Clicking/knocking sound Bosch CX Gen 4 motor

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joejoejoe

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Hi
I have a Bosch CX Gen 4 motor on a Cube Stereo Hybrid 160 HPC. It has developed a moderately loud clicking/knocking noise when the left crank is at 7 O’clock this only happens under load and ONLY when the bike is switched on, it is silent when the bike is turned off. Have you any ideas what the issue is and if so is it an easy or difficult fix?
I would be grateful for any help you can offer.
Joe
 
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There’s a few simple things you can do before a motor repair or replacement.
Check your motor mount bolts(6). Check the peddle shafts. Remove the chain and spin the crank. Listen for noise. Insure the crank(s) is torqued correctly.

A LBS can definitely help with the issue but the Bearing Man may be able to fix the motor rather than a replacement.
 
It only makes the noise when the bike is powered ON and under load and clicks/nocks at exactly the same point on each revolution of the crank, no noise at all when the bike is ridden switched off no matter how hard you pedal. The brackets and mounting bolts have all been checked. The motor has been removed and refitted twice.
 
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Sounds like a mystery. If it’s an internal motor issue, your LBS or bearing man may be able to diagnose the problem. That sound would drive me crazy too 😜
 
I know you say the conditions under which it happens but a noise at one point of crank rotation is weird! Are you sure the right side crank or chainwheel is not hitting the chain guide??
 
Not too sure if it helps but have you tried taking the crank off, cleaning the splines on the motor and the crank, adding grease and installing?

I've encountered similar issues on ebikes where you have an alloy crank. 9/10, the problem is resolved👍🏿
 
It has been with the bike shop for over a month now they have removed and refitted the motor several times. The noise must be coming from the motor as it is ONLY PRESENT WHEN THE BIKE IS SWITCHED ON. They are wanting to send the motor to Bosch which they say may take a couple of months.
I tried the bearing man first but he thought the noise was coming from a loose motor bracket and that there is nothing inside the motor that would cause a regular clicking noise. I find this VERY odd as I explained there is no noise at all when the bike is switched off no matter how much torque you put through the pedals. Surely there is much more stress being put on the motor, mountings frame etc when the motor is OFF and the bike is pedaled hard?
I have asked them to try the motor on a different bike which they are going to do today.
 
Had the same thing a couple of years ago on a trek rail, tried everything before I went down the motor route , removed chain guide , checked cranks, chainring nut , motor mount bolts , pedals ,wheels, suspension pivots , gorpro'd the noise whilst pedalling up a hill , LBS replaced under warranty , had no loss of power or fault codes , motor worked well, just knocked.
 
Keifo H said:
Had the same thing a couple of years ago on a trek rail, tried everything before I went down the motor route , removed chain guide , checked cranks, chainring nut , motor mount bolts , pedals ,wheels, suspension pivots , gorpro'd the noise whilst pedalling up a hill , LBS replaced under warranty , had no loss of power or fault codes , motor worked well, just knocked.
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Ditto. It was the coming from the left side, definitely position-dependent, pedal at 10–11 (when facing non-drive-side). It didn’t require load on the pedal to cause it to click. I’m not sure if I also felt it in my foot or just an aural haptic effect. I made a video of it and showed it to the Trek shop. I also felt the slightest amount of play in the spindle that wasn’t present in other motors. That seemed to be enough for Bosch to replace the motor. I brought it in a week before the warranty expired (this was a year ago).

Someone told me that the warranty resets when a motor is replaced … anyone know if this is true? And If so, is it documented somewhere?
 
markloch said:
Someone told me that the warranty resets when a motor is replaced … anyone know if this is true? And If so, is it documented somewhere?
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I've had my Whyte e-160s since 2020 and follow lots of groups.
Although I can't find it documented, I can say that initially the warranty did begin again when a new motor was fitted but over the years I noted that people were posting that this had changed and the warranty date stays as the original warranty date.
 
joejoejoe said:
It has been with the bike shop for over a month now they have removed and refitted the motor several times. The noise must be coming from the motor as it is ONLY PRESENT WHEN THE BIKE IS SWITCHED ON. They are wanting to send the motor to Bosch which they say may take a couple of months.
I tried the bearing man first but he thought the noise was coming from a loose motor bracket and that there is nothing inside the motor that would cause a regular clicking noise. I find this VERY odd as I explained there is no noise at all when the bike is switched off no matter how much torque you put through the pedals. Surely there is much more stress being put on the motor, mountings frame etc when the motor is OFF and the bike is pedaled hard?
I have asked them to try the motor on a different bike which they are going to do today.
Click to expand...
Although it is not impossible that this noise is coming from the motor, it is normally unlikely. Most components inside the motor rotate at a different speed to the pedals, so the only thing inside the motor that revolves at the same speed as the pedals is the crankshaft. Everything else is geared from the crankshaft and rotates faster or slower, this presents the noise in a different place, each time the pedal is rotated.
It is almost always the case that these noises disappear when the motor is switched off because no matter how hard you pedal, you have removed the extra 300 to 400% of extra power that the motor would supply, removing much of the twisting forces required to make such a noise.
There is nothing but two bearings and the crankshaft rotating at pedal speed, and bearings don't usually click or knock. This is why we tell people to check the motor mounts, crank arms, spider nut, spider to chainring bolts, pedals, seat post, suspension linkage, rear cassette, freewheel hub, rear axle... etc.
If nothing is found, then it's time to look at the motor.
 
