E: Clutch Related Vibrations

Manual Transaxle and Clutch






Pinpoint Tests

Pinpoint Test E: Clutch Related Vibrations

Normal Operation

The clutch is designed to transfer the power from the engine to the transmission, which may be either stationary (starting) or rotating at a different speed (upshifting or downshifting). The clutch is functioning correctly when both the engine and transmission are rotating at the same speed with the clutch engaged. Clutch pedal movement is transmitted by fluid pressure, which actuates the clutch release hub and bearing. The clutch release hub and bearing pushes on the spring center towards the flywheel. The diaphragm spring pivots at the fulcrum, relieving the load on the clutch pressure plate. Steel spring straps riveted in the clutch pressure plate cover pull the clutch pressure plate from the clutch disc, disengaging the engine torque from the transmission.

This pinpoint test is intended to diagnose the following:
- Engine components
- Accessory drive component
- Release bearing
- Flywheel



PINPOINT TEST E: CLUTCH RELATED VIBRATIONS

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E1 CHECK FOR ENGINE COMPONENT GROUNDING


- Raise and support the vehicle.
- Check the engine mount interlocks for grounding on the body or frame.
- Check the exhaust manifold or other engine component grounding on the body or frame.
- Is there evidence of grounding on body or frame?

Yes
REPAIR or INSTALL new as necessary. TEST the system for normal operation.

No
GO to E2.

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E2 CHECK FOR ACCESSORY DRIVE VIBRATIONS


- Feel accessory vibration at clutch engage/disengage when engine torque changes.
- Disconnect the accessory drive belt and check for vibration.
- Does the vibration stop when the drive belt is removed from the engine?

Yes
REPAIR or INSTALL new accessory drive belt components. REFER to Drive Belts, Mounts, Brackets and Accessories.

No
GO to E3.

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E3 CHECK FOR RELEASE BEARING NOISE


- Start engine.
- Depress and hold clutch pedal.
- Is a whirring, grating or grinding noise present?

Yes
INSTALL a new clutch slave cylinder. REFER to Clutch, M/T. TEST the system for normal operation.

No
GO to E4.

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E4 INSPECT THE FLYWHEEL


- Remove the transaxle. Refer to Manual Transmission/Transaxle.
- Inspect for loose flywheel bolts.
- Carry out flywheel runout check. Refer to Engine.
- Is the flywheel OK?

Yes
DIAGNOSE engine vibration concern. REFER to Engine.

No
TIGHTEN the flywheel bolts or INSTALL a new flywheel. REFER to Clutch, M/T. TEST the system for normal operation.

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