Bosch failures?

[Old Mike]

I've had 1 Bosch Gen 3 motor that sounded dodgy from day one and was replaced under Warranty after 600 miles.

And I've got another Bosch Gen 3 motor on a different bike that is up to 8,500 miles and is sweet as a nut, sounds like new.

 

[maker]

It's not described in the user manuals. There is an obscure workshop note about how to properly install a seal on a Gen3 - I think because they originally shipped without this seal. But it makes for good instruction for properly sealing the motor:

1. Remove your drive side crank arm.
2. Remove the Bosch locking ring using the Bosch spider tool.
3. Slide all chaining, spacers, and guards off (noting the order!)
4. Carefully remove the black seal. I find tweezers or needle pliers work well.
5. Clean behind, pack with lots of grease, replace seal and refit everything.

If you want to replace the seal, it's this: Bosch Performance / Active / CX Main Bearing Seal
The lockring tool: Bosch Active / Performance Spider Tool

A bike shop told me that the original sealnt grease was water soluble, then Bosch spotted the specification flaw.

 

[SquireRides]

A bike shop told me that the original sealnt grease was water soluble, then Bosch spotted the specification flaw.

The last-gen Perf CX motors were shipping without a drive-side bearing seal for a while. It's only when i was pointed to a workshop advisor note about retro fitting the seal that I found out about removing, cleaning and re-greasing the seal.

I wonder if that could be the difference between your 600 and 8500 mile motors?

 

[Bearing Man]

Just for info guys: Gen 3 is a road bike motor. Everyone is calling the Gen 2 a Gen 3 and it's causing me much wasted time when trying to diagnose peoples problems (the two motors are very different inside) Gen 3 has a large chain wheel.

 

[RedTed]

I totally agree and I think one of the reason Bosch done away with the small chainring on the Gen 4 motors.
I have been doing a few tests with the MudStop and new seals too (see pdf attached) I wouldn't advise it, but I have been deliberately riding through water deeper than the motor and no ingress yet

Would you recommend fitting this upgrade whist motor is still covered by the manufacturers warranty, I take it if there was a problem it wouldn't invalidate it?

 

[Bearing Man]

Would you recommend fitting this upgrade whist motor is still covered by the manufacturers warranty, I take it if there was a problem it wouldn't invalidate it?

These parts are fitted exterior to the motor and will not invalidate the warranty. The MudStop has been evaluated by Bosch and agreed there would be no warranty issues.

 

[Maxb]

It's intresting how some people are getting more miles out there motors than others for me my first motor lasted 100 miles my second around 450 just having my third motor fitted. I am keen on my maintenance and regularly clean and 're grease the seal with Bosch grease I suspect it something to with the way I use the bike it's out in all conditions most rides are 25-30 miles and I like to pedal so I put a fare bit of force though the cranks I suspect this may not be helping

 

[maker]

It's intresting how some people are getting more miles out there motors than others for me my first motor lasted 100 miles my second around 450 just having my third motor fitted. I am keen on my maintenance and regularly clean and 're grease the seal with Bosch grease I suspect it something to with the way I use the bike it's out in all conditions most rides are 25-30 miles and I like to pedal so I put a fare bit of force though the cranks I suspect this may not be helping

I saw in another thread someone commented the fitter riders had more failures and they speculated that the fitter riders put more strain on the bearings through using less assistance. I am also on my third motor which has been used about as much as previous failures but still sounds good. I have been using in the dry so maybe wet is the big problem with Boch Gen 2.

 

[Bones]

3 motors are 1 battery in 2 years for me all under warranty.
As soon as it starts sounding like a coffee Grinder and impossible to pedal without power then it won't be long before the error codes appear.
BTW the mudstop seal will not fit on my set up due to the chain guide system fitted.

 

[Bearing Man]

It's intresting how some people are getting more miles out there motors than others for me my first motor lasted 100 miles my second around 450 just having my third motor fitted. I am keen on my maintenance and regularly clean and 're grease the seal with Bosch grease I suspect it something to with the way I use the bike it's out in all conditions most rides are 25-30 miles and I like to pedal so I put a fare bit of force though the cranks I suspect this may not be helping

This is because the amount of miles you get out of a motor normally has very little to do with the motor itself. 99.9% of the motors I repair have failed due to water or mud ingress. This can be through the crankshaft bearings or the main motor bearing. Mud build-up on the back of the drive sprocket will also be forced through the main motor bearing and no amount of seals or grease will stop this.
Failure mileage is almost completely dependant on:
A persons washing regime.
Whether the bike is washed upright or on its side.
Whether or not the bike is transported on a bike rack behind a car without motor covers.
Whether the hose sprinkler or the jet setting is used.
Whether the back of the sprocket is cleaned or inspected after a muddy ride.
Whether you own a Trek or Haibike (Collect lots of dirt and force it through main motor bearing because of some motor cover designs)
Whether you stop in deep mud like you would a normal bike or you just keep going because you can.
whether you ride a lot of deep water filled ruts or streams etc.

