How to Replace Prop Shaft on Brushless Outrunner - RC Groups
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Oct 14, 2009, 02:15 PM
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How to Replace Prop Shaft on Brushless Outrunner

I have searched and searched for info on exactly how to replace a bent prop shaft on an outrunner moter - and found very little in the way of specifics. In my experience, most outrunner motor companies seem to have a press-fit shaft - meaning they do not easily slide out. So, how do you get it out??

I have asked Hyperion and Scorpion this question, and have had very little detail in the way of responses. So - if you want something done - do it yourself, right? So here I go...

If anyone has comments, criticisms, better ideas, better pictures, or free beer, please post, as we'll all learn from this. Thanks for looking and I hope I can help at least one other frustrated flyer. Cheers!

Please see all the pictures, as they do more for the explanation than my words can. I happened to get the miscellaneous items at Home Depot.

PS This has been EDITED 10/15/2009 to incorporate a better method and also input from Lucien at Scorpion.

1. The motor I'm working on here is a Scorpion 3014-18. After you remove grub screws and pull apart the bell with the shaft proceed with the following:

2. I used a 1 ton arbor press from Harbor Freight - $54 after tax

3. For this motor I used a 1/2" pvc pipe coupler and a 3/4" x 1/2" flush bushing -both sch40 PVC. I found I liked the shorter flush bushing better (the latter).

4. Put some oil in the hole to lubricate the opening to allow the shaft to come out and not gall the aluminum of the bell opening.

5. You can see in the picture that after you lower the arbor and press the shaft out, a little bit is still left in the bell.

6. To press the remaining bit of shaft out, I used the pin supplied in a $2 hinge.

7. OK, now that the shaft is out, there's only one thing left to do - put a new shaft in!

8. I changed this part drastically, from the last post before the edit, to again reflect Lucien's input and just make the process much simpler.

9. I used a wooden pole support in which I had to drill a larger hole to allow the tip of the bell to slide through.

10. I trimmed a washer to fit in the wooden pole support to protect the outside of the bell.

11. Now, just put the shaft in the hole, and press it through, ensuring alignment. Probably best to put some additional oil in the opening to allow shaft to slide easier.

BTW motor companies - this guide is not perfect, but it's something. It took me 55 minutes, as of now, to take the pics, upload them, and write this small how-to. Can't you do better?
Last edited by Tick Tock; Oct 15, 2009 at 04:06 PM.
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Oct 14, 2009, 02:50 PM
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manuel v's Avatar
Tick tock

Thanks for sharing your photos.
I hope not any problem.
I Included this tread on mine How to repair an Electric Motor.

Manuel V.
Oct 14, 2009, 08:10 PM
Innov8tive's Avatar
Sorry for not replying sooner, but I have been a little busy here doing repairs on people's motors!

I use the same Harbor Freight Arbor Press that you show in the above photos. I use a similar process to take the motors apart. I have a piece of hard rubber sheet with a couple different size holes punched in it to lay on the table of the arbor press to keep the face of the motor from getting scratched when I push the shafts back in.

I also have a couple of aluminum supports that I turned on a lathe that the motors slide down on to support them when I push out the shafts. These work quite nice if you have access to a machine shop or have a friend that does. Granted, this is a bit of overkill for changing 1 shaft, but when you do it every day, tools like these come in very handy.

Your idea of using the plastic is a good one, however, you need to make sure that the ends are cut perfectly square to make sure everything stays in alignment. Using a power miter saw to make the cuts will ensure that they are cut off square. Another alternatice would be to use a straight pipe coupler, normally uses to glue two pieces of pipe together. These are usually a heavier wall, and come molded square from the factory, so you know that they will work well. They come in 1/2", 3/4" 1" and larger, so you can find a size to fit your motor.

Also, be sure to put a couple drops of oil on the end of the shaft and in the hole in the housing before you push in the shaft. This will help prevent galling of the aluminum due to the high friction of the parts slipping together.

Thanks again!

Lucien Miller

Innov8tive Designs
Oct 14, 2009, 08:53 PM
Registered User
Great advice Lucien! I like the idea of the straight pipe coupler. What do you use to push the final bit of the shaft out?

Oct 15, 2009, 04:08 PM
Registered User

Edited for clarity and new methods

Edited for clarity and new methods 10/15/2009

Oct 15, 2009, 09:33 PM
Registered User
This is very helpful - thanks so much!

One question - have you experimented with heating the bell as suggested by Dave from Hyperion? Not even sure how one would do that - soldering iron, perhaps? It may alleviate stress on the bell as you press the shaft.

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