Usage:
784B (5RK) Tractors;
785 (8GB),
785B (6HK),
789 (9ZC),
789B (7EK),
793 (3SJ),
793B (1HL) Trucks
Reference: Service Magazine; July 8, 1993; Page 3; "Procedure To Prevent Rear Wheel Bearing Cones From Rotating On Axle Housing" for 776B Tractors; 777B, 785, 789 Trucks.
Reference: Guideline For Reusable Parts, SEBF8083-02, Procedure To Repair Worn Wheel Spindle And Hub for Off Highway Trucks.
Description of Change: Improved wheel bearing cone anti-rotation system prevents wheel bearing cones from rotating on the axle housing. The rotation could occur when the ball used to keep the cone from rotating is damaged.
Adaptable To: The new parts used in this change are shown in Charts 1, 2 and 3. Part numbers listed under the heading "Phase II Part No." represent current production. Part numbers listed under the heading "Phase I Part No." are the original parts used with the "retaining pin" retention system. Both Phase II and Phase I parts utilize the "retaining pin" type retention system and are identical except that the following Phase II parts have increased in hardness: axle housing, seal retainer, final drive reaction hub and retainer plate. Part numbers listed under the heading "Former Part No." are the parts previously used with the "ball" retention system. This change is effective with 784B (5RK13) Tractor and 785B (6HK220), 789B (7EK195), 793B (1HL72) Trucks. Earlier machines can be reworked by using a 106-9612 Retaining Pin, 107-8543 (785), 107-8487 (789), 107-8485 (793) Seal Retainer and following the procedure below.
NOTE: An undersize bearing cone is available for the axle housing outer wheel bearing station on the off highway trucks covered in this service magazine article. The undersize cone provides an alternate means (other than spray metalization) of reconditioning an axle housing that is damaged at the outer bearing station.
The undersize bearing cone part numbers are included in Charts 1, 2 and 3.
The outer bearing axle housing journal diameter, and the "over the axle housing" retaining pin projection dimension for the under size bearing journals are shown in Chart 4.
Illustration 1. Rear Wheel Group
Procedure To Rework The Axle Housing To Accept 106-9612 Retaining Pin and 107-8543 (785), 107-8487 (789), 107-8485 (793) Seal Retainer.
NOTE: Reworking axle housings to utilize a ball to keep the bearing cones from rotating is
NO
longer recommended.
NOTE: SEBF8083-02, see "Reference", allows an axle housing diameter wear limit of 0.20 mm (.008 in) for reuse. To check for reusability, install the new bearing cone on the axle housing bearing journal and measure the clearance between the six o'clock (lowest) position of the bearing cone and journal using feeler gauges. A clearance of less than 0.20 mm (.008 in) is acceptable. See "Note" on utilizing an undersized cone.
NOTE: Dimensions "A" through "D" specify the spindle slot size for both the inner and outer bearing races. Dimension "E" is the length of the outer race retaining pin slot. Dimension "F" is the dimension from the end of the axle housing to the outer retaining pin slot. Dimension "G" is the diameter of the outer bearing race. Dimension "H" is the dimension over a properly installed outer race retaining pin and should be used as a reference before re-assembly. Dimension "J" is from the axle housing seal retainer flange to the inner race retaining pin slot. This dimension is 5.0 mm (.02 in) less than was previously recommended and moves the inner race slot towards the machine center line to prevent interference between the retaining pin and the seal retainer. Dimension "K" is the length of the inner race retaining pin slot. Dimension "L" is the dimension over a properly installed inner retaining pin and should be used as a reference before re-assembly. Dimension "M" is the diameter of the inner bearing race. Dimension "R" is the diameter of the undersized outer bearing race. Dimension "Q" is the dimension over a properly installed undersized outer race retaining pin and should be used as reference before re-assembly.
Illustration 2. Slot end view. Section through slot in axle housing bearing race.
Illustration 3. Axle housing outer race.
Illustration 4. Axle housing inner race.
Machine slots in the axle housing using the dimensions shown in Chart 4 and Illustrations 2, 3 and 4.
Illustration 5. Outer bearing cone slot profile.
Illustration 6. Inner bearing cone slot profile.
If new or low hour 8E-7917 or 8E-7918 (785), 8E-7919 or 8E-7920 (789), 8E-7921 (793) Cones are used with this procedure, cone slots may need to be modified for use with the retaining pin system.
Illustrations 5 and 6 specify the correct bearing cone slot profile. Remachine slot if needed to maintain slot length (Dimension N) and maximum radius (Dimension P). The cone slot must be machined with a blunt end mill cutter or equivalent to provide a proper fit between the pin and the slot.
NOTE: To avoid heat distortion of cone race use slow feeds and speeds.
Illustration 7. Outer race or undersized dimensions.
Illustration 7, Chart 4 and Chart 5 shows the dimensions for an undersize axle housing. Also see Illustrations 2, 5 and 6.