View Full Version : How do you fit a pinion to a micro motor?

11-01-2005, 09:44 PM
Hi all,

just ruined a 370 micro fireball that was destined for my decathlon. don't ask how i'm very annoyed :mad:

next time, assuming i can be bothered to go through the process of ordering a motor from your side of the pond, wait ages for it to arrive and source another new pinion for it from a different supplier...

how should i go about fitting it please?

cheers, Bug.

11-01-2005, 10:42 PM
you can heat the pinion and then press on and loctite, brace the main shaft against something solid and tap with hammer and block of wood or even drill out the pinion if you choose.

removal is easy with the pinion removers.

i go the heating option and tapping. as you get down the shaft apply a collet and spacer (alum tube for instance) and keep on tapping.

Matt Kirsch
11-02-2005, 01:51 PM
I'm betting you probably clamped the motor in a vise and proceeded to drive the pinion on with a hammer, at which point you probably drove the back end right out of the motor?

The most important thing to do is support the main shaft of the motor from behind, on something that it can't penetrate (i.e. not wood or plastic). Pinions can be driven on with a hammer, but CAREFULLY. No wailing away with the 3lb lump hammer.

If you have a machine vise that isn't all horked up like my Dad's from years of welding and other asundry abuse, or a drill press vise, you can use it as a press to push the pinion on too. There are also special pinion press tools available.

Just remember to not put any pressure on the motor's case. Support that main shaft.

11-02-2005, 09:42 PM
Nearly... but not quite.

Supported the motor shaft no problem, used a rubber mallet then a very small socket once the pinion was flush with the top of the shaft... and the shaft bent.

think i'll have to use a machine press or something next time, as suggested, thank you.

I'm just not sure i will buy another motor to be honest, i think i'll just end up flying the stryker and forget about the decathlon (i have the decathlon, stryker and mustang from a job lot from ebay)...

then again, the decathlon owes me a bit too much to just abandon... oh well, we'll see.


Dr Kiwi
11-03-2005, 05:14 AM
Here is the best way to press a pinion on, supporting the rear end of the shaft with a spacer if need be:

Cheers, Phil

11-05-2005, 06:13 AM
if you have a drill press you can press the pinion on real easy.
tighten down the chuck till it's a slip fit over the motor shaft, start the pinion on the shaft. a slight radius on the motor shaft will help here.
place the back of the motor shaft in "something solid". the drill press table. or a piece of steel, anything that will support the shaft. set the motor under the chuck and lower the quill till it touches the pinion. get everything lined up and press the pinion into place. sometimes it's handy to have an extra set of hands but once you have done it a time or two it's easy.