Alternative Grease for servicing the CX seal.

[Beekeeper]

I use a metal hook to rake out the twigs and dirt, then blow it clean with compressed air. But that's only because I have a compressor. But you're right, a brush and sprinkled water is the best you can normally do. If the seal is in place and greased you should be fine.
Also remember, Just because the cheap seals that don't really work that well came free with your grease...you don't have to use them

I’ve always wanted to know why that large silver cylinder on the drive side of the Bosch is never lubricated. In your videos you advise not to even put finger prints on it. Surely without even the thinnest of lubes wouldn’t it suffer from a metal on metal situation? What would happen if you did put a thin lube on it just out of interest?

 

[Bearing Man]

I’ve always wanted to know why that large silver cylinder on the drive side of the Bosch is never lubricated. In your videos you advise not to even put finger prints on it. Surely without even the thinnest of lubes wouldn’t it suffer from a metal on metal situation? What would happen if you did put a thin lube on it just out of interest?

That part is the freewheel gear and it fits into the large clutch bearing. You can put your fingers on it but any grit or dirt what so ever could badly damage the bearing surface, hence, best not to touch it.
A clutch bearing needs to grip the bearing surface it runs on when it needs to lock the drive. If a high pressure or Teflon grease it may slip or judder (both scenarios are bad). If an abrasive grease like Graphite or Moly grease is used it may also slip and may contaminate plastic gearing.
There is normally always enough grease left in the bearing to "go again". If not? then a suitable grease like the one we use should be applied.

 

[Beekeeper]

That part is the freewheel gear and it fits into the large clutch bearing. You can put your fingers on it but any grit or dirt what so ever could badly damage the bearing surface, hence, best not to touch it.
A clutch bearing needs to grip the bearing surface it runs on when it needs to lock the drive. If a high pressure or Teflon grease it may slip or judder (both scenarios are bad). If an abrasive grease like Graphite or Moly grease is used it may also slip and may contaminate plastic gearing.
There is normally always enough grease left in the bearing to "go again". If not? then a suitable grease like the one we use should be applied.

Thanks, I’ve just looked up what clutch bearings are and how they work. They seems to have lots of tiny springs which facilitate the grabbing effect when the shaft tries to rotate in the reverse direction. Clever stuff!

 

[Beekeeper]

So is this clutch bearing what you refer to as the “main motor bearing” and the one in the direct firing line of water and mud ingress?

 

[Bearing Man]

So is this clutch bearing what you refer to as the “main motor bearing” and the one in the direct firing line of water and mud ingress?

No, the main motor bearing is the relatively large bearing that supports the aluminium sprocket carrier and the large plastic drive gear behind the cover. The clutch bearing can be affected when water gets through the right-hand crankshaft bearing.
The blue bearing in the case below is the main motor bearing and the rusty thing in the white drive gear is the clutch bearing. The gear below that is the freewheel gear after water has entered the motor.

 

[Beekeeper]

Great pics. Thanks ??

 

[calvintys]

Mobil Polyrex™ EM Series
Electric Motor Bearing Grease

Product Description
Super-premium Mobil Polyrex™ EM Series greases are specially formulated for electric-motor bearings. The advanced thickener formulation and proprietary manufacturing techniques provide improved bearing performance and protection for long electric motor life.

Applications
Mobil Polyrex EM greases are recommended by many major bearing and electric motor manufacturers for long-life lubrication of electric motor ball and roller bearings.

Mobil Polyrex EM 103 is more specifically recommended for applications such as vertically mounted bearings, or very large motors where a stiffer grease consistency may be required by the OEM.

Mobil Polyrex EM greases have been shown to be compatible with a number of ExxonMobil lithium complex greases, as well as competitive electric motor mineral polyurea products, as determined by the methodology of ASTM D6185. For specific questions about grease compatibility, contact your Mobil representative.

Key applications include:
• Electric motor bearings
• Fin fan bearings
• High-temperature pump bearings
• Factory-filled, sealed-for-life ball bearings
• Ball or roller bearings operating at high temperatures where low oil separation is required
• Mobil Polyrex EM for ball or roller bearings operating in noise sensitive environments

 

[Bearing Man]

Please think carefully before putting a different grease in or on your motor.

Many greases might look good for electric motors, but an ebike motor is not technically an electric motor! It has an electric motor inside it, but the thing itself is mostly gears and electronics. This is when a much deeper dive is required before using a different grease.
It should be asked if the grease is compatible with plastic gearing?
Is it dielectric to protect the open electronics on the PCB?
Is it compatible with clutch bearings, high pressure or high performance Teflon, ceramic etc. greases causes many problems.
is it compatible with the standard bearing or gear grease? Aluminium based greases, like a marine grease, can turn lithium based greases back to oil for example.
Is it compatible with NBR O-rings and seals?
Etc, etc.

We spend a lot of our time, cleaning out different greases from motors, where people have bought the best grease money can buy believing it's the best thing that can be used... but if it's not the right grease for the job, you may end up paying the ultimate price!

 

[RustyMTB]

As a greasing nerd, cleaning & regreasing regularly with the Bosch tacky stuff, I do find the grease degrades quite quickly, discolouring & thinning out noticeably. I've wondered why & the only thing I can think of is heat from either the motor or friction from spinning the cranks but that seems a flimsy theory.