A/T - Changing a Dual Sump Into a Single Sump

TSB: 87-45 (July)

SUBJECT: Changing a dual sump into a single sump

Probably the most common failure on the early type dual sump units is pinion bearing failure, because of low fluid level in the differential section of the transmission. Changing a dual sump transmission to a single sump transmission may be an inexpensive way to save a damaged case and/or prevent a repeat failure.

Use the following steps:




1. Create a hole in the case approximately the same size the single sump units have. Use the figure as a guide.




2. Using a file, remove approximately 1/8 inch of material (the thickness of 2 quarters from the pump 0-ring surface of the case, going up from the hole created. (See figure)




3. Since early type washers for side gears have no tabs, they can spin with the side gears and slight metal contamination may result. If the differential installed the early type washers (See figure), install a magnet in the pan to catch any metal contamination.

4. Use the late type pump gasket, Part # 4269661




5. Plug the differential vent.





6. Do not install transfer shaft metal clad seal in the transfer shaft bearing retainer. Always install new 0-rings on the outside of the transfer shaft bearing retainer.

The purpose of the O-rings will be to prevent the transfer shaft bearing retainer from spinning in the case.

7. Use the late type deep pan, part # 4431538, dipstick part # 4295947, and late filter, part # 4269649