Bosch planned obsolescence

[Anthony27]

The engine on my 2012 Moustache bike broke down, and it turned out the main cog wheel was ... broken in half. Because it's made of plastic. And you can't replace just the crappy cog, you have to change the whole engine.

I didn't expect this, although my dealer said I was lucky it lasted so long (8 years and about 6,000 miles). Well, well. Still cheaper to fix it than buying a new bike, but 800 francs (about £600) is a lot of money for a broken cogwheel, if you ask me.

I wonder if the later Bosch engines are made in the same way.

 

[flecc]

I'm afraid this is common practice with crank units in the industry. Panasonic started it when they produced the first of this type of crank unit in 2001, making it repair by replacement only with no internal spares available. Many others then followed suit.
.

 

[sjpt]

Is it a thing performnancelinebearings (https://www.performancelinebearings.com/) can fix, maybe for a mere £300 or so?

 

[Nev]

Does anyone know if it would be possible to use some special kind of glue to repair that plastic cog wheel? Or is it likely that a repair like that just wouldn't last very long?

 

[Amoto65]

How about using a 3d printer.

 

[Nealh]

Three options I see.
1. Performance line bearings.
2. 3D print a new one.
3. Have a new one laser cut or machined out of Aluminium or brass or option 1 may machine and fit a new part.

I know if it was my brothers bike he would machine a new part out at work.

 

[Fordulike]

Why on earth Bosch made that final drive cog out of plastic/nylon/cheese is beyond me.

Forum member's suggestions of 3D printing sounds like a great way to go.

 

[Ocsid]

Why on earth Bosch made that final drive cog out of plastic/nylon/cheese is beyond me.

Forum member's suggestions of 3D printing sounds like a great way to go.

The answer might be related to a lubricity issue and or noise? It has to be realised, metal on metal gearing has its own issues and brings its own complexities. Addressing these with a wet sump option would bring its own challenges.
From the picture the plastic has failed structurally, though, as a gearing solution, it appears to have done a good job. A composite plastic would help structurally, but probably compromise the gear wear etc?

It is nevertheless a poor show they don't make spares available, though I expect they regard an 8 year life as very acceptable in products for this market, even if we might not.

 

[Andy-Mat]

Why on earth Bosch made that final drive cog out of plastic/nylon/cheese is beyond me.

Forum member's suggestions of 3D printing sounds like a great way to go.

I do not have a clue as to whether Bosch still use Nylon/Plastic, but there were many problems of this type here in Germany, a few years ago with that gear, but it does seem to have gone quieter(Better?) more recently.
Maybe a gearwheel made from brass would hold out longer and be easier to produce, but the weight freaks will freak out!
One made from 3 D printing, IMO, would be even less likely to handle the stresses than the original.
If it must remain as Nylon/Plastic, then it needs a redesign, to make it stronger, possibly thicker.
Or maybe a metal outer gear ring, with a plastic middle part.....I say that as I have the impression from the excellent pictures that it started cracking from the outermost edge. But that is ONLY an impression.....not fact.
I had a quick look on pedelec Germany, and the Bosch motor gear problems seem to start around 2012, and are still there, as I am up to 2019 and some are busy making metal replacements for certain motor models, apparently:-

sonstige(s) - Alu Zahnrad für Bosch antrieb !!

@XploiD Wo denn? Ich bräuchte auch eins Ich hab Dir ne PN geschrieben.

www.pedelecforum.de

As I have never in my life (knowingly anyway) seen inside a Bosch motor, I cannot even guess if this is the same motor type as the OP has, sorry.
But it certainly looks impressive to me......
Or here:-

The posts stop in August 2020, with someone else with a broken gear, looking for a plastic or metal replacement.
So the problems are still happening in Germany, how sad for owners of such bikes.....
If I can answer or translate and any particular German emails, ask, but I am not translating everything! That would be unfriendly....
But maybe google can give anyone a hint or two.
I dislike Bosch products here in Germany, and their poor service history and luckily have never bought any.....But it appears to me that people are making such parts here, and with reasonable success.
Of course there are also posts in the topic, from complete idiots who are worrying (already!) about the possible weight increase.......and they had not actually bought the part!! But there are idiots everywhere on this planet!
Regards to all and if you need questions answered about these parts, try me, though a better idea is maybe a Skype connection and then I can answer any questions far more easily. Written translations are simply hard work....
Andy

 

[Fordulike]

If it is simply a case that the spare parts are not available and Bosch aren't willing to release the blueprints for them, then I say shame on them.

