How to replace transmission in a Dewalt Hammer Drill

Just received the new transmission for the Dewalt DC925, and I am about to get it installed.

The first thing I do is to remove the chuck and spindle assembly, so I unscrew the four Torx-10 screws:

Removing screws

By doing this I have access to the transmission. I take it out and compare to the new transmission:

Old transmission (left), new transmission (right)

They look identical, so it's time to get the new one installed. Before I do that, I decide to remove the lithium grease that I added last week to the spindle and use instead a silicon grease that came with my SDS Rotary Hammer which seems more appropriate for this.

Now it's time to attach the spindle assembly with the new transmission to the motor:

Closeup of the motor shaft

Now in order to get the transmission mounted to the motor shaft, I have to slightly press the drill switch so the shaft turns and it engages the transmission gears. Then I put the screws back and the drill is ready for a test.

Unfortunately the problem when changing gears is still there, so I am starting to think that it is not a problem but a "feature" of the drill. I will have to investigate that. The good thing is I have an extra Dewalt transmission just in case.