The Plettenberg Advance 30-10 is arguably one of the most popular direct drive F3A motors on the market. They are an inrunner configuration without a gearbox and are therefore very low maintenance.

About the only maintenance required is the occasional Bearing Change. The interval between Bearing changes will depend on a number of factors like the number of flights and the operating environment. Generally speaking, a Bearing Change after 500 flights is good insurance. If you operate in a hot or dusty environment more regular changes might be necessary.

 

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There is very little information (if any) about how to go about replacing the Plettenberg Advance bearings. This blog is an attempt to address this issue.

The original bearings are Japanese EZO brand. The type number engraved on the shield is: 6901Z and it’s dimensions are 24mm OD, 12mm ID and 6mm width. The bearings don’t have to be EZO but if choosing another brand make sure they are a known brand. In this case, the Customer provided NSK bearings.

Tools and materials required are quite basic:

  • Small Phillips jewellers screwdriver. Make sure it’s a good fit in the end bell screws. Last thing you want to do is burr the heads...
  • Hot air gun.
  • Locktite 648 retaining compound.
  • Locktit 243 blue thread lock compound.

Ok, firstly remove the prop bolt, washer and thrust washer. I’ve heard of people having trouble getting the thrust washer off the shaft taper. If you have this trouble try warming the washer up with a hot air gun. If that doesn’t work you may need a small puller to crack it off the shaft taper. In my case, the washer was easy to get off by hand. No pulling tools or warming up was required.

Next the end bell(for want of a better description) needs to be removed. The end bell is secured by five (5) M2 countersunk Screws. These screws are secured with thread locking compound so make sure your screwdriver is the right size so the screw doesn’t get damaged. Once all the screws are removed, a gentle push on the front of the shaft should release the end bell from the main housing. Carefully remove the end bell from the main housing and set aside. 

Alright, with the end bell removed the next thing to do is remove the rotor. Before doing this, remove the thin wave washer on the shaft and set aside with your M2 screws. A small tray is a good idea here otherwise you might find yourself on all fours scouring the floor looking for small parts! ;-) Next we remove the rotor. Take care here as the pull of the magnets and sharp edges of the fan can injur your fingers. You should be able  to push the front shaft down on the table whilst carefully pulling on the fan to remove the rotor completely. Set the rotor aside in a clean container that prevents Ferris material sticking to the magnets. If there are any Ferris particles stuck to the rotor magnets carefully clean them off.

We now have clear access to both the front and rear bearings. The rear bearing fell out of the end bell on this motor. The front one couldn’t be pushed out anywhere near as easy. This is where the heat gun comes into play... Simply warm up the front housing around the bearing. The alloy housing will expand a fraction and this is enough to enable the bearing to be gently pushed out with your finger.

Now that both bearings are out, clean the bearing seats in the housing. A paper towel with methylated spirits or IPA does the trick nicely. While you’re at it, clean the OD of each bearing too. Next apply a drop of Locktite 648 retaining compound to each bearing seat. It only needs to be applied to the bearing OD area. Using a cotton bud spread the compound around the bearing seat. You don’t need much of this stuff to do the job. The cotton bud will help soak up excess compound. Next carefully insert each bearing ensuring the bearings are pushed fully home. Wipe off any excess retaining compound and set things aside for 24 hrs. This allows the compound to cure. The purpose of the retaining compound is to ensure only the inner bearing rotates.

Twenty four (24) hours later, your bearings should be nicely retained. Assembly is the reverse of disassembly. Carefully insert the rotor back into the main housing and watch your fingers! You’ll need to ensure the front of the shaft lines up with the bearing ID. Gently push the rotor all the way home. Then refit the thin wave washer to the rear of the shaft. The end bell can then be refitted and pushed all the way home. Make sure the screw holes line up. Next fit the five (5) M2 Screws with some Locktite 243 thread lock compound. Don’t tighten the screws until all five (5) are screwed into the end bell.

To finish off, refit the thrust washer, prop washer and prop bolt.

Rotate the shaft by hand and all should be as smooth as silk. Job done!