A/T - THM 325-4L Loss of Drive/Binding Feel
88cad01Bulletin No. T-88-66
File in Group 7
Number 177
Corp. Ref. No. 517101
Date Jan. '88
SUBJECT: 4TH AND OVERRUN CLUTCH REPAIR - THM 325-4L
MODELS AFFECTED: 1982-1985 ELDORADOS AND SEVILLES
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 overrun 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.
FIGURE 1 - TURBINE SHAFT:
4. Replace turbine shaft if any of the following conditions are evident on the shaft (refer to Figure 1):
^ Scoring or bluing
^ Damaged sealing ring surfaces
^ Collar not firmly seated against shoulder
^ 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.
FIGURE 2 - DRIVE SPROCKET SUPPORT:
5. Inspect drive sprocket support and replace if any of the following conditions are evident (refer to Figure 2):
^ Mispositioned turbine shaft bushing obstructing lube passage
^ Loose or damaged turbine shaft bushing
FIGURE 3 - OVERDRIVE ROLLER CLUTCH:
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):
^ Blued or damaged assembly
^ Damaged or mispositioned energizing springs
^ Flattened or scored rollers
FIGURE 4 - CASE COVER MATING SURFACE:
8. Inspect case to case cover mating surface and replace case if distorted or damaged (refer to Figure 4).
FIGURE 5 - INSTALLING SPROCKET SUPPORTS:
9. Replace case cover using the following procedures to install the sprocket supports to minimize case cover distortion (refer to Figure 5):
FIGURE 6 - SUPPORTING CASE COVER:
^ 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).
^ Install sprocket support gasket and position sprocket support into case cover hole.
^ Use the sprocket support bolts as guides by installing the bolts approximately three to four threads deep.
^ 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.
^ 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 .040" - .050" which is toward the maximum side of this specification (published specification is .030" - .051").
12. Air check 4th and overrun clutches to ensure proper operation.
For warranty purposes, use Labor Operation T6251 at 7.5 hours. If case is replaced use Labor Operation T6252 at 8.1 hours.