Why Bosch Motors should not be under swung on eMTB's..

[Martin@e-bikeshop]

Hi Guys,

Just come to fix the famous knocking noise / grinding on a Bosch motor this morning.
I am used to working on nice clean motor internals with the inverted mounted Bosch drives.

Couldn't believe what I found when I opened this one up..



I understand for town / commuter / trekking bikes the under swung motor doesn't matter too much about being so close to the tarmac, but I think on off-road machines it is asking for trouble.

The pictures are of the inside of the motor cover, but some of this had made its way into the actual motor gearing. It was a bit of a mess in there with dirt and grit. Makes me wonder how the motor could wear far more quickly in such conditions.

The purpose of this post it not to slate under swung motors in anyway - BUT to make people aware that if you are using an under swung motor for mountain biking, its probably worth having the motor cleaned out regularly to avoid any decay of the motor and therefore ensure a good long term e-MTB'ng experience.

Regards
Martin

 

[flecc]

I have to say that's lousy design by Bosch if the crankcase is so leaky that road muck can enter it. One can open up an underslung 10 year old Panasonic unit and it will always be pristine, just as it was when first manufactured, thanks to the very effective sealing. Indeed, in December 2007 I rode an Agattu through deep water with it's Panasonic unit fully submerged without any ill effect.

 

[103Alex1]

I've always had severe reservations about buying Bosch. Have to say seeing that's not done much to persuade me I was wrong !

 

[Martin@e-bikeshop]

I've always had severe reservations about buying Bosch. Have to say seeing that's not done much to persuade me I was wrong !

Most of this was in the motor housing as opposed to in the actual motor gearing. Although there was some mud/grit actually in there.

It all buckles down to the inverted motor. Its above the frame so much more resistant to knocks / being splattered constantly with mud and water. In fact whenever I take the inverted motors apart the most I muck I get out of them is just a smear of worn grease on a tissue. Certainly no mud or grit.

Regards
Martin

 

[shemozzle999]

Just a case of finding a suitable rectangular plastic bottle, milk maybe, that can be fashioned into a splash guard.
Spray it black to blend it into the background.

Although the clacking and banging isn't only restricted to the under slung models.

http://www.youtube.com/watch?v=hFj-q0lI8bI

 

[Zebb]

I dont think that its that bad, I would say its just a bit dusty at worst.

 

[Artstu]

[video=youtube;Q_tFgwRdUfw]http://www.youtube.com/watch?v=Q_tFgwRdUfw[/video]

 

[flecc]

I can appreciate that the overslung motor is less vulnerable, indeed I think it looks better too, but by design there should be no chance of road dirt getting into the gears casing. I also wonder why these units are being opened already, considering how new this design is. I'd have thought they'd have adopted the "sealed for life policy" that Panasonic have.

 

[Martin@e-bikeshop]

I can appreciate that the overslung motor is less vulnerable, indeed I think it looks better too, but by design there should be no chance of road dirt getting into the gears casing. I also wonder why these units are being opened already, considering how new this design is. I'd have thought they'd have adopted the "sealed for life policy" that Panasonic have.

Hi Flecc,

The units are begin opened on occasion as some models have created a clicking noise under pressure. This is because the grease initially installed on the floating bearing is being dispersed on some users models. Therefore the clicking is the floating bearing moving and making a metal on metal noise where the grease is no longer.

When the case is opened up and a slightly thicker layer of grease from new is applied the problem is resolved. The noise doesn't damage the motor in any way, it can just be irritating. Fortunately people like my self have the resolution and they are now fixed.

As fro the motor case itself its pretty darn well sealed. Most of the muck in the picture had accumulated in the plastic motor housing guard that overs the external cables. Normally little dirt gets in here although on this particular model KTM have cut away holes in the housing to allow the battery cable etc to pass through. This is where the muck gets in. Unfortunately because of the position it is right in the firing line of all the muck a trail might throw at the bike.

I found a little dirt in the actual engine casing which should not have been there. Although on this one the muck had built up so bad it was being pushed firmly against the casing. This along with the floating bearing / seal not being correctly greased had allowed a little ingress.

I have to say I never get any dirt in either the casing nor the motor in the inverted position as it is tucked out the way.

