Looking inside the motor:
To open the motor, first remove the thin 17mm nut on the right side (rear motor: remove the spacer tube as well). Then unscrew the 6 cross-head screws around the perimeter of the shell on the left side. The motor should then slide out of the hub shell – you might need to give a gentle tap to the right axle. It will now look like this:
If you want to send the motor back to us, but don’t want to send the entire wheel, then this is a good stage to stop. If you want to carry on, then undo the 5 cross-head screws shown. These are the non-recessed screws – NOT the 4 recessed screws around the axle.
The gearbox will now open up – this is a tight press fit, so you will probably need to pry it gently with a flat-bladed screwdriver. Work around the gap, prying a little at a time, until it pops open. It’s easier if you have the motor axle in a vice to do this. It will now look like this:
As you can see, the motor has a small steel gear on it, which drives a larger spur gear. On the 200W motors, this spur gear is made of nylon to keep down the noise. This nylon is very durable, but after a lot of use it can wear – so check that the teeth look perfectly symmetrical, and that they’re all there of course! The high power motors have a steel spur gear, which never wears at all.
Going beyond this stage requires heavy machinery, so if your motor needs more than this, send it back to us. While you’ve got the motor open, clean out the old grease and pack in plenty of fresh grease. The reassemble:
Put the gearbox cover back in place – it may just push back on, or you might need to GENTLY tap it back with a rubber mallet. Make sure that the gears are meshing properly before you hit it too hard. Refit the 5 cross-head screws – note that three of them (usually) have washers, whereas the two outside the centre ring do not. Now slide the motor back into the shell – you might need to turn it about a bit to get the gears to mesh. Refit the 6 cross-head screws and the 17mm nut. NOTE: do not use any power screwdriver or similar on these screws – the alloy is quite soft and strips easily. Just tighten them with a standard hand screwdriver.
Motor fitting tricks:
The Heinzmann motor is usually pretty easy to fit to any frame or fork, but sometimes you’ll have a pair of (usually suspension) forks which will not spread far enough. If this happens, try replacing the thin 17mm nut on the right side with a washer – the washer must still be on the INSIDE of the dropout when you fit the wheel to the fork. If you still need more room, do the same on the left side – but be aware that the protective disc will be loose when you take the wheel off if you do this.