Bosch Gen 2 friction

[Beekeeper]

Noticed a difference between two Bosch Gen 2 motors with the chain off. Spinning the cranks backwards both appear fine, very little friction so I’m assuming main drive bearing fine on both bikes. However when spinning the other way there is a noticeable difference between the two motors. One spins with very little friction while the other seems heavy and sluggish and I can only get one complete revolution when spinning and letting go of the crank. Any ideas @Bearing Man?

 

[Bearing Man]

Noticed a difference between two Bosch Gen 2 motors with the chain off. Spinning the cranks backwards both appear fine, very little friction so I’m assuming main drive bearing fine on both bikes. However when spinning the other way there is a noticeable difference between the two motors. One spins with very little friction while the other seems heavy and sluggish and I can only get one complete revolution when spinning and letting go of the crank. Any ideas @Bearing Man?

This can be due to a few things on the Gen 2. If any extra sealing options have been fitted, these will add friction. Earlier Bosch motors main motor bearings ran with less friction than the latest ones with better sealing. The main motor bearing shield was updated to incorporate a rubber lip which also adds slight friction.
Then there is the silly felt washer, if that is fitted in one and not the other, that will make a difference.
How many miles they have covered will make a difference.
Bearing condition etc. etc.

 

[Beekeeper]

This can be due to a few things on the Gen 2. If any extra sealing options have been fitted, these will add friction. Earlier Bosch motors main motor bearings ran with less friction than the latest ones with better sealing. The main motor bearing shield was updated to incorporate a rubber lip which also adds slight friction.
Then there is the silly felt washer, if that is fitted in one and not the other, that will make a difference.
How many miles they have covered will make a difference.
Bearing condition etc. etc.

Thanks Bearing Man. I have to admit I’m guilty of using the silly felt washers. Trouble is I think they look rather cool and ordered about 20 years supply of them together with enough green tacky grease to fill an olympic swimming pool. It could well be a contributing factor to the friction although both bikes have them fitted. The range of both bikes is similar so perhaps not a major issue. Mileage is around 3500 for each motor. We don’t use them in muddy or wet conditions only the roads and fire tracks.

 

[Bearing Man]

Thanks Bearing Man. I have to admit I’m guilty of using the silly felt washers. Trouble is I think they look rather cool and ordered about 20 years supply of them together with enough green tacky grease to fill an olympic swimming pool. It could well be a contributing factor to the friction although both bikes have them fitted. The range of both bikes is similar so perhaps not a major issue. Mileage is around 3500 for each motor. We don’t use them in muddy or wet conditions only the roads and fire tracks.

Are both motors the same age?
Take a look here too if you get a minute: https://www.facebook.com/EbikeMotorCentre/posts

 

[Beekeeper]

Are both motors the same age?
Take a look here too if you get a minute: https://www.facebook.com/EbikeMotorCentre/posts

Thanks Pete, yes both motors are same age and same mileage. useful article, thanks. I was aware that the felt seals are not a great idea especially under certain riding conditions. I replace them yearly and coat them in tacky grease first around the circumference and behind them. We mainly ride on roads in the dry and all looks pretty clean when I remove and replace them each year. I’ll have a good inspection next time to see if there is any wear on the shaft.