How to Replace the Transmission on a DeWALT Cordless Drill

Transmission trouble? It's time to face the fix. Whether you are a master carpenter or an occasional drill-seeker, eReplacementParts.com provides the parts, procedures and facts you need to fearlessly fix what fails you.

The transmission accomplishes two primary tasks inside your cordless hammer drill. First, it converts the (high RPM) output from the motor into (low RPM) torque. Second, it contains the gear shift lever for the high, medium and low speed gears. When the transmission goes bad in your hammer drill, you'll likely notice decreased rotation at the chuck (spindle) despite sufficient output from the motor.

You may also notice one (or more) of the speeds in the gearbox quits working. Be careful not to confuse these problems with a gearbox (selector switch) that is simply "stuck" between gears, because this will produce the same type of symptoms.

This article provides step-by-step instructions for removing and installing the transmission on a DeWALT cordless hammer drill.

Let's get started.   REMOVING THE TRANSMISSION [top] 1. Remove the battery.

Remove the battery from the drill.

  2. Remove the end cap.

Remove the (4) screws from the end cap.

Remove the end cap from the drill.

  3. Remove the gear case assembly.

Remove the (4) screws from the gear case assembly.

Separate the gear case assembly from the motor housing.

  4. Remove the top half of the clamshell (housing).

Remove the (5) screws from the clamshell assembly.

Lift the top half of the clamshell (housing) away from the lower half.

  5. Remove the transmission.

Use one hand to hold the motor assembly in place within the lower housing.

Lift and separate the transmission from the motor assembly.

  INSTALLING THE NEW TRANSMISSION [top] 6. Install the new transmission.

Remove the rubber band (if equipped) from the new transmission assembly.

Align the gears of the new transmission with the pinion gear (on the motor).

When properly aligned, the transmission/motor assembly should “lock” into the housing.

  REASSEMBLING THE UNIT [top] 7. Reinstall the top half of the clamshell (housing).

Install the top half of the clamshell (housing).

Secure the clamshell assembly with the (5) screws.

      8. Reinstall the gear case assembly.

Install the gear case assembly.

Rotate the spindle shaft (chuck) until the gear box aligns (snaps into place) with the motor housing.

Secure the gear case to the motor housing with the (4) screws.

  9. Reinstall the end cap.

Install the end cap.

Secure the end cap with the (4) screws.

  10. Reinstall the battery.

Install the battery.

As you just learned, fixing things yourself means more drilling with less billing. Hopefully, this article has restored your ability to drill holes without replacing your whole drill. And that's just the tip of the bit. Our online repair guides can help expand your skills far beyond drills; empowering you to face power tool problems whenever they arise; and to fearlessly fix whatever fails you.

Find your next fix here.   [top]