PISTON 0993196 - Caterpillar

Illustration 1. Location of new bolts.Adaptable To: The new 8E0270 Transfer Gear Case Assembly is a direct replacement for the former 6T8924 Transfer Gear Case Assembly. The new case assembly is effective with transmission serial number 3TA1350 (528 Skidder) and 1ZC2646 (518 Skidder). The new transfer gear case assembly is adaptable to earlier skidders with the addition of five 0S1590 Bolts and five 5M2894 Washers. The former transfer gear case assembly can be reworked to obtain the benefits of the new transfer gear case assembly by using the following procedure.
Rework Procedure For Former Transfer Gear Case Assembly
1. Remove and completely disassemble the transfer case and cover. Clean and remove any burrs that may be on cover (2) and transfer case (3) mating surfaces. Examine the threaded holes for excessive wear or damage. Repair the holes using Heli-Coils® or Keenserts as needed.2. Examine the dowell fit at both locations. It should be from 0.010 to 0.066 mm (.0004 to .0026") tight in both the cover and case. If the fit is not correct, follow Steps 3 and 4 to improve the fit. If the fit is correct, proceed to Step 5.3. Loosely assemble cover (2) to transfer gear case (3) without the gasket and dowels. Set up the transfer gear case assembly on a machine tool table. Indicate the bearing bores to correctly align the cover to the case. Tighten all cover bolts to hold the alignment.4. Bore the dowel holes oversize just enough to clean them up. Make and fit new dowels to the oversize holes. The fit should be in the range specified in Step 2 [0.038 mm (.0015") tight is the nominal fit].5. With the cover secured to the case using both the bolts and dowels, increase the depth of the upper bearing bore (into the cover) by 0.36 mm (.014"). The finish dimension (A) should be 142.93 0.13 mm (5.627 .005") as shown in Illustration 2. (This compensates for the removal of the gasket and maintains the end play between the straight roller bearings.)
Illustration 2. Depth of bearing bore.6. With the cover secured to the case, drill five 8.2 mm (.323") holes at the locations shown at the top of the cover in Illustration 3. Drill through the cover and case. Since there are no bosses inside the case at these locations, the holes will break through inside the case. Use a 20.0 mm (.80") spotface to clean up the five holes and give a good seating surface on cover (2) for the bolts and washers.
7. Remove the cover from the case. Tap the holes, at least 17.5 mm (.69") deep, in the case with a 3/8"-16 tap. Increase the diameter of the holes in the cover to 10.5 mm (.406") diameter. This will give sufficient clearance for the bolt shanks.8. Thoroughly clean the reworked case and cover.9. After the end play for the two lower shafts has been set, remove any grease from the case and cover mating surfaces. Apply 6V6640 Gasket