SMU - Driven Sprocket Support Revised Art/Procedure for Hydra-Matic 4T80-T Auto

This bulletin is being issued to revise the Service Manual art and procedure for the disassembly and assembly of the Driven Sprocket Support. Attached are the updated pages for the 1996-2000 Unit Repair Service Manual Sections. Replace these pages in your Service Manual. The updated Service Manual information shows the Driven Sprocket Support art and procedure without the third clutch exhaust valve cup plug (426). This third clutch exhaust valve cup plug (426) was removed from production April 5, 1996 (Julian date 095). The sub-assembly parts for the Driven Sprocket Support Assemblies produced after the above Julian date are not interchangeable with the sub-assembly components for the Driven Sprocket Support Assemblies produced prior to the above Julian date. When the third clutch exhaust valve cup plug (426) was removed from production, the length of the third clutch exhaust valve spring (425) was increased as well. However, the Driven Sprocket Support Assembly - Complete is interchangeable.

Tools Required

J 39694 Second Clutch Spring Compressor

1. Use the J 39694 second clutch spring compressor to compress the spring and remove the snap ring (429). Then remove the spring compressor.



2. Remove the return spring and retainer assembly (428), and remove the piston assembly (430).



3. Remove the following parts:

•	The two sealing rings (423)

•	The two oil rings (422)

•	The scavenge tube seal (53)




4. Remove the following parts:

•	The third clutch exhaust valve spring retaining pin (424)

•	The third clutch exhaust valve spring (425)

•	The third clutch exhaust valve (427)

5. Remove the oil transfer sleeve (419).

Tools Required

J 39694 Spring Compressor

1. Inspect the driven sprocket support (418) for the following:

•	Hub nicks, burrs, or damage

•	Plugged feed holes

•	Worn or damaged splines

•	Bushings for nicks, scratches, or wear

•	The checkball for movement

•	The seal ring grooves for damage




2. Inspect the following parts for damage:

•	The third clutch exhaust valve (427)

•	The exhaust valve spring (425)

•	The oil transfer sleeve (419)




3. Inspect the two sealing rings (423) and the two oil rings (422). Replace any damaged rings.
4. Inspect the scavenge tube seal (53). If the seal is damaged, replace the seal.



5. Inspect the second clutch piston and seal assembly (430). Inspect the second clutch spring and retainer assembly (428) for damage. Replace any damaged part.

Notice: Do not roll the seals when installing the second clutch piston assembly (430), or damage may occur.

6. Install the second clutch piston assembly (430). Twist and push the piston simultaneously. Use a light coating of J 36850 or equivalent.



7. Use the J 39694 to compress the spring and retainer assembly (428).
8. Install the snap ring (429).



9. Install the following parts:

•	The third clutch exhaust valve (427)

•	The third clutch exhaust valve spring (425)

•	The spring pin (424)




10. Air check the second clutch piston by applying air through the driven sprocket support (418).



11. Install the driven sprocket support (418-427) over the input shaft. When seated, the support will be flush with the case line surface.