Mercedes/Smart Bionx powered bike w motor issues

[TenMile]

Hey all,

Just had a customer bring in a Mercedes/Smart into the shop they inherited from a family member (like this: https://electricbikereview.com/smart/ebike/). It's an absolutely beautiful bike.

Because the bike has not been used for several years, we ran the motor/battery through the Bionx diagnostic and everything passed just fine. The motor turns on and engages in every power level, however, makes a very loud grinding sound. If I turn the motor off, the bike doesn't grind and the wheel spins just fine. It makes this grinding sound at any power level, even in regen mode. I can't seem to find anything obvious. Any tips or suggestions appreciated. It appears that the Bionx hub is failing so I suppose the only fix is completely pulling the motor apart?

 

[E-HP]

The motor turns on and engages in every power level, however, makes a very loud grinding sound. If I turn the motor off, the bike doesn't grind and the wheel spins just fine. It makes this grinding sound at any power level, even in regen mode.

Reading the specs, it sounds like the hub is geared internally with 3 speeds. When you say every power level, do you mean in the three gears?

 

[99t4]

Thinking the OP means the BionX display controlled power assist (and regen) levels. 4 assist, 4 regen levels, plus a "neutral" (normal non-powered) mode.

TenMile, does the motor make the noise when set for power or regen, even when not moving?

That looks like the BionX G2 display. Should be able to bring up the diagnostic mode by holding the power on and mode buttons together for a few seconds and entering code 3772.

https://electricbikereview.com/forums/threads/accessing-diagnostic-mode-error-codelist-included.525/

EDIT: OK, I see you already did the diagnostic and it came up clean.

 

[E-HP]

Thinking the OP means the BionX display controlled power assist (and regen) levels. 4 assist, 4 regen levels, plus a "neutral" (normal non-powered) mode.

Then I'd ask does the same grinding noise happen when the bike shifts through the internal gears, or just in one or two of them.

If the problem is the transmission, and that's made by SRAM, then maybe there's a chance of getting parts?

 

[TenMile]

Hey all

It's not the IGH making the grinding sound. As mentioned, if the motor is switched off, the bike runs silently as normal. As soon as I switch the motor on (can even be in neutral) I hear a loud grinding sound. More pronounced when any of the power levels are selected. Makes the sound in both normal power and regen mode as well as no-power. When the motor is switched off, sound goes away.

 

[99t4]

OK, so it looks like we can rule out the IGH.

Thinking about this, but need better descriptions.

By "switch the motor on" do you mean when you power up the BionX system via the power on/off button on the display? Or is it when you push on the pedals to cause the torque sensor in the motor to call for assist?

Does the noise sound the same as long as the system is powered up, regardless of the assist/regen setting?

Regardless if the wheel is spinning or not? At various speeds?

Also, can you better describe the grind noise? My coffee grinder sounds different than when I try to shift my old stick shift truck into reverse too quickly. They both make a grinding sound.

 

[TenMile]

By "switch the motor on" do you mean when you power up the BionX system via the power on/off button on the display? Or is it when you push on the pedals to cause the torque sensor in the motor to call for assist?

When the motor is powered on via the display AND the wheel starts moving using the pedals. It only makes the grinding sound when the rear wheel is spinning and the motor is powered on. Happens in the stand and while riding (no difference). If you stop pedaling, but wheel is still spinning (but motor is still powered on), grinding sound continues.

Does the noise sound the same as long as the system is powered up, regardless of the assist/regen setting?

Yes, correct.

Regardless if the wheel is spinning or not? At various speeds?

ONLY if the wheel is spinning. Doesn't matter what speed.

Also, can you better describe the grind noise? My coffee grinder sounds different than when I try to shift my old stick shift truck into reverse too quickly. They both make a grinding sound.

Best way to describe it is that it sounds like a motorcycle engine. Not a Harley, lets say more like a Ducati, possibly an '80s vintage 4 cyclinder Yamaha