Kingfish
100 MW
- Does your motorized wheel have a mind of its’ own and appear to wander while driving around a corner at times?
- Does it spin oddly with rumbly resistance?
- Does the motor create a grinding sound, particularly when cornering?
Could be that the problem is in the hub cover bearings. We can check the health and status of hub motors without disassembly by a couple of quick and easy tests. To begin – let’s be sure the following conditions do not apply as they will lead to distraction during diagnostics:
- Check Spoke Tension. Spokes should be tight and well-seated without any play or clicking.
- Wheel should be mounted firmly to the frame. Rear-suspension bikes should have fluid motion without any sort of rattle or deflection when cycled through movement.
- While the wheel is still mounted to the bike, elevate it so that it can rotate freely. A bike stand or fixture works best.
- Lightly spin the wheel with your hand.
Wobble Test:
This method is similar to how we test vehicle wheel bearings. Loose-fitting bearings are the most dangerous, and they lead to poor handling and grinding.
- Place your hands on the wheel at opposite sides of the perimeter.
- With modest effort, try to wobble the wheel back and forth, alternating left-pull/right-push with left-push/right-pull quickly.
Does the wheel wobble? Can you feel it or hear it clicking or does it feel like an indent as you go back and forth?
Lateral Test:
This one is more difficult and might take a second person to hole the frame steady. The bearings could be installed correctly but may have wear along the journal, or perhaps not entirely seated well.
- With both hands, instead of wobble, try shoving the wheel back and forth – alternating with left & right push, and left & right pull.
- Is there a clunking sound, an indentation, or clicking? Can you feel any movement or is it solid along the axle?
RWD + Rear-Suspension Test (not applicable to hardtails):
Sometimes there is still play in the setup that may be caused by other factors that can lead to poor handling, particularly with batteries mounted over the rear wheel on F/S bikes. If the wheel is firmly mounted, and the suspension appears solid, add static weight to the bike until it nears the level associated during normal operation. Then test the frame again for wobble and lateral motion perpendicular to the intended motion of suspension. Any significant movement or clicking in the framework should be investigated and corrected.
Replacing Bearings:
Unless you own a repair shop or have lots of experience replacing bearings, this is not a normal DIY task. Auto mechanics rarely have the equipment for this type of work, however a good machinist does - and in the process will inspect the mating surfaces for possible causes for failure if they exist. Normally bearings will wear out from exposure to water and debris. Inspect the seals for wear. If water is a problem consider venting the hub motor with a tiny weep hole or two near the perimeter of the cover.
Loose fitting bearings can cause other problems and may require hub cover repair or replacement. Axles typically fair better than covers though may also wear by improper fit. If the estimate of R&R is more than the hub motor, replace the motor.
Personally, I prefer to use top-quality Stainless-Steel Sealed Bearings having at least twice the maximum load-capacity and RPM of actual need. The differences in performance are plainly evident. :wink:
References:
RUST: DIY Hub Motor Repair & Restoration
Best of luck, KF
