540 Motor Washers

[Limerick91]

Really stupid question but i took apart my motor to get at the inside and the washers fell out, there was 3 of them, does anyone by chance know which order to put these back in or will it make a difference if they're put in differently?

Thanks.

[retroman]

OK, I'll try and explain! This is assuming that we are talking about a standard 540 type rebuildable motor

Against the commutator, you should have a larger fibre washer, that is slightly bigger than the comm. The next bit is a little bit of trial and error. The trick is to find where the armature balances in the magnetic field inside the can. Fit the fibre washer beside the commutator, that the brushes run on, then fit the armature back inside the can, and refit the endbell, but don't refit the brushes yet. If you push the armature axle from either the endbell end, or the can end, you will find that the armature will be pulled or pushed back by the magnets in the can. this is where the armature is balanced in the magnetic field. Then work out how many shims or washers are required for the armature to run in this position, without excessive end float.

Hope this makes sense. A lot of new motors I have had in the past haven't been correctly shimmed from the factory! So don't worry about all the washers falling out. If you have a good model shop near you that specialises in RC, they should keep packets of motor shims.

[Limerick91]

OK, I'll try and explain! This is assuming that we are talking about a standard 540 type rebuildable motor

Against the commutator, you should have a larger fibre washer, that is slightly bigger than the comm. The next bit is a little bit of trial and error. The trick is to find where the armature balances in the magnetic field inside the can. Fit the fibre washer beside the commutator, that the brushes run on, then fit the armature back inside the can, and refit the endbell, but don't refit the brushes yet. If you push the armature axle from either the endbell end, or the can end, you will find that the armature will be pulled or pushed back by the magnets in the can. this is where the armature is balanced in the magnetic field. Then work out how many shims or washers are required for the armature to run in this position, without excessive end float.

Hope this makes sense. A lot of new motors I have had in the past haven't been correctly shimmed from the factory! So don't worry about all the washers falling out. If you have a good model shop near you that specialises in RC, they should keep packets of motor shims.

Thank You!

I've rebuilt it, yet to test it but good to know it won't completely break if they're not in correct.

[94eg!]

The rotor doesn't always center itself at rest. It's best to spin the rotor while holding the motor so the rotor shaft is parallel to the ground. The spinning allows the rotor to overcome the forces of friction as the magnetic field forces the shaft along the bearing/bushing surface.

BTW: If your having trouble spinning the shaft by hand, install a pinion on the end. It will make it MUCH easier. Of coures you have to pop it off when you go to add shims...

Tuning Tip: If your shimming a stock motor w/ bushings, make sure the shim closest to the bushing is teflon instead of metal. Trinity sells these...