Bosch Gen4 Seal Service & Grease up

[RustyMTB]

I would love for this to be a simple home fix for people, but to fit this part to the Gen 4 motor does require a full strip down because the crankshaft must be removed and this cannot be done until the PCB, transfer gears and electric motor have been removed. This would probably be ok for a few, but it would be a nightmare for many.

*Cracks knuckles*

 

[Bearing Man]

Appreciate the effort . Hopefully this solution is successful and can be applied to other motors as well.
Just a few questions regarding the Bosch Gen4 CX bearing seals??:

-Would this replace the current bearing seal kit available from Bosch or would it be an additional component (if you know what I mean).

-Are you developing a better crank shaft bearing that would prevent water ingress?

I understand if you’re not able to provide details (patent reasons), but I look forward to any improvements for the water ingress issue on this motor. These motors are getting better each year and you’re probably seeing issues that the engineers overlooked or never expected.

On a side note; I’m probably the “poster-boy” for motor abuse, but I’ve been lucky for the past 4 years. I try to service what I can but it’s difficult to avoid the daily washing, occasional submerging, types of weather, etc, but I make a conscious effort to maintain correct cadence and not “clunk” the crank. Not sure what else I can do?

Anyways, I’m glad you have a “rescue-room” along with possible solutions.

No, the Bosch bearing shields are working quite well. Unfortunately this is not where the water is coming in. The water is traveling between the crankshaft and the freewheel sleeve (the thing the front chainring is attached to). Once water gets in here, it rusts the crankshaft which quickly wears the plastic crankshaft bushes, this lifts the seal further off its seat allowing more water into the motor. This is why the crankshaft in my earlier pictures looks like it does. And this is what we have stopped happening.

 

[RustyMTB]

On that basis, Pete, do you think there is any mileage in running a bead of some kind of sealant between the crank & the freewheel sleeve as a temprary lash up or is that a monumentally stupid idea?

...I do realise I'm asking a guy who makes a living fixing motors for tips on how to avoid having to have a motor fixed

 

[Bearing Man]

If you flick that white plastic washer out the way, pack a bit of green grease behind it and refit, it may help a bit. Don't get any grit in their though.

 

[RustyMTB]

Just ran out & did that. The white seal is very loose behind its circlip & with the pedal reinstalled, you can see just how much of a vulnerability that is in there.

 

[Stihldog]

If you flick that white plastic washer out the way, pack a bit of green grease behind it and refit, it may help a bit. Don't get any grit in their though.

That’s a really good tip . Easy to do when/if you install the bearing seal shield kit and green grease. (Mmm…green grease )

 

[Tony4wd]

Did one of our bikes today, already some dirt behind the very loose plastic washer. I cleaned it out with a Q-tip and pick. The plastic seal behind the washer looks in good shape so hopefully not much contamination has occurred.

 

[Hattori-Hanzo]

Was fitting some new cranks today, so thought I'd apply some fresh grease behind the seals, could I get the nds seal off, nope....!

I've used circlip pliers in the past, like how Rusty shows in his vid, but the seal was having none of it today, just wouldn't budget.

Anyone have any other techniques for getting it off? I don't have a plectrum to hand

 

[RustyMTB]

They do get strong suction vibes. I use a pair of pliers against the inner face of the steel part of the seal & wiggle it back & forth until the seal frees off. It's a feel thing but with patience, the seal will break free & come away. The plectrum is iffy ime, can easily break the seal.

 

[Tony4wd]

Was fitting some new cranks today, so thought I'd apply some fresh grease behind the seals, could I get the nds seal off, nope....!

I've used circlip pliers in the past, like how Rusty shows in his vid, but the seal was having none of it today, just wouldn't budget.

Anyone have any other techniques for getting it off? I don't have a plectrum to hand

You'll need to get a plectrum and gently tease the edges of the seal up; if you're careful you shouldn't break the seal.

 

[JGH]

Can someone please advice me if the motor in the guide for seal replacement is the same as mine (Bosch Performance CX Gen 4 (2020? bike itself is 2022 model)) and if the same seal set is necessary? It looks slightly different and after removal of the bottom cover bare wire connectors are visible (lights, speed sensor wires etc).

Thanks in advance.

EDIT: Looks like mine is Bosch Performance CX Gen4 CRUISE version. Still, is the procedure and the kit same to extend the life of the motor?

The below image is not exactly from this model but the exposed wires look very similar in my motor.

 

[Stihldog]

Can someone please advice me if the motor in the guide for seal replacement is the same as mine (Bosch Performance CX Gen 4 (2020? bike itself is 2022 model)) and if the same seal set is necessary? It looks slightly different and after removal of the bottom cover bare wire connectors are visible (lights, speed sensor wires etc).

Thanks in advance.

EDIT: Looks like mine is Bosch Performance CX Gen4 CRUISE version. Still, is the procedure and the kit same to extend the life of the motor?

View attachment 143379
View attachment 143375
The below image is not exactly from this model but the exposed wires look very similar in my motor.
View attachment 143383

I’ve got the 2020 Trek Rail, Bosch gen4 motor. Looks the same as yours but your motor alignment seems a little different.