Now don't get me wrong, I am not saying anyone does this or not, I am just saying that these are the reasons why the bearings fail. Hard pedalling, jumping, rough terrain etc. I have never seen any of these affect the bearings. The bearings in the Bosch CX motor are at least twice the size of any other motor. They are enormous and totally over engineered for what they are doing.
I am not saying there is no problem here, the motor should be waterproof but it isn't, so if you're aware of some of the reasons for failure it may help your motor last a lot longer.
If you are riding through a lot of unavoidable water, fit the MudStop and right-hand crank seal, clean your sprocket if mud id building up and hopefully we will soon have a seal for the left.

 

[Bearing Man]

I saw in another thread someone commented the fitter riders had more failures and they speculated that the fitter riders put more strain on the bearings through using less assistance. I am also on my third motor which has been used about as much as previous failures but still sounds good. I have been using in the dry so maybe wet is the big problem with Boch Gen 2.

Misinformation sadly. Power is not the problem. I see no difference between a motor that has been used for 10,000 miles pushing a cargo bike around London with a guy with legs like tree trunks, to a commuter bike from Neatherlands, to a motor that has spent its entire life in turbo with dongle but comes from Spain. The bearings and gears are bullet proof, it is water ingress as you suspect.

 

[Bearing Man]

3 motors are 1 battery in 2 years for me all under warranty.
As soon as it starts sounding like a coffee Grinder and impossible to pedal without power then it won't be long before the error codes appear.
BTW the mudstop seal will not fit on my set up due to the chain guide system fitted.

If the grinding noise is ignored the bearing wears enough to lift the seals from the seats letting everything through to the motor, the enevitable fault codes are generally caused by water on the circuit board or as the freewheel gear eventually wears through the printed circuit board!
If you are out of warranty, ignoring the coffee grinder noise is the difference between a £15 bearing or a £600 motor!

 

[Bones]

Why worry about it when bosch do the 2 year rolling warranty on the motor. My mountain biking involves getting wet generally. Although I don't jet wash and clean around the drive chain it's inevitable that a motor that's only splashproof is going to screw the bearings up pretty fast in the UK conditions.

 

[Beekeeper]

This is because the amount of miles you get out of a motor normally has very little to do with the motor itself. 99.9% of the motors I repair have failed due to water or mud ingress. This can be through the crankshaft bearings or the main motor bearing. Mud build-up on the back of the drive sprocket will also be forced through the main motor bearing and no amount of seals or grease will stop this.
Failure mileage is almost completely dependant on:
A persons washing regime.
Whether the bike is washed upright or on its side.
Whether or not the bike is transported on a bike rack behind a car without motor covers.
Whether the hose sprinkler or the jet setting is used.
Whether the back of the sprocket is cleaned or inspected after a muddy ride.
Whether you own a Trek or Haibike (Collect lots of dirt and force it through main motor bearing because of some motor cover designs)
Whether you stop in deep mud like you would a normal bike or you just keep going because you can.
whether you ride a lot of deep water filled ruts or streams etc.

Now don't get me wrong, I am not saying anyone does this or not, I am just saying that these are the reasons why the bearings fail. Hard pedalling, jumping, rough terrain etc. I have never seen any of these affect the bearings. The bearings in the Bosch CX motor are at least twice the size of any other motor. They are enormous and totally over engineered for what they are doing.
I am not saying there is no problem here, the motor should be waterproof but it isn't, so if you're aware of some of the reasons for failure it may help your motor last a lot longer.
If you are riding through a lot of unavoidable water, fit the MudStop and right-hand crank seal, clean your sprocket if mud id building up and hopefully we will soon have a seal for the left.

a very informative, detailed and interesting post.

Thanks Bearing Man!

 

[Bearing Man]

Why worry about it when bosch do the 2 year rolling warranty on the motor. My mountain biking involves getting wet generally. Although I don't jet wash and clean around the drive chain it's inevitable that a motor that's only splashproof is going to screw the bearings up pretty fast in the UK conditions.

Good point but sadly, many are now out of warranty. BTW if your chain guide is one of the Miranda plastic ones, you may want to look at the design. These guides scrape the mud off the back of the sprocket and force it through the main motor bearing.

 

[Doomanic]

I binned the chain guide and replaced it with a simple nut. The motors lasted a lot longer after that.

Removed this;

And fitted this instead;

 

[Maxb]

I’m waiting for my 3rd motor it’s been at the shop for a month now waiting for a new motor it’s spent so much broken it will be getting sold when I get it back ,I need a mountain bike I can do mountain biking on I’m sure it will be a great bike for someone but it seems to be unsuitable for my needs.

