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Below is an image of the situation I am trying to resolve. What you can see is the following:

  • The black triangly shape is the rest of the clutch shoe assembly of a centrifugal clutch. It is pressed onto the shaft of the rotor of an electric starter
  • The rest of the image is the electric starter. It has a conic structure where the black tringle is pressed upon.

I am trying to remove the black triangle from the starter. Apparently last time I have installed it I might have overtorqued it a bit because I have been completely unable to get any hold of it.

Now what makes my situation a bit more tricky is that the piece I want to remove is pressed onto the rotor of a brushless motor - the copper windings and the black part is hovering inside a very strong permanent magnet, but it is not actually attached to anything. So just hammering on it will simply push the rotor out of the stator, there is nothing holding it back.

All my attempts described below were also done using generous amounts of penetrating oil to make sure it is not rust or anything else essentially sticking the pieces together except just the normal pressing.

I already tried to put a bolt through the rotor, put a nut on the other end and put the nut in a vice and then using a lever and a hammer trying to lift it of. No chance. All it did was bending the extremely strong lever I used on the triangle.

I also tried to heat up the triangle with a blow torch but I am very limited as it is in very close proximity to the copper windings which have insulation that would break down with too much heat essentially rendering the whole thing useless.

I have 3d printed a flywheel puller where I can fix it to ther outer casing, put a bolt through the middle to fixate the rotor to the external case and then have 3 screws go into the holes of the triangle. It worked in terms of properly fitting and creating pressure on the triangle without moving the rotor, but it is stuck so badly that even an inch thick completely solid PETG eventually snapped in half.

I am really lost, are there any other options to get rid of this?

Image of clutch shoe stuck on electric starter shaft

3 Answers 3

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Instead of trying to shoehorn something into the small space inside the motor housing, pull the whole thing out of the housing and have plenty of room to work on it. Once it's out of the housing, a gear puller will have plenty of room to work.

Once you've got the clutch shoe removed & replaced (assuming replacement is part of the process), put the windings back into the motor housing. As you said, it's held in place by nothing but magnets.

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  • Thats what I ended up doing and it worked. It was actually also the first thing I had planned to do, but after trying to remove it I thought it was stuck - i.e. it cannot be fully removed, so I had abandoned the idea. I gave it another shot and the magnets are just way stronger than I thought, eventually I managed to press it out :) Commented Mar 13, 2022 at 9:07
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3D print will not be strong enough.

Buy/rent a gear/flywheel puller, don't waste time trying to hack something up. Local garage probably do it for a few bucks or a beer.

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  • Yea, I actually do have a flywheel puller, but it is too big to fit this construction. But yea, I am going to the garage tomorrow where I know some people, maybe they have a tool that fits. Commented Mar 8, 2022 at 21:22
  • Unless the 3d print was made of metal, but that's obviously not the case.
    – FreeMan
    Commented Mar 9, 2022 at 15:54
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Apart from having two small pullers - one designed specifically for pulling battery clamps I would make one.

I would be using a thick steel washer drilled for the 3 bolts and use a suitable diameter punch to push on the shaft end.

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  • That is a good idea, I already have a design in mind with a big washer to reinforce the 3d print. If the garage cant help me tomorrow I am going to try it Commented Mar 8, 2022 at 21:50

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