Differential Housing Repair

This is a photo of a repaired Caterpillar differential housing.

In this housing, the threaded holes that are used to retain the gear assembly access cover had become damaged over several years of use.

Keensert thread inserts were used to repair the damaged threads.

Here are the details of this repair project...

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Unique Challenges:

This is a close-up view of a solid model of the differential housing.

One challenge that made this particular repair difficult to accomplish was the close proximity of the threaded holes to the pilot counterbore in the housing (as shown in the detail view).

The counterbored surface needed to remain intact after the repair was complete.

Also, the repaired housing needed to be able to retain gear lubricating oil, without leaking, once assembled.

Differential Housing Repair Process
Step 1:

Each of the original damaged holes were drilled, countersunk, and tapped to accept a Keensert thread insert.

Note that the oversized tapped holes broke into the counterbore pilot surface, as shown here.

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Step 2:

A new Keensert was threaded into each of the newly-tapped holes.

In a typical Kennsert installation process, the top of the insert is slightly recessed below the top surface of the workpiece.

In this application, however, the tops of the inserts were installed flush with the surface of the flange to help minimize the possibility of oil leakage at those locations.

Also, to help prevent oil leakage, each the inserts were installed using Loctite threadlocker compound.

Note that, when installed, one of the four locking keys of each insert was located in the area of the differential housing pilot counterbore.

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Step 3:

In this step, the Keensert locking keys were driven-in to lock the insert into the housing.

As shown in this view, the locking key that was located in the area of the counterbore was removed, and not used.

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Step 4:

Once all of the Keenserts were installed, the differential housing pilot was machined to remove the portions of the inserts that extended into the counterbore, as shown here.

As a last step, a two-part epoxy repair compound was used to fill the slot in each of the Keenserts where the locking key was removed - to help prevent the possibility of oil leakage around the insert at that location.

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Completed Repair:

This is the model view of the completed repair.

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This is a photo of the actual completed differential housing repair project.

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