How to Replace the Motor Brush Holder on a Makita Grinder

Brush holder hardly holding? It's time to face the fix. Whether you are a master mechanic or a garage-based grinder, eReplacementParts.com provides the parts, procedures and facts you need to fearlessly fix what fails you.

The brush holder serves several critical roles inside your grinder. First, as the name suggests, it “holds” the carbon motor brush in alignment with the armature. Second, it contains the brush spring, which applies downward pressure to the motor brush; ensuring continual contact (and continuity) with the commutator. Lastly, it provides the wire connections for the brush lead, as well as the incoming power to the brush holder itself.

Damage commonly occurs to brush holders when the grinder motor is overheated. This can cause the metal to distort. Overheating can also destroy the temper of the metal brush spring, which reduces its ability to hold the motor brush firmly against the commutator. Replacing the brush holder is very easy to do; especially when you follow the steps below.

This article provides step-by-step instructions for removing and installing the brush holder on a Makita grinder.

Let's get started.   REMOVING THE BRUSH HOLDER [top] 1. Remove the side handle.

Unscrew and remove the side handle from the grinder.

  2. Remove the guard.

Loosen the lock-screw on the guard assembly.

Rotate the guard assembly to disengage it from the housing.

Remove the guard from the grinder.

    3. Remove the rear cover.

Remove the (1) screw from the rear cover.

Slide the rear cover away from the motor housing.

  4. Disengage the brush spring.

Use a pick to (gently) lift the brush spring from the back of the carbon motor brush.

Reposition the brush spring alongside the motor brush (against the brush holder).

  5. Remove the carbon motor brush.

Disconnect the brush wire from the terminal on the brush holder.

Slide the motor brush out of the brush holder.

  6. Disconnect the field (wire).

Disconnect the field wire from the brush holder (this wire is often black).

  7. Remove the brush holder.

Lift and reposition the brush spring back into the (now empty) slot on the brush holder.

Remove the (2) screws from the brush holder.

Lift the brush holder out of the motor housing.

  INSTALLING THE NEW BRUSH HOLDER [top] 8. Install the brush holder.

Install the new brush holder into the motor housing.

Reposition the brush spring (as necessary) to access the mounting hole.

Secure the brush holder with the (2) screws.

  REASSEMBLING THE UNIT [top] 9. Reconnect the field (wire).

Reconnect the field wire to the terminal on the new brush holder.

  10. Reinstall the motor brush.

Reposition the brush spring (as necessary) to access the slot for the motor brush.

Install the motor brush into the brush holder.

Connect the brush wire to the terminal on the holder.

Reposition the brush spring against the motor brush.

  REPEAT (AS NECESSARY) [top] 11. Repeat (as necessary).

Your Makita grinder has two motor brushes (and two brush holders). These are located on opposite sides of the motor housing. The steps are the same for both sides. Inspect and replace the second brush holder (as necessary).

  12. Reinstall the rear cover.

Visually inspect the wires for potential “pinch-points” and adjust/tuck the wires as necessary.

Slide the rear cover onto the motor housing.

Secure the rear cover with the screw.

  14. Reinstall the guard.

Install the guard assembly onto the grinder.

Rotate the guard assembly to engage the mounting plate.

Secure the guard with the (1) screw.

  15. Reinstall the side handle.

Install the side handle onto the grinder.

Tighten the side handle until secure.

You can't place a value on a job well done, unless you did it yourself. (Which you did.) Now you can place that value back into your own pocket. (Or into your business.) Not only did you refine your grinder at a fraction of the cost of replacement; you have expanded your skills far beyond the daily grind.

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