Pinpoint Test D: Clutch Drag, Also Hard to Shift
Manual Transmission and Clutch
Pinpoint Test D: Clutch Drag, Also Hard to Shift
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:
- Internal operation
- Clutch pedal reserve
- Clutch slave cylinder travel
- Clutch disc
- Clutch pressure plate
- Clutch pedal free play
PINPOINT TEST D : CLUTCH DRAG, ALSO HARD TO SHIFT
D1 CHECK FLUID LEVEL
- Ignition OFF.
- Remove the reservoir cap.
- Inspect the fluid level in the brake and clutch reservoir.
Is the fluid level at or above the step mark?
Yes
INSTALL the reservoir cap. GO to D2.
No
ADD brake fluid. GO to D2 and CHECK for leaks. TEST the system for normal operation.
D2 INSPECT THE CLUTCH HYDRAULIC SYSTEM FOR LEAKAGE
- Inspect the clutch master cylinder and the hydraulic tubes for leakage.
- Inspect the reservoir and reservoir tube for leakage.
- Inspect the clutch slave cylinder and the hydraulic tube connection for leakage.
Are there any signs of leakage?
Yes
INSTALL new components as necessary. TEST the system for normal operation.
No
GO to D3.
D3 CHECK INTERNAL OPERATION
- Remove the reservoir cap.
- Have an assistant slowly apply and release the clutch pedal.
- On the down stroke, the fluid level should not increase by more than 1 mm (0.039 in).
Does the fluid level increase more than 1 mm (0.039 in)?
Yes
INSTALL a new clutch master cylinder assembly.
No
GO to D4.
D4 CHECK THE CLUTCH PEDAL RESERVE
NOTE: The clutch reserve is the distance between the clutch pedal when fully applied and the position when the vehicle starts to move forward.
- Park the vehicle on a level surface.
- Check for obstructions behind the clutch pedal. Check the carpet for correct installation. Remove the floor mat.
- Attach a cable tie to the lower clutch pedal.
- Attach a tape measure to the cable tie.
- Apply the clutch fully and start the vehicle.
- Shift the transmission into 1st gear.
- Use the seam on the steering wheel as a reference point.
- While observing the tape measure, slowly engage the clutch, noting when the vehicle starts to move forward or a noticeable engine rpm decrease occurs (noted on tachometer).
Is the clutch pedal reserve greater than or equal to 25 mm (0.984 in)?
Yes
The clutch hydraulic system is OK. TEST the system for normal operation.
No
GO to D5.
D5 CHECK THE CLUTCH PEDAL FREE PLAY
NOTE: The clutch pedal free play is the distance between the clutch pedal when fully released and the position when slight resistance is felt on downward motion.
- Engine OFF.
- Attach a tape measure to the cable tie.
- While observing the tape measure, slowly push downward on the clutch pedal until a slight resistance is felt.
Is the clutch pedal free play less than 13 mm (0.511 in)?
Yes
The clutch hydraulic system is OK. TEST the system for normal operation.
No
GO to D6.
D6 CHECK THE CLUTCH PRESSURE PLATE
- Remove the clutch pressure plate.
- Inspect the clutch pressure plate for wear or runout. Refer to Clutch Pressure Plate Check .
Are there any signs of excessive wear or runout to the clutch pressure plate?
Yes
INSTALL a new clutch pressure plate.
No
GO to D7.
D7 INSPECT THE CLUTCH DISC
- Carry out the clutch disc inspection procedure.
Is the clutch disc OK?
Yes
GO to D8.
No
INSTALL a new clutch disc. TEST the system for normal operation.
D8 INSPECT THE TRANSMISSION
- Remove the transmission.
- Disassemble the transmission.
- Carry out the following:
- Inspect all the shift rails for excessive scuffing or wear.
- Check the interlock pins on the shift rail.
- Make sure the interlock bolts are tightened to specifications.
- Inspect the shift pads for wear or cracking.
- Inspect the shift forks for wear or damage.
- Check the synchronizer rings of the affected gear for wear or damage.
- Check the synchronizer hubs of the affected gear for wear or damage.
- Inspect the clutching teeth of the affected gear.
Are there any internal components worn or damaged?
Yes
INSTALL new components or REPAIR as necessary. TEST the system for normal operation.
No
ASSEMBLE and INSTALL the transmission. TEST the system for normal operation.