LOSS OF DRIVE / 125 TRANS BURNED FORWARD CLUTCH

When determining the cause of a burned forward clutch in any 1982 THM 125 or 125C transmission, be certain to check the forward clutch housing for cracks as follows:

Air check the assembled clutch housing using approximately 30 psi, and watch for leaks at the areas shown in Figure 1. If a leak is found, replace the forward clutch housing.

If no cracks are evident, check the following items:

(1) Check for missing or damaged seal rings on the input shaft.

(2) Check for a missing or damaged input shaft thrust washer.

(3) If the forward clutch contains a ball capsule, check it for damage or improper sealing.

(4) Check the backing plate for correct installation.

(5) Disassemble the clutch and air check the input shaft feed passage for restrictions or blockage.

(6) Check the piston lip seals for cuts or damage.

(7) Check all the surfaces which the seals contact for nicks or scratches, for example, piston pocket and driven sprocket support sleeve.

If no cause if found, refer to service manual for further diagnosis.

After finding the cause of a burned clutch, reassemble the clutch replacing any worn or damaged parts. Then air check the clutch again and check for leaks.

Properly diagnosing the cause of a burned clutch will prevent a later recurrence of the same condition.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.