Motor Pulley Mod

This is my first time building an E Board and I came on to a problem, the pulley that I got for my board has a 10mm hole and the motors that I bought have a 8mm shaft so after trying to buy for the second time a new pulley, the site that i tried to order the pulley never shiped it to me and after the second atempt I decided that I would fix the problem myself and save some money in the process

Lets start

First the problem 20190506_225525 20190506_225540

Has you can see the pulley is too big for the motor so I had to come up with a solution

And here it is

After a trip to the shop I bought this 20190508_163301 A stainless steel pipe with and outer diameter of 10mm and a inner diameter of 8mm

The step back

The pipe is a bit to big for the hole


After a bit of filing, I was able to make the tube enter very snuggly and I had to use a vise to force the tube in 20190506_225614 20190506_225656

But there is still the problem of the screw holes for the mounting screws

So after a drill the holes with a 3mm drillbit I had to go again to the store to buy to buy some 4mm tapping holes tips and hand tap the holes " didn’t have any 4mm tips" 20190508_163500 20190507_185809

After a bit of filing to clean the holes

Success! It all fits together! 20190506_225727 20190507_193308

Give me your opinion on what you think of this mod Hope you guys like it


You didn’t really explain what you are doing with the rod but it looks like you are going to replace the motor shaft with it? If so just order a pulley that fits your motor shaft, it will save you a lot of time and effort and might keep you from breaking your motor

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No he has a motor with 8mm shaft and a pulley with 10mm bore. Hes using the pipe as a adaptor.


No key way in the pulley right? Use red loctite on both the pipe and shaft. Remember to drill 1 or 2 holes in the pipe for the set crews.


That’s exactly what I did, my pulleys don’t have a key way but they have two screw holes and I already got the loctite, when i finish my build I will post it, do you think it will hold?


Yeah of you let the glue cure for at least 24h you’re golden

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I’d just get some steel motor pulleys from @marcmt88

If it works it ain’t stupid. I would suggest you get pullies with an 8mm boar, as you will likely have balance issues but I bet they wont be bad and it’ll likely work forever. Good job.


I’ve done exactly this and used the setup for over 1000km. There won’t be any balancing issue if there’s no gap between the shaft and adaptor.

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This is pretty common in robotics, I use it for 6mm to 3/8" all the time and it never failed

My aluminium motor pulley wear out after 100km. I will not advice use red loctite with it )

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I have done this before with 6mm shaft and 8mm pulleys. I just drilled and tapped the pipe and added a longer grub screw to go through both. It works great. 1 drop of loctite for it and it was permanant

great post… I was wondering the same thing… it looks like Loctite is a must for all E-builds and on every screw… good to know

Hi Duarte, I believe you live in Portugal and are Portuguese. Well, i use to live in the US, but now i live in Portugal also. I’m also building a Trampa based e-MTB. Just finished building a twin jet surfboard. It is great to know there is people near by that enjoy making the same stuff. My email is [email protected] It would be nice to exchange knowledge.