Clutch Slip (Replace Clutch Actuator Cylinder Spacer)

Some operators may comment that the clutch is slipping and burned. This may reoccur at short intervals.

The condition may be caused from the hydraulic clutch actuator cylinder not completely retracting. This incomplete release may result in a clutch that slips most of the time as the vehicle is driven. A premature failure of the clutch may also occur.

These vehicles use a hydraulic actuation system. There is normally no free play in the clutch pedal. Because of this, the operator may not detect an incomplete clutch release.

Clutch Pedal Return Stop

In order to achieve maximum clutch pedal release, slightly adjust the clutch pedal bracket at the bump stop. This will create clutch free play. Adjust the bracket until you can feel a slight free play between the clutch master cylinder and the push rod in the cab.

New Spacer Plate

Repositioning the clutch actuator cylinder closer to the transmission may improve the operation of the actuator cylinder. A revised clutch actuator cylinder spacer plate has been developed that accommodates this repositioning.

The legs of the spacer plate have been shortened by 7 mm (0.28 in) and the spacers have also been revised to ensure proper clearance around the transmission front bearing retainer.

Install a new clutch actuator cylinder spacer plate on affected vehicles. Refer to Section 7C-7 of the 1997 MD T-Series Service Manual. Use the part numbers listed below.

Flywheel Condition

Verify the condition of the flywheel. The flywheel face must be flat. If the flywheel face exhibits any of the following conditions, you can machine the flywheel up to 3 mm (0.12 in).

A new clutch installed against a warped flywheel may cause the clutch to prematurely fail.

Clutch Actuator

Use the following steps in order to inspect the actuator Cylinder:

1. Disassemble the clutch actuator.
2. Inspect the actuator for corrosion or foreign debris in the bore. Collapse the piston using hand pressure while an assistant removes the snap ring.
3. Thoroughly clean and remove any corrosion or debris from the back side of the piston and the cylinder bore.

Important: The clutch actuator cylinder must operate freely and collapse completely when the driver's foot is removed from the clutch pedal. If the piston does not retract and sticks out, the clutch will drag.

4. If there is any doubt as to the integrity of the clutch actuator cylinder, replace the cylinder.

Clutch Drag

When the above repairs have been completed, verify that the clutch is not dragging with the clutch pedal down.

1. Raise the vehicle. Install support stands under the rear axle.
2. Start the engine.
3. Place the transmission in first gear.

Important: 

•	The rear tires should not spin with any force with the clutch pedal down. There may be a tendency for tire rotation even with the clutch pedal down. With the aid of an assistant, you should be able to stop the rotation of the tire using a broom handle.

•	If the tires spin with significant force , then the clutch is dragging. investigate and resolve other potential causes for this condition. The clutch actuator cylinder may not be fully retracting. Replace the clutch actuator cylinder if required.

4. Depress the clutch pedal.

Parts are currently available from GMSPO.