I had a clicking I was convinced was the motor until I traced it to a bad freehub bearing. the thread in here ran to four pages. anyway, the lbs should have put in another bike by now, which should answer things, no?
 
I have the exact same problem and Bosch have said it is not the motor....I have had the noise on the same bike as the OG....Cube Stereo 160, for about 2 months and it deosnt seemt o do anything other than make a noise.....LBS have heard it and are equally confused....will check free hub bearings but they should be OK...the rear wheel was built up from new only months ago wiith all new components.
 
front suspension can make like a clicking sound when you pedal, try changing the rebound from one extreme to the other and see if it's just that.
 
Same noise when the motor was put in a different bike. They still don't know what is causing it.
 
New motor was fitted under warranty last week and I've done around 200 miles without any clicking/knocking noises. The LBS didn't do any work to investigate which part of the motor was at fault but Bosch replaced it without question or any explanation. So I am guessing Bosch know what the issue is. The motor had only done 450 miles from new.
 
I have a similar problem. I can notice a clicking noise through the left pedal (can feel the click through my shoe). This happens after a few kms and it's most noticeable (strongest click) in turbo, less so in emtb and nothing in other modes.
Checked pedals, cranks, didn't take the chainring off yet but there's no wobble as far as I can determine.
The motor is out of warranty, so I wonder what a replacement can cost if it comes to that...
 
Eliadn said:
I have a similar problem. I can notice a clicking noise through the left pedal (can feel the click through my shoe). This happens after a few kms and it's most noticeable (strongest click) in turbo, less so in emtb and nothing in other modes.
Checked pedals, cranks, didn't take the chainring off yet but there's no wobble as far as I can determine.
The motor is out of warranty, so I wonder what a replacement can cost if it comes to that...
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This is absolutely classic motor bracket creak or click. This happens when the motor mounting plates are moving against the frame or motor body. The "click" is caused because the mounting plate bolts and screws are tight, but just not tight enough. This allows the aluminium motor plates to grip the bikes frame up to a certain point and then slip with a "click" or "creak". The motor basically tries to twist in the frame and this is why the noise gets more noticeable under load.
Re-torque your motor mounting bolts and screws, then try it again. Do not remove the mounting plates and grease them, this will make them quiet for about three weeks and then it will be worse than ever. If you do anything, remove the mounting plates and clean them and the mounting surfaces with a de-greaser, you want the aluminium brackets to grip, not slip.
 
That makes sense, will try that! What are the torque values? The frame is aluminium.
 
Eliadn said:
That makes sense, will try that! What are the torque values? The frame is aluminium.
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The 6 Torx Plus 40 (TP40) bolts that hold the motor to the frame should be tightened to 20Nm
The 8 Torx Security 25 (TS25) machine screws that hold the mounting brackets to the motor are 8Nm
The later Bosch "Smart" Gen 4 mounting brackets have Torx 30 (T30) torqued to 9.5Nm.
 
Eliadn said:
That makes sense, will try that! What are the torque values? The frame is aluminium.
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My neighbour left this issue/sound for too long. The results were a a small frame crack in the motor mount insert and sheared bracket bolts.

This sounds recently happened to me and I immediately addressed it. I had to drop the motor and re-torque all the bracket bolts (8) but I added some blue loc-tight to all the bolts.

I now recognize the sound or how the sound happens (if that makes sense?)
 
Stihldog said:
This sounds recently happened to me and I immediately addressed it. I had to drop the motor and re-torque all the bracket bolts (8) but I added some blue loc-tight to all the bolts.
Click to expand...

Those dinky screws into the case are a şħĩťťŷ way to mount a motor. Mine started creaking when there were about 900 miles on the bike. ALL the screws were loose.

Was the OP's problem actually the motor, or was it the brackets which were only removed from the old motor when the new motor arrived? There's no way to know for sure, and on matters like this I'm skeptical of hearsay reports.
 
RustyIron said:
Those dinky screws into the case are a şħĩťťŷ way to mount a motor. Mine started creaking when there were about 900 miles on the bike. ALL the screws were loose.

Was the OP's problem actually the motor, or was it the brackets which were only removed from the old motor when the new motor arrived? There's no way to know for sure, and on matters like this I'm skeptical of hearsay reports.
Click to expand...
I agree. Those brackets seem like an afterthought. I like the new mounting for the Gen5 CX motor.
 
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