I do agree the Panasonic are very well sealed indeed.
Proved by your example of submerging it and it was fine.

Regards
Martin

 

[Martin@e-bikeshop]

Although the clacking and banging isn't only restricted to the under slung models.

Bosch eBike Electric Motor - Problem with banging / clacking / noises on the electric motor drive - YouTube

Yep true true, although this post is not about the noises its about the dirt build up.
Anyhow Shemozzle - you could have at least used my own video for demonstration -

[video=youtube;rElq4W7BHJY]http://www.youtube.com/watch?v=rElq4W7BHJY[/video]

Regards
Martin

 

[shemozzle999]

Hi Flecc,

The units are begin opened on occasion as some models have created a clicking noise under pressure. This is because the grease initially installed on the floating bearing is being dispersed on some users models. Therefore the clicking is the floating bearing moving and making a metal on metal noise where the grease is no longer.

When the case is opened up and a slightly thicker layer of grease from new is applied the problem is resolved. The noise doesn't damage the motor in any way, it can just be irritating. Fortunately people like my self have the resolution and they are now fixed.

As fro the motor case itself its pretty darn well sealed. Most of the muck in the picture had accumulated in the plastic motor housing guard that overs the external cables. Normally little dirt gets in here although on this particular model KTM have cut away holes in the housing to allow the battery cable etc to pass through. This is where the muck gets in. Unfortunately because of the position it is right in the firing line of all the muck a trail might throw at the bike.

I found a little dirt in the actual engine casing which should not have been there. Although on this one the muck had built up so bad it was being pushed firmly against the casing. This along with the floating bearing / seal not being correctly greased had allowed a little ingress.

I have to say I never get any dirt in either the casing nor the motor in the inverted position as it is tucked out the way.

I do agree the Panasonic are very well sealed indeed.
Proved by your example of submerging it and it was fine.

Regards
Martin

Grease problem on 45 unit:

Bosch Pedelec Motor DU45 zerlegt, Hauptwelle erneuert, Inside- view - YouTube

 

[flecc]

Understood Martin. It seems that KTM cable entry point needs to be properly sealed with a dedicated grommet and Bosch be a bit more generous with the grease. The Panasonic units with either all steel or part nylon gear trains never need greasing, even after 10 years of use, so that could be the same for the Bosch unit.

However, looking at the video shows that Bosch have not compartmentalised the gears away from the electronics in the way Panasonic have done, so the grease can get where it's not wanted and potentially cause other problems if too copious.
.

 

[Morrison]

Damn it! I've never posted before however I've been reading this forum trying to determine which bike to go for. The bike I've chosen is the ktm macina race but this has a underslung bosch motor and I would be doing a lot of muddy trails because the weather is not always like this. In the back of mind I was thinking the motor was in a vulnerable area so now I'm back to the drawing board.

 

[flecc]

Damn it! I've never posted before however I've been reading this forum trying to determine which bike to go for. The bike I've chosen is the ktm macina race but this has a underslung bosch motor and I would be doing a lot of muddy trails because the weather is not always like this. In the back of mind I was thinking the motor was in a vulnerable area so now I'm back to the drawing board.

As Shemozzle posted above, you could stay with your choice by providing a simple deflector shield, something often done for other vulnerable crank units like the Cyclone motors.

 

[Hugh]

Damn it! I've never posted before however I've been reading this forum trying to determine which bike to go for. The bike I've chosen is the ktm macina race but this has a underslung bosch motor and I would be doing a lot of muddy trails because the weather is not always like this. In the back of mind I was thinking the motor was in a vulnerable area so now I'm back to the drawing board.

Haibike's the answer to that, subject to affordability of course.

 

[Kudoscycles]

Damn it! I've never posted before however I've been reading this forum trying to determine which bike to go for. The bike I've chosen is the ktm macina race but this has a underslung bosch motor and I would be doing a lot of muddy trails because the weather is not always like this. In the back of mind I was thinking the motor was in a vulnerable area so now I'm back to the drawing board.

Morrison....if at this price level I would look at the Haibike XDruro or the latest Panasonic KTM e-race hub drive,the former because of the Bosch motor in the inverted mode (more ground clearance) and the latter because it has low speed grunt.
KudosDave