No Movement When Transmission is Shifted to Drive or Third - Normal Operation When Shifted to Second, First or Reverse (Replace Forward Sprag Assembly) (08-07-30-027)

Publication date: 2008-06-04
Reference number: 08-07-30-027

No Movement When Transmission is Shifted to Drive or Third - Normal Operation When Shifted to Second, First or Reverse (Replace Forward Sprag Assembly)

TECHNICAL SERVICE BULLETIN

Reference Number(s): 08-07-30-027, Date of Issue: June 04, 2008

Affected Model(s):

1982-2005 GM Passenger Cars and Light Duty Trucks; 2006-2007 Buick Rainier; 2006 Cadillac Escalade, Escalade ESV, Escalade EXT; 2006 Chevrolet SSR; 2006-2008 Chevrolet Avalanche, Colorado, Express, Silverado Classic, Silverado, Suburban, Tahoe, TrailBlazer; 2006 GMC Yukon Denali, Yukon Denali XL; 2006-2008 GMC Canyon, Envoy, Savana, Sierra Classic, Sierra, Yukon, Yukon XL; 2006 Pontiac GTO; 2006-2007 HUMMER H2; 2006-2008 HUMMER H3; 2006-2008 Saab 9-7X; with 4L60, 4L60E, 4L65E or 4L70E Automatic Transmission (RPOs MD8, M30, M32, M33 or M70)

Condition

Some customers may comment that the vehicle has no movement when the transmission is shifted to DRIVE or THIRD position, but there is normal operation when it is shifted to SECOND, FIRST or REVERSE position.

Cause

This condition may be caused by a damaged forward sprag assembly (642).

Correction

When inspecting the sprag, it is important to test the sprag for proper operation by holding the outer race (644) with one hand while rotating the input sun gear (640) with the other hand. The sun gear should rotate only in the counterclockwise direction with the input sun gear facing upward. If the sprag rotates in both directions or will not rotate in either direction, the sprag elements should be inspected by removing one of the sprag assembly retaining rings (643). Refer to SI Unit Repair section for forward clutch sprag disassembly procedures.

If the sprag is found to be damaged, make repairs to the transmission as necessary. A new forward roller clutch sprag assembly is now available from GMSPO.

Fig 1: View Of Pressure Control Solenoid & Components

Courtesy of GENERAL MOTORS CORP.

If clutch debris is found, it is also very important to inspect the Pressure Control (PC) solenoid valve (377) fluid screens. Clean or replace the PC solenoid (377) as necessary. It is also important to flush and flow check the transmission oil cooler using J45096. Refer to SI Automatic Transmission Oil Cooler Flushing and Flow Test for the procedure.

Fig 2: View Of Sprag Assembly Components

Courtesy of GENERAL MOTORS CORP.

Callouts For Previous Graphic

Callout	Component Name
1	The notches above each sprag must point up as shown when assembled into the outer race.
637	Bearing Assembly, Input Sun Gear
638	Snap Ring, Overrun Clutch Hub Retaining
639	Hub, Overrun Clutch
640	Wear Plate, Sprag Assembly
641	Retainer and Race Assembly, Sprag
642	Forward Sprag Assembly
643	Retainer Rings, Sprag Assembly
644	Outer Race, Forward Clutch
660	Washer, Thrust (Input Carrier to Race)

The following information applies when this sprag is used in 1982-86 transmissions.

The new design sprag can be used on models 1982 through 1986, by replacing the entire assembly (637 - 644). Individual components are NOT interchangeable.

IMPORTANT: The wear plate (640) and input thrust washer (660) are not required with the new sprag. Use of the thrust washer and wear plate with the new sprag assembly will cause a misbuild (correct end play cannot be obtained).

Parts Information

Part Number	Description
24241477	Sprag, Forward Clutch

Warranty Information

For vehicles repaired under warranty, use:

Warranty Information

Labor Operation	Description	Labor Time
K7253	Sprag, Forward Clutch - Replace	Use Published Labor Operation Time