For 1990-2009 cars

# LOSS OF DRIVE OR BINDING IN FOURTH GEAR

TRANSMISSION APPLICATIONS: SUBJECT: ------------------------- ------- THM 325-4L 4TH AND OVERRUN CLUTCH REPAIR

TRANSMISSION MODELS: VEHICLE APPLICATIONS: ------------------- -------------------- ALL 1982-1985 ELDORADOS AND SEVILLES (E AND K)

Some 1982-1985 Eldorados and Sevilles may experience a condition of a "binding" feel in 4th gear or a total loss of drive. This condition may be caused by 4th and overrun clutch damage due to transmission lubricating (cooler) oil entering the overrun clutch circuit (causing the clutch to apply in 4th gear) or a loss of lubricating (cooler) oil to the overdrive assembly. Upon disassembly of the transmission, the 4th and/or overrun clutches will appear burned or blued and extensive damage to the overdrive assembly may also be evident.

To repair this condition, use the following procedure:

1. Disassemble the transmission and flush all components.

2. Flush the transmission cooler and lines to remove all debris and contamination. Inspect the transmission cooler and lines for restrictions and replace as necessary.

3. Inspect torque converter for debris and flush. If the failure was extensive, it is suggested to replace the torque converter to prevent contamination after repair.

#### NOTE: If steps 1-3 are not followed, abnormal shift conditions may result after repair.

4. Replace turbine shaft if any of the following conditions are evident on the shaft (refer to Figure 1) :

o Scoring or bluing o Damaged sealing ring surfaces o Collar not firmly seated against shoulder o Lube passage leakage into overrun passage during air check

#### NOTE: Check for leakage with 30 P.S.I. shop air in the #1 overrun passage. If leakage is detected from lube passages, replace shaft.

5. Inspect drive sprocket support and replace if any of the following conditions are evident (refer to Figure 2) :

o Mispositioned turbine shaft bushing obstructing lube passage o Loose or damaged turbine shaft bushing

6. Replace drive sprocket support oil seal ring.

7. Inspect overdrive roller clutch and replace if any of the following conditions are evident (refer to Figure 3):

o Blued or damaged assembly o Damaged or mispositioned energizing springs o Flattened or scored rollers

8. Inspect case to case cover mating surface and replace case if distorted or damaged (refer to Figure 4).

9. Replace case cover using the following procedures to install the sprocket supports to minimize case cover distortion (refer to Figure 5):

o Using a two-ton arbor press, support the case cover at the sprocket support hole using an appropriate tool such as a plastic pipe (refer to Figure 6). o Install sprocket support gasket and position sprocket support into case cover hole. o Use the sprocket support bolts as guides by installing the bolts approximately three to four threads deep. o Ensuring sprocket support is aligned and straight in the hole, press the sprocket support into the hole using even pressure until the support is firmly seated. The support should move smoothly into position during this operation.

#### NOTE: Damage or distortion may occur to the cover if the sprocket support is forced into position.

o Torque attaching bolts to 24 N-m (18 ft. lbs.).

10. Inspect all transmission components and replace or repair as necessary. Reassemble transmission per appropriate Service Information Manual.

11. Set turbine shaft endplay at 1.02 mm - 1.27 mm (.040" - .050") which is toward the maximum side of this specification (published specification is 0.76 mm - 1.30 mm or .030" - .051") .

12. Air check 4th and overrun clutches to ensure proper operation.

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.