Page updated
February 2004

How to Clean/Service Electric Motors

Motor maintenance

Always read and follow any instructions that come with a new motor.

Opinions differ about what to do and how often, but if the motor is clean, (physically and electrically) it will be more efficient.
Most motors are 'rebuildable' - two screws permit the end-bell to be removed so that the armature can be extracted.
Some motors (normally those supplied with the car as part of the kit) have no screws, so the end-bell cannot be removed.

The cleaning procedure is very similar, but more care is required with a fixed end-bell to ensure that the motor is completely clean.

Always ensure that a tray or other suitable container is available to hold the small components before dismantling the motor!

click here for rebuildable motors.

click here for non-rebuildable motors.

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How to clean motors that are rebuildable -

Remove the brush springs and withdraw the brushes

Loosen and remove the two screws - be careful to retain the washers and spacers.

Pull the the bell-end from the shaft - carefully!. Look for spacers/shims from the armature shaft as they may remain attached to the inside of the bell-end or fall out. Check and retrieve.

Remove the armature from the casing - care! there are shims or spacers at the other end of the armature shaft as well. Check and retrieve.

Clean the motor and casing with motor spray. Do not spray onto the brushes.

If required, re-cut or 'skim' the cummutator using a motor lathe.

Wipe the commutator with a clean cloth or tissue which has been soaked with motor cleaner.

Wipe the brushes with a clean dry cloth or tissue

Reassembly

Replace all spacers and shims on the shaft exactly where they came from
Oil the bearings -
For 'standard' motors with solid bush-type bearings - Apply a small quantity (one drop) of oil to each end of the shaft just before re-assembly into the bush.
For 'modified' and '19 turn' motors with ball-race bearings, oil the ball race not the shaft.
Replace the bell end and ensure that the screws are 'firm'
Test the 'end-float' by moving the shaft in and out. Movement of 1 or 2 mm is desirable. Too much end float will be indicated by a wavy line of 'wear' on the commutator.
Add shims if necessary and re-test.
Renew the brushes if they are pitted or if the commutator has been skimmed.
Polish the commutator with a cleaning 'stick' - unless it has been skimmed.
Replace the brushes in their holders. Be careful to ensure that the brushes move freely and that the springs are positioned in the centre of the brush.
TEST THE MOTOR

If brushes have been replaced, new brushes should be 'run-in' at low speed for about 5 minutes. Back

How to clean motors that are not rebuildable -

Most motors that come with the car kit are of the 'non-rebuildable' variety - the 'bell-end' has no screws to enable it to be separated from the rest of the motor.
Cleaning principles are the same as for 'rebuildable' motors, but extra care is needed to ensure debris is removed and the oil is where it is needed.

Remove brush springs and withdraw the brushes
Squirt motor cleaning spray through the whole motor until the fluid coming out is clean.
It may take some time to remove the dust
Don't spray onto the brushes.
Allow to dry.
Soak one end of a cotton bud with motor cleaner and insert it into a brush holder.
Rotate the motor by hand with the cotton bud pressed against the commutator.
Remove the cotton bud and allow the motor to dry.
To polish the cummutator, insert a special cleaning 'stick' into a brush holder and press it against the commutator while rotating the motor.
Wipe the brushes with a clean cloth or tissue - OR replace with new brushes if pitted
Apply a very small quantity (one drop) of oil where the motor shaft shows at both ends.
Spin the motor by hand in order to work the oil in.
Reassemble the brushes and springs - be careful to ensure that the brushes move freely and that the springs are positioned in the centre of the brush.
TEST THE MOTOR!

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