Pinpoint Test F: Clutch-Related Vibrations

Manual Transmission and Clutch

Pinpoint Tests

Pinpoint Test F: 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 belts
- Release bearing
- Flywheel

PINPOINT TEST F: CLUTCH-RELATED VIBRATIONS

-------------------------------------------------
F1 CHECK FOR ENGINE COMPONENT GROUNDING

- With the vehicle in NEUTRAL, position it on hoist. Refer to Jacking and Lifting Service and Repair.
- Check the engine and transmission mounts for grounding.
- Check for exhaust manifolds or other engine components grounding on the body or frame.
- Is there evidence of grounding on the body or frame?

Yes
REPAIR components as necessary. Refer to the appropriate information for the procedure. TEST the system for normal operation.

No
GO to F2.

-------------------------------------------------
F2 CHECK FOR ACCESSORY DRIVE VIBRATIONS

- Remove the accessory drive belt. Refer to Accessory Drive [1][2]Diagrams.
- Start the engine.
- Does the vibration stop when the accessory drive belt is removed from the engine?

Yes
REFER to Accessory Drive Testing and Inspection to diagnose the accessory drive belt components.

No
STOP the engine and REINSTALL the drive belt. GO to F3.

-------------------------------------------------
F3 CHECK FOR RELEASE BEARING NOISE

- Start the engine.
- Depress and hold the clutch pedal.
- Is a whirring, grating or grinding noise present only when the pedal is pushed?

Yes
INSTALL a new clutch release hub and bearing.

No
GO to F4.

-------------------------------------------------
F4 INSPECT THE FLYWHEEL

- Ignition OFF.
- Remove the transmission. Refer to Manual Transaxle/Transmission Manual Transmission.
- Inspect the flywheel for wear or damage.
- Is the flywheel OK?

Yes
VERIFY the customer concern. GO to Symptom Chart - Manual Transmission Operation Symptom Chart - Transmission Operation or GO to Symptom Chart - NVH Symptom Chart - NVH if necessary.

No
TIGHTEN or INSTALL a new flywheel. Refer to the appropriate information for the procedure.

-------------------------------------------------