Tools Required

1. Inspect the underdrive one-way clutch before disassembly by placing the underdrive one-way clutch onto the rear of the underdrive clutch drum, holding the underdrive clutch drum stationary and rotating the underdrive one-way clutch.
2. The underdrive one-way clutch should turn freely in a counterclockwise direction (2) and should not turn in a clockwise direction (3). If the underdrive one-way clutch is installed correctly on the underdrive clutch drum and the underdrive one-way clutch can be turned clockwise, replace the underdrive one-way clutch.



3. Use a J 7872 to measure the underdrive clutch (1) piston stroke before disassembly.

•	Temporarily install the old underdrive clutch drum support seal rings on the underdrive clutch drum support in the transaxle case.

•	Place the underdrive clutch drum on the underdrive clutch drum support in the transaxle case and the J 7872 plunger on the underdrive clutch piston.




4. Apply 392-785 kPa (57-114 psi) of compressed air into the underdrive clutch apply passage (1) in the transaxle case and observe the J 7872

•	The standard underdrive clutch piston stroke should fall within 1.500-1.900 mm (0.0590-0.0748 in).

•	If the underdrive clutch piston stroke is greater or less than specified, inspect all underdrive clutch components for excessive wear.





Caution: Wear safety glasses in order to avoid eye damage.

Notice: The underdrive one-way clutch should be disassembled for inspection purposes only. If excessive wear or damage is found in any component of the underdrive one-way clutch upon inspection, replace the underdrive one-way clutch as an assembly.

5. Remove the rear thrust plate (2) from the underdrive one-way clutch outer race (1).



6. Remove the underdrive one-way clutch retainers (2, 4) and the sprag assembly (3) from the underdrive one-way clutch outer race.



7. Remove the underdrive clutch snap ring (2) from the underdrive clutch drum (1).



8. Remove the following components from the underdrive clutch drum (1):

•	The underdrive clutch flange

•	The 4  discs

•	The 4  plates




9. Use a J 23327 with a J 37279 to remove the underdrive clutch piston return spring snap ring (1) from the underdrive piston return spring (2).



10. Remove the following components from the underdrive clutch piston:

•	The underdrive clutch piston return spring (1)

•	The underdrive clutch piston return spring plate (2)





Important: When using compressed air to remove components, air pressure should not exceed 98 kPa (14 psi).

11. Remove the underdrive clutch piston from the underdrive clutch drum by placing the underdrive clutch drum on the underdrive clutch drum support in the transaxle case and applying low pressure compressed air into the underdrive clutch apply passage (1) in the transaxle case (2).
12. Remove the underdrive clutch drum from the underdrive clutch drum support in the transaxle case.
13. Inspect the following components for excessive wear or damage and replace the underdrive one-way clutch assembly as necessary:

•	The underdrive one-way clutch sprag assembly

•	The underdrive one-way clutch outer race

14. Inspect the underdrive clutch discs for excessive wear or damage and replace as necessary.
15. Inspect the underdrive clutch piston for cracks or porosity and replace as necessary.
16. Inspect the underdrive clutch piston check ball operation by applying compressed air into the working and release sides of the underdrive clutch piston.
17. There must be no air leakage on the working side and air must pass freely through the release side. If these conditions do not exist, replace the underdrive clutch piston.
18. Inspect the underdrive clutch piston return spring for distortion or weakness and replace as necessary.



19. Use a J 26900-6 to measure the inside diameter of the front and rear underdrive clutch flange (3) bushings.

•	The standard underdrive clutch flange bushing diameter should measure within the following parameters:

-	Front (1) 46.500-46.525 mm (1.8307-1.8316 in).

-	Rear (2) 55.000-55.030 mm (2.1653-2.1665 in).

•	The maximum inside diameter of the underdrive clutch bushing should measure within the following parameters:

-	Front 46.570 mm (1.8334 in)

-	Rear 55.080 mm (2.1685 in)

-	If the inside diameter of the underdrive clutch bushings are greater than specified, replace the underdrive clutch drum.

Caution: Wear safety glasses in order to avoid eye damage.

Notice: When installing new clutch discs in the 1st-reverse brake, forward clutch or direct clutch assemblies, the new clutch discs MUST be soaked in Dexron® - III automatic transmission fluid GM P/N 12341643, or equivalent, two hours prior to installation. This causes the clutch material on the discs to permeate with fluid which will aid in ease of assembly and prevent clutch overheating on first time engagement.

Important: When using compressed air to remove components, air pressure should not exceed 98 kPa (14 psi).

1. Install the two underdrive clutch piston seals (1) onto the underdrive clutch piston (2).
2. Apply J 36850 to the new underdrive clutch piston seals.



3. Install the underdrive clutch piston (1) into the underdrive clutch drum (2).
4. Install the underdrive clutch piston return spring and the underdrive clutch piston return spring into the underdrive clutch piston.



5. Use a J 23327 with a J 37279 to install the underdrive clutch piston return spring snap ring onto the underdrive piston return spring (2).



6. Install the 4  discs, 4 plates and underdrive clutch flange into the underdrive clutch drum (1) in the following order:

•

1 plate

•

1 disc

•

1 plate

•

1 disc

•

1 plate

•

1 disc

•

1  plate

•

1 disc

Important: The underdrive clutch flange must be installed with the flat side facing down and the stepped portion facing upwards.

7. Install the flange.
8. Install the underdrive clutch snap ring into the underdrive clutch drum.



9. Install the underdrive one-way clutch sprag assembly (3) and retainers (2, 4) into the underdrive one-way clutch outer race (5).



10. Install the rear thrust plate (2) onto the underdrive one-way clutch outer race (1).



11. Use a J 7872 to measure the underdrive clutch piston stroke after assembly.
12. Place the underdrive clutch drum (1) on the underdrive clutch drum support in the transaxle case and the J 7872 plunger on the underdrive clutch piston.



13. Apply 392 to 785 kPa (57 to 114 psi) of compressed air into the underdrive clutch apply passage (1) in the transaxle case and observe the J 7872 .

•	The standard underdrive clutch piston stroke should fall within 1.500 to 1.900 mm (0.0590 to 0.0748 in).

•	If the underdrive clutch piston stroke does not fall within specification, select one of the two following underdrive clutch flange sizes to bring the underdrive clutch piston stroke within specification:

-	2.040 mm (0.0803 in)

-	2.400 mm (0.0945 in)

•	Remove the old underdrive clutch drum support seal rings from the underdrive clutch drum support.




14. Inspect the underdrive one-way clutch after assembly by placing the underdrive one-way clutch onto the rear of the underdrive clutch drum, holding the underdrive clutch drum stationary and rotating the underdrive one-way clutch.

•	The underdrive one-way clutch (1) should turn freely in a counterclockwise direction (2) and should not turn in a clockwise direction (3).

•	If the underdrive one-way clutch is installed correctly on the underdrive clutch drum and the underdrive one-way clutch can be turned clockwise, replace the underdrive one-way clutch.