Will consider if I am going to buy another emtb the new Bosch seems more reliable so could be tempted by an Whyte E 150

 

[Beekeeper]

I just can’t help noticing an uncanny link between posts of multiple motor failures and avitars of users showing bikes flying through the air / body armour / full face helmets ?

 

[Rob Rides EMTB]

Any reported failures of the 2020 Gen 4?

 

[Bearing Man]

Any reported failures of the 2020 Gen 4?

Not that I have heard of yet.

 

[Maxb]

I just can’t help noticing an uncanny link between posts of multiple motor failures and avitars of users showing bikes flying through the air / body armour / full face helmets ?

Is that not what everyone does on there mountain bikes ??

 

[Zimmerframe]

Any reported failures of the 2020 Gen 4?

Seen a couple pop past on here. This was one :

Bosch CX performance gen 4 dead

Got my Trek Rail about 3 months ago and completed almost 500km. Now the motor has committed suicide and giving me error code 500. Back at LBS waiting for an update. Curious if anyone else with a new gen4 motor had problems/failures similar to mine. Hoping this sort of “Brose experience” would...

www.emtbforums.com

 

[MrBrownstone]

Any reported failures of the 2020 Gen 4?

I know guys who have battery-motor connection issues. Motors shut off frequently when they hit bumps. Not sure if they have it sorted yet.

 

[Zimmerframe]

On my long running score sheet of forum reported motor failures (yes, I am that sad) , the Gen 4 Bosch has actually taken the lead over Brose in the last few weeks.

This is mainly from 504 failures - so most are seemingly rectified by a visit to the bike shop. The latest firmware is supposed to address this, however, there are still reported failures with the new firmware, so a work in progress.

A large chunk of manufactures jumped to Bosch with the Gen 4, so there's now numbers out there to start competing with Brose/Spesh circulation numbers. So we're going to see more mentions of failures.

 

[GrahamPaul]

On my long running score sheet of forum reported motor failures (yes, I am that sad) , the Gen 4 Bosch has actually taken the lead over Brose in the last few weeks.

This is mainly from 504 failures - so most are seemingly rectified by a visit to the bike shop. The latest firmware is supposed to address this, however, there are still reported failures with the new firmware, so a work in progress.

A large chunk of manufactures jumped to Bosch with the Gen 4, so there's now numbers out there to start competing with Brose/Spesh circulation numbers. So we're going to see more mentions of failures.

Are you including or excluding the 504 failures caused by tampering with (or bypassing) the speed limiter?

 

[Zimmerframe]

Are you including or excluding the 504 failures caused by tampering with (or bypassing) the speed limiter?

For Bosch, only tallying where people insist THEY HAVE NOT tampered, used a box, moved a magnet and say that it's totally stock. (There's a risk that some might lie, but I have no way of working out what % so I have to accept what is said).

For Brose, I tally everything as the question isn't asked enough to validly differentiate de-restricted or not and on the 1.2/1.3 it can be changed in the software, so people probably won't be honest about it... So unless someone says "I ran my Brose off the mains" or "I left it in the river overnight" - then it's logged as a fail, abused or otherwise.

 

[Doomanic]

I know guys who have battery-motor connection issues. Motors shut off frequently when they hit bumps. Not sure if they have it sorted yet.

I’ve had that. It’s the lower battery mount apparently and is a motor out job to rectify. LBS turned it around in a day (but didn’t update the DU firmware necessitating another visit today after the 504 error reared it’s ugly head ? )

 

[andy.blue.mini]

Afternoon all, I just joined the forums.

I collect my new Whyte E180 RS tomorrow and cannot wait to get out on it.

@ Brearing Man can I PM you, I have a specific question.

Cheers Andy

 

[Bearing Man]

Afternoon all, I just joined the forums.

I collect my new Whyte E180 RS tomorrow and cannot wait to get out on it.

@ Brearing Man can I PM you, I have a specific question.

Cheers Andy

Of course, no problem.

 

[Aitrui]

I still think Bosch gen2 is the most reliable, serviceable motor on the market. Mine getting it every day, rain, snow, mud, turbo mode most of the time, lot of mileage, my old bike same, no problems yet. I have 2 brand new spare motor ( cheap in local market), I bougth them, because why not, but I don't see the point to having them now, because these things wont die on their own.

Of course I maintain them, which means not pressure washing them, replacing the "seal",regreasing the drive side once in a while.

If one day, water will get inside, or bearing die, or the big white gear wear away, you can use Bearing Man kits to repair it which is still cheap, and repairable after warranty. That's why I didn't replaced my bike yet to different motor brand , because I think it's important to have stuffs, which can be economically repaired after the warranty expire.