Anyways, I keep 2 Bosch seal kits and try to install one at least once a year.

When you’ve installed them once …the second time is easy. Use the search for tips and tricks on the installation. It helped me.

 

[Bones]

Can someone please advice me if the motor in the guide for seal replacement is the same as mine (Bosch Performance CX Gen 4 (2020? bike itself is 2022 model)) and if the same seal set is necessary? It looks slightly different and after removal of the bottom cover bare wire connectors are visible (lights, speed sensor wires etc).

Thanks in advance.

EDIT: Looks like mine is Bosch Performance CX Gen4 CRUISE version. Still, is the procedure and the kit same to extend the life of the motor?

View attachment 143379
View attachment 143375
The below image is not exactly from this model but the exposed wires look very similar in my motor.
View attachment 143383

It will be the same casing on the Gen 4 so the seal kit will fit.
It's just that yours is mounted more vertical than most others that are horizontal mounted.

 

[Spiff]

Hi Bearing Man, I have been reading your clear explanations of the motor failing mechanism of water ingress between the crankshaft and the freewheel sleeve, and the packing of green grease behind the white plastic washer to avoid the water ingress. But in your new Crankshaft Upgrade kit there is a big improvement over the white plastic washer, which is the newest Single Lip Rotary Seal with lip facing outwards, so I got a couple of questions:

• Is it possible to remove the white plastic washer, and insert the newest Single Lip Rotary Seal (and may be the bronze bushing) in its place and without further tear down of the motor?
• Would ebike Motor Centre be selling this Single Lip Rotary Seal.

If the answer to both questions is YES, this would be a very easy DIY preventive maintenance that would avoid the termination of many motors, although I suppose you'd prefer to sell a complete Upgrade kit, but there are enough Bosch motors out there for DIY preventive maintenance, Complete Upgrade or Overhaul and many other tasks that you can provide.

Bosch Gen 4 Upgrade Service - eBike Motor Centre (Performance Line Bearings)

At eBike Motor Centre we noticed a failure pattern on the Bosch Generation 4 motors when used on EMTB’s. We could also see from our own experience, and the sheer number of Bosch Gen 4 motors going through our workshop, there were a few issues that needed addressing, particularly when used...

www.ebikemotorcentre.com

 

[Bearing Man]

Hi Bearing Man, I have been reading your clear explanations of the motor failing mechanism of water ingress between the crankshaft and the freewheel sleeve, and the packing of green grease behind the white plastic washer to avoid the water ingress. But in your new Crankshaft Upgrade kit there is a big improvement over the white plastic washer, which is the newest Single Lip Rotary Seal with lip facing outwards, so I got a couple of questions:

• Is it possible to remove the white plastic washer, and insert the newest Single Lip Rotary Seal (and may be the bronze bushing) in its place and without further tear down of the motor?
• Would ebike Motor Centre be selling this Single Lip Rotary Seal.

If the answer to both questions is YES, this would be a very easy DIY preventive maintenance that would avoid the termination of many motors, although I suppose you'd prefer to sell a complete Upgrade kit, but there are enough Bosch motors out there for DIY preventive maintenance, Complete Upgrade or Overhaul and many other tasks that you can provide.

Bosch Gen 4 Upgrade Service - eBike Motor Centre (Performance Line Bearings)

At eBike Motor Centre we noticed a failure pattern on the Bosch Generation 4 motors when used on EMTB’s. We could also see from our own experience, and the sheer number of Bosch Gen 4 motors going through our workshop, there were a few issues that needed addressing, particularly when used...

www.ebikemotorcentre.com

View attachment 144874 View attachment 144875

Sadly, it's not possible to fit all this in situ because the seal situated behind the plastic washer has a steel band that tends to be bonded on the early motors, and corrodes on the later motors. Getting this part out, and cleaning it up to receive the new parts, would not be possible. Also in most cases the plastic bushes will be totally shot!

 

[Spiff]

What a pity!!!

But will you sell the crankshaft ungrade kit, only parts. Because sending a used motor from Europe to UK, is a complex and expensive task

 

[Bearing Man]

What a pity!!!

But will you sell the crankshaft ungrade kit, only parts. Because sending a used motor from Europe to UK, is a complex and expensive task

Because the Gen 4 is really not a DIY type of motor, many people would be in for a real shock if they thought they would give this a go. There are so many issues when working on this motor, but our main concern is the plastic bushes have the consistency of an egg shell, and are a pain to fit without breaking them.

We will be selling this kit to all our partners and supplying them with the relevant training. So, there should be someone in the EU who can help.

 

[Spiff]

Because the Gen 4 is really not a DIY type of motor, many people would be in for a real shock if they thought they would give this a go. There are so many issues when working on this motor, but our main concern is the plastic bushes have the consistency of an egg shell, and are a pain to fit without breaking them.

We will be selling this kit to all our partners and supplying them with the relevant training. So, there should be someone in the EU who can help.

Thank you for the answer.

