Bosch Performance CX creaking sound

[Richardsuperstar]

I have a Trek Rail 9 which like many has the usual creaks and clicks.

I think i have narrowed mine down to the mounting plates on the motor. There appears to be 8 Torx T25 bolts holding these plates to the main motor one of which seems to have come loose and the others dont seem to be that tight.

The question is though how tight do these need to be. I found a maintenance manual on here for Bosch motors which states these plates are secured up to 11nm but that seems pretty much for what I believe is a M5 thread.

Other than that I can't find any other info other than the main 6 that holf the motor to the frame.

So any ideas much appreciated.

 

[slomtbr]

Page 10
https://www.emtbforums.com/attachments/diagram_2020_rail_alloy-pdf.33082/

 

[Richardsuperstar]

The figure stated in the guide is for the motor guard but I guess it would seem logical the same size bolts here would have the same values.

 

[slomtbr]

I've seen 8Nm and blue Loctite.

 

[Richardsuperstar]

I've seen 8Nm and blue Loctite.

I don't suppose you recall where you saw that as so far I've seen figures between 6-12 stated. I attempted to ask bosch but obviously no help.

 

[slomtbr]

I can't find it, but since 8 is between 6 and 12 …

 

[Chairman]

Keep an eye on these bolts. It's a known issue that they can come loose. I actually managed to snap the alloy mounting bracket. Definately locktight

 

[Richardsuperstar]

Keep an eye on these bolts. It's a known issue that they can come loose. I actually managed to snap the alloy mounting bracket. Definately locktight

How tight did you do yours back up to?

I emailed a website that rebuilds/reconditions these units sending him the diagram highlighting the bolts and the reply was 20nm personally I'm not seeing that size bolt take 20

 

[MrPeaski]

20Nm is for the big bolts that go through the frame into the plates (No54 in the above pic) and that is for aluminium frames.
The smaller bolts should be 6Nm and all bolts loctited.
(coming from the Cube area and a carbon frame 11Nm for big frame bolts, 6Nm for plates to motor)
HTH

 

[Richardsuperstar]

I noticed on another forum someone mention damping film which I assume goes between the mounting plate and frame.

Is this a thing for the gen 4 motors and does it work?

 

[Chairman]

Keep an eye on these bolts. It's a known issue that they can come loose. I actually managed to snap the alloy mounting bracket. Definately locktight

I do mine to 8 nm

 

[Expidia]

20Nm is for the big bolts that go through the frame into the plates (No54 in the above pic) and that is for aluminium frames.
The smaller bolts should be 6Nm and all bolts loctited.
(coming from the Cube area and a carbon frame 11Nm for big frame bolts, 6Nm for plates to motor)
HTH

@MrPeaski I just turned 74 and I like the quote in your signature! It made me stop and think of all the people I knew and lost over my years after I read it . . . and appreciate the fact that "I'm" still here!

 

[Expidia]

Better to just call Trek customer support and ask them the torque settings. Of course Loctite would be a good idea, but as with most stuff made these days the hardness of the bolts they use are not the best anymore. I had a creaking in my seat that was driving me crazy, so I started tightening up something as simple as the two bolts that secure the seat to the rails with my torque wrench but did not know the proper torque setting and one just snapped way too easily!

Many of the bolts torque settings are a lot lower than I thought they would be. I called Trek c/s and he pointed me to a place on their site that I printed out a list of many of the torque settings. I also noticed some of Trek's bolts have tiny Nm numbers next to them that I never even noticed as they were so small.

From my sheet I printed out for my model some of the bolts don't even show a torque setting so it's best to call them rather than snap one and then waste your time hunting down a replacement like I did. I wound up having to order another one at my local Trek store and wait like 5 days for it to come in.

 

[Richardsuperstar]

Trek is my next port of call but as its part of the Bosch motor I doubt they