How to Weld My Lawn Mower Rear-End Differential

Arrange your work area. Decide how you are going to weld the differential -- either on a non-flammable work surface or in a vise.

Place the differential gear system on a clean and clear work surface. Remove the housing from the differential by unbolting the shim locks. Remove the bearing caps with the shims.

Loosen the top hat bolts and take off the top hat, exposing all of the spider gears. Remove the spider gears from the differential. Clean the gears with brake cleaner to remove any oil and dirt that may contaminate the welds.

Place the spider gears on your work surface or in a vise. Put on your safety equipment that includes a welding cape, gloves, safety glasses, particle mask and auto-darkening helmet. Turn on the welding torch.

Weld a small bead in one of the valleys between the teeth of the spider gear. The bead in the valley should not be equal to the top of the two teeth due to clearance issues when you reassemble the differential.

Skip the valley next to the one you have welded and move on to the one beside it. Once you have welded this valley, skip the next two valleys and weld a third valley. Skip one valley and weld the one next to it. Skipping two more valleys will bring you back to the first valley. Of the ten valleys in the spider gear, four of them should be welded.

Repeat the welding process for the remaining spider gears. After all the gears have been welded, set them aside to cool until they are cool to touch.

Reassemble the differential, reversing the order that you used to disassemble the unit.