I live in the Mediterranean Coast where we have a dry climate, and my Bosch powered bike still has 2 years 3 months warranty left and I wash my bike with a wet spounge, so it is not likely that my motor will have water ingress between the crankshaft and the freewheel sleeve. But anyway, if there is a cheap DIY fix, like the new seal and bronze bushing, I'd install it as preventive maintenance. In my previous bike, I opened my Shimano E8000 motors several times to re-grease them and I did not have any issue.

But I can not justify to myself sending a working motor to an unknown workshop (not you, of course) and spend 250 - 300€ for a preventive maintenance.

 

[Bearing Man]

Thank you for the answer.

I live in the Mediterranean Coast where we have a dry climate, and my Bosch powered bike still has 2 years 3 months warranty left and I wash my bike with a wet spounge, so it is not likely that my motor will have water ingress between the crankshaft and the freewheel sleeve. But anyway, if there is a cheap DIY fix, like the new seal and bronze bushing, I'd install it as preventive maintenance. In my previous bike, I opened my Shimano E8000 motors several times to re-grease them and I did not have any issue.

But I can not justify to myself sending a working motor to an unknown workshop (not you, of course) and spend 250 - 300€ for a preventive maintenance.

I fully agree with your logic @Spiff I would love to sell a tone of seals, but people would get pretty upset when they tried to fit them. The price will not be so bad though, it should be less than 200€ inc tax and labour. Great feedback though.

 

[Spiff]

If you make a good youtube video with the instructions, you'll sell a ton of seals, and nobody should complain if they did not follow the instructions.

You do a great job, thanks for posting here.

 

[hainman]

@Bearing Man whats the price for a full service on the Bosch gen4 motor
My last bike I had to get crankshaft bearings done and there was wear on the shaft which caused a slight bit of play when you move the crankshaft side to side
Don’t have as much issue on this motor,wondering if doing a lot of towing a mate on his analogue bike maybe contributed to the damage
Is the seal kit a worth while upgrade??
My motor is almost 2 years now and out of warranty

 

[Bearing Man]

@Bearing Man whats the price for a full service on the Bosch gen4 motor
My last bike I had to get crankshaft bearings done and there was wear on the shaft which caused a slight bit of play when you move the crankshaft side to side
Don’t have as much issue on this motor,wondering if doing a lot of towing a mate on his analogue bike maybe contributed to the damage
Is the seal kit a worth while upgrade??
My motor is almost 2 years now and out of warranty

Can't really write prices on here, post stay forever but the prices change. Please take a look at our site here: Repair & Overhaul Service (New) - eBike Motor Centre (Performance Line Bearings) Towing your mate, should not really cause the motor any significant issue, it's just like you, but going up a steeper hill.
If' you're riding off road or in wet conditions, the upgrade is a must have!

 

[hainman]

Can't really write prices on here, post stay forever but the prices change. Please take a look at our site here: Repair & Overhaul Service (New) - eBike Motor Centre (Performance Line Bearings) Towing your mate, should not really cause the motor any significant issue, it's just like you, but going up a steeper hill.
If' you're riding off road or in wet conditions, the upgrade is a must have!

I ride in Scotland 90% or my riding is in the wet and Mud

 

[Bearing Man]

I ride in Scotland 90% or my riding is in the wet and Mud

Yes then, definitely yes!

 

[Lithovatis]

Yes then, definitely yes!

New to the forum Bearing man . Regarding grease .
Is it safe to use Belray waterproof grease instead the bosch for the crankshaft protection rings ?????

Best regards !

 

[Bearing Man]

As long as it's not aluminium based like some of the marine greases, you should be fine. However, just ensure it is good and tacky.

 

[Lithovatis]

Waterproof Grease

Excellent protection from dirt and saltwater.

www.belray.com

As long as it's not aluminium based like some of the marine greases, you should be fine. However, just ensure it is good and tacky.

No idea mate . No idea what tacky is (am Greek ) .

Also i can find this as well here in Greece :

Motorex Bike Grease 2000 850gr​

Thnx for the reply i appreciate it ......
Got 7 Orbea for my business .

 

[Bearing Man]

Waterproof Grease

Excellent protection from dirt and saltwater.

www.belray.com

No idea mate . No idea what tacky is (am Greek ) .

Also i can find this as well here in Greece :

Motorex Bike Grease 2000 850gr​

Thnx for the reply i appreciate it ......
Got 7 Orbea for my business .

κολλώδες is tacky or sticky. Motorex Bike Grease 2000 is perfect.

 

[Lithovatis]

κολλώδες is tacky or sticky. Motorex Bike Grease 2000 is perfect.

Thnx Peter .

One more question pls.....
The c-clip on the crankshaft doesn't have holes.....
What kind of pliers should I get cause can't find something looking after at Greek stores that suits......

 

[Stihldog]

Thnx Peter .

One more question pls.....
The c-clip on the crankshaft doesn't have holes.....
What kind of pliers should I get cause can't find something looking after at Greek stores that suits......

If you can’t get specific pliers then a modified Cir-clip plier(s) will work. That’s what I did. There’s a number of pictures posted here (I have posted also) that could help.

I ground off the small pins and thinned out the tip slightly. You may need to sacrifice a tool, or part of a tool, but it works fine for removing that C-Clip.