Anyone ever replaced a CX Gen 2 for the new Gen 4

EdTy

New Member
Mar 31, 2021
3
1
Chile
Quite happy with my current e-mtb but wouldn't mind upgrading the Bosch Gen 2 CX motor for a new Gen 4.
Has anyone ever tried this? Easy or difficult?
 

Mteam

E*POWAH Elite
Aug 3, 2020
1,804
1,741
gone
Will a gen 4 fit in the place of a gen2? Isn't the gen 4 a lot smaller than the gen 2 and the mounting bolts in different places?
 

cemoz

Member
Jul 12, 2020
34
32
Australia
I was hoping to do it, was studying product design and I still couldn’t get hold of the gen 4 motor by itself.Tried for over a year, Bosch their distributors or any LBS that stock them will not sell you one. It’s only available as a replacement (gen 4 for gen 4) the only way you will get one is through eBay and they don’t come up that often.

If I go back to working on the project I was trying to get it for I’ll probably buy the cheapest hard tail I can find with the gen 4 and take the motor out of that.
 

EdTy

New Member
Mar 31, 2021
3
1
Chile
I was hoping to do it, was studying product design and I still couldn’t get hold of the gen 4 motor by itself.Tried for over a year, Bosch their distributors or any LBS that stock them will not sell you one. It’s only available as a replacement (gen 4 for gen 4) the only way you will get one is through eBay and they don’t come up that often.

If I go back to working on the project I was trying to get it for I’ll probably buy the cheapest hard tail I can find with the gen 4 and take the motor out of that.
Thanks cemoz.
As mentioned above by other members its seems doable since its a smaller motor, and would probably need some kind of adapter to fill in the empty spaces.
Amazing that Bosch won't sell you the stand alone motor, some kind of deal with manufacturers to promote new bike sales??? or maybe they want to make sure their motors are installed correctly?
I'd be interested in learning if you ever manage the switch.
 

EdTy

New Member
Mar 31, 2021
3
1
Chile
Thanks cemoz.
As mentioned above by other members its seems doable since its a smaller motor, and would probably need some kind of adapter to fill in the empty spaces.
Amazing that Bosch won't sell you the stand alone motor, some kind of deal with manufacturers to promote new bike sales??? or maybe they want to make sure their motors are installed correctly?
I'd be interested in learning if you ever manage the switch.
BTW, just found this listing on ebay if your interested.
1617410343510.png
 

Bearing Man

Ebike Motor Centre
Patreon
Sep 29, 2018
889
2,123
UK
We have looked at this several times and the Gen 4 is not only smaller it is much narrower. It could be made to fit and would plug into existing battery and controls, but getting around crank centralisation and going from a small chainring to large, this has to line up and miss everything while keeping the motor central in a bigger hole without the crankarms hitting the frame or swingarm. To be honest there are absolutely no benefits and much grief.
Later this year when the madness dies down, we will be looking at an engine swap that would keep the older bikes going and would definitely be worth the effort. :) ?
 

cemoz

Member
Jul 12, 2020
34
32
Australia
Thanks for the look up of the gen 4 EdTy, I hope to go back to it at some point. Just haven’t got the time to mess around with mounting plates and sorting out the crank chain line at the moment. I picked the frame up by itself from Germany last year it’s rear end was going to be modified as well. I got sick of it just sitting there so are building it up with the gen 2 so it’s at least rideable for now.
 

Cobee

Member
Apr 30, 2023
21
36
Poland
Hi, I’m in progress.
I’am not sure that will be work perfect. I will check it , I like it :)
Bike Trek Powerfly 9,7 lt plus 2019 in carbon.
Mount plates made from stainless steel 1,403 cutted on laser and milling.
Later I will design Alu covers.
CF8889DA-CBB2-46DA-9821-84BB54A55244.jpeg
8475E1E0-10DD-44EF-BD0A-39B79607C9BD.jpeg E4D42ECE-3C8E-4F2C-8A80-F6129007109C.jpeg 9471B2D2-FF7B-4CBB-91E2-9809D911FE0A.jpeg 8917AD24-CC38-4390-ADD7-63CF7138BC9A.jpeg 7B0BCD9B-36D3-427D-9842-73112EB2F334.jpeg
 
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2wheelsahead

Member
Feb 22, 2023
33
12
Wrexham

Cobee

Member
Apr 30, 2023
21
36
Poland
first feeling - quite ok. but I was try found which motor is stronger, more aggressive. I think that gen2 is very good motor comparing with gen4. I have a good comparison ( two motors on the same bike). and I’m still thinking to go with this far or back to old. Because is not big different with power.
Old motor have some disadvantages.
Noisy / sharp start stops / heavier /
 

Bearing Man

Ebike Motor Centre
Patreon
Sep 29, 2018
889
2,123
UK
first feeling - quite ok. but I was try found which motor is stronger, more aggressive. I think that gen2 is very good motor comparing with gen4. I have a good comparison ( two motors on the same bike). and I’m still thinking to go with this far or back to old. Because is not big different with power.
Old motor have some disadvantages.
Noisy / sharp start stops / heavier /
I still think that if you can keep it dry, Bosch Gen 2 is one of the best motors built to date. It's built like a tractor gearbox inside and uses mostly tried and tested vehicle components in the electronics. The PCB is mounted at the top of the motor, so it's not sitting in the water if any gets in and for an extra kilogram you get a motor that would knock a tree over whilst towing your mate and carry on!
 

Bearing Man

Ebike Motor Centre
Patreon
Sep 29, 2018
889
2,123
UK
I was sell gen4 today 😁😟
Bearingman. My gen2 have a ca. 2000km. On crank I feel small loose maybe 1-2mm on crank end. Noises are quite standard. When should I implement repair kit ? I found Zestaw naprawczy Bosch silników 2 generacji
Ca.100$

You are right - motor is like tractor 🤪
That is not a lot of mileage, so I would be very surprised if you need a service kit just yet, unless you spend a lot of time off road in mud and water. If the bearings were damaged or worn, you would hear a rough sounding noise! If you fit this service kit DO NOT fit the felt seals, they will destroy your motor, throw them in the bin!
 

Cobee

Member
Apr 30, 2023
21
36
Poland
Thanks. Here are adapters on my second bike trek Powerfly 9.9. Right, engine mount are the same.

20240323_083558000_iOS.jpeg 20240323_083635000_iOS.jpeg 20240323_083615000_iOS.jpeg
 
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