How to Lubricate the Internal Gears of a Gear Hub Motor

Gear hub motors are quiet workhorses — until the internal gears run dry. If the operating noise of a brushed or brushless gear hub motor suddenly increases, the gears need attention. Here is how to service them without creating new problems.

Before You Open the Motor

Clean the work area and the motor surface first — any debris drawn onto the magnetic steel ring will cause trouble later. Mark the relative position between the end cover and the hub before loosening anything, and loosen the screws diagonally (in a star pattern) to prevent the motor housing from deforming.

Lubricating the Internal Gears

Once the motor is disassembled and the fault has been fixed, coat all tooth surfaces of the gears with lubricating grease — generally No. 3 grease, or the lubricant specified by the manufacturer. Skipping this step is what causes the rising whine that brought you here in the first place.

Reassembly Checks

• Use the original end cover code/marks when reassembling to prevent chamber sweeping (rotor rubbing) after reassembly.
• On brushed motors, check the spring tension inside the brush holder, confirm the carbon brushes do not bind or collide in their holders, and seat the brushes correctly against the commutator to avoid damaging the brushes or holders.
• Before final assembly, clear all debris from the motor components, and fix the hub body firmly so parts are not pulled together or damaged by magnet attraction.

Motor Types: A Quick Reference

What is a motor? The component that converts battery electric energy into mechanical energy and drives the wheels of an electric vehicle.

What is a brushed motor? A motor in which coil current direction is reversed mechanically by the commutator and carbon brushes; the magnets and brushes stay fixed while the coil and commutator rotate. Brushed motors come in high-speed and low-speed versions.

What is a brushless motor? A motor in which the controller supplies DC in alternating directions to reverse the coil current internally — there are no brushes or commutator between rotor and stator.

What types are common? Brushed and brushless gear hub motors, gearless hub motors, and side-mounted (mid-drive) motors.

Regular lubrication, careful disassembly and clean reassembly will keep a gear hub motor quiet for years. Looking for a new unit? See our spoke motors or the wider moped and scooter motor range.