I can understand that Bosch would prefer owners not to be tinkering with their motors during the warranty period, but what about when that runs out

Whilst Bafang mid drives might not have the same prestige as Bosch, they are pretty easy to work on and virtually any spare part can be bought online.

Also, the BBS series have a fully metal final drive cog and with the right grease on the cogs, has proven to be quiet and reliable over thousands of miles.

As much as I love Bosch products and swear by their car batteries for every car I've owned, I must say they aren't convincing me to buy one of their electric bikes quite yet

 

[Nealh]

I do not have a clue as to whether Bosch still use Nylon/Plastic, but there were many problems of this type here in Germany, a few years ago with that gear, but it does seem to have gone quieter(Better?) more recently.
Maybe a gearwheel made from brass would hold out longer and be easier to produce, but the weight freaks will freak out!
One made from 3 D printing, IMO, would be even less likely to handle the stresses than the original.
If it must remain as Nylon/Plastic, then it needs a redesign, to make it stronger, possibly thicker.
Or maybe a metal outer gear ring, with a plastic middle part.....I say that as I have the impression from the excellent pictures that it started cracking from the outermost edge. But that is ONLY an impression.....not fact.
I had a quick look on pedelec Germany, and the Bosch motor gear problems seem to start around 2012, and are still there, as I am up to 2019 and some are busy making metal replacements for certain motor models, apparently:-

sonstige(s) - Alu Zahnrad für Bosch antrieb !!

@XploiD Wo denn? Ich bräuchte auch eins Ich hab Dir ne PN geschrieben.

www.pedelecforum.de

As I have never in my life (knowingly anyway) seen inside a Bosch motor, I cannot even guess if this is the same motor type as the OP has, sorry.View attachment 39580
But it certainly looks impressive to me......
Or here:-
View attachment 39581
The posts stop in August 2020, with someone else with a broken gear, looking for a plastic or metal replacement.
So the problems are still happening in Germany, how sad for owners of such bikes.....
If I can answer or translate and any particular German emails, ask, but I am not translating everything! That would be unfriendly....
But maybe google can give anyone a hint or two.
I dislike Bosch products here in Germany, and their poor service history and luckily have never bought any.....But it appears to me that people are making such parts here, and with reasonable success.
Of course there are also posts in the topic, from complete idiots who are worrying (already!) about the possible weight increase.......and they had not actually bought the part!! But there are idiots everywhere on this planet!
Regards to all and if you need questions answered about these parts, try me, though a better idea is maybe a Skype connection and then I can answer any questions far more easily. Written translations are simply hard work....
Andy

Looking at both pics, they appear to be the same design. The latter re-engineered post production mod is the way forward.
The tdsz2 had a similar issue with the Blue nylon drive gear failing, the answer was a replacement oem one in brass.

 

[Michael Price]

I read somewhere that they use plastic cogs for noise reasons more than anything else

I would worry about replacing anything plastic with a metal copy - you could create wear related issues with other parts in the motor????

 

[Andy-Mat]

Looking at both pics, they appear to be the same design. The latter re-engineered post production mod is the way forward.
The tdsz2 had a similar issue with the Blue nylon drive gear failing, the answer was a replacement oem one in brass.

A good choice if I may say so, as Brass tends to need less oil and grease than say steel or aluminium, as it is partially what engineers call "self lubricating", and a thin coat of a good quality product usually surfices, assuming that the possible wear surfaces are generous. Though that is not always possible to achieve when "simulating" an old design, as here.
Sintered bronze is another possible alternative that is self lubing, as oil is trapped in the particles, when manufactured, buy huge pressures.
Though I cannot offer an accurate opinion with regard to physical strength, say in comparison to the plastic/Nylon original gearwheel....
Regards
Andy

 

[Andy-Mat]

I read somewhere that they use plastic cogs for noise reasons more than anything else

I would worry about replacing anything plastic with a metal copy - you could create wear related issues with other parts in the motor????

According to the German Pedelec web site, that was a worry, but the gears made and tested have not proven to be noisy in use, but they had only done some 500 Kms (if I remember correctly), when this was talked about.
Its a good start at any rate!
regards
Andy