Thread: Petrol series starter motor refurbishment

The rust suggests that the starter may have been "poling", in other words, the bushes are worn sufficiently that the armature is sometimes touching the poles. When this happens, it causes a great deal of friction, and will quickly burn out the windings if you keep trying to start even though it is not turning very well. It should be quite easy to tell if this is happening, the armature should spin easily with little friction without brushes (hold it so the weight of the armature is in the direction it would have been pushed by the load on the pinion). Bushes should be available, and perhaps worth replacing anyway seeing you have it apart. I would clean off the rust and give it a thin coat of varnish.

John

after reassembling without the brushes and test spinning it to check the bearings (check the radial run out + axial float)

de rust it very carefully with wet and dry (try not to get the windings wet) then paint the majority of it with a light clear varnish) in areas where sparks get thrown paint the body with liquid electrical tape. do the same for the un-insulated parts of the windings and the brush pack OR strip the brush pack and fit it with heatshrink. rework the brush pack and lubricate the side of the brushes with a very fine smear of carbon greaseensure that the springs and brushes are parallel to each other, perpendicular to the commutator and parallel to the axis of the armature.

then while thats all drying...

mount the armature in a drill or a vice and spin it very slowly while you clean the body and the commutator with wet and dry (1800 grit for the commutator) then with a very fine needle file clean out the gaps between the individual contacts on the commutator.

With that done...

install the armature into the body and then install the brush pack, to install this I cheat abit and use a plastic screw top from a 4l bottle with the center cut out of it to space the bushes out past the commutator

Many thanks John and Dave, and please bear with me here.

What part are you referring to as "windings"?

Should I be insulating the inside of the housing (yoke in the manual) with light varnish/liquid electrical tape (looks like good stuff!)?

Also, referring to the 'brush pack' do you mean the brushes and their leads?

Cheers,

terminology-troubled Sam

Originally Posted by series3

Many thanks John and Dave, and please bear with me here.

What part are you referring to as "windings"? The copper wire wound round the lumps of iron in both the stator (the body) and the armature (the bit that turns).

Should I be insulating the inside of the housing (yoke in the manual) with light varnish/liquid electrical tape (looks like good stuff!)? Yes - the poles should only have a very thin layer of varnish, as they run very close to each other.

Also, referring to the 'brush pack' do you mean the brushes and their leads? Yes

Cheers,

terminology-troubled Sam

Strictly speaking, wet and dry is not suitable for this purpose as the abrasive used on it is conductive - if accumulated between the segments of the commutator it will encourage sparking. Not a serious problem with starters, more so with generators, as they are in continuous operation. Glasspaper is a better abrasive to use, in the absence of a lathe to skim the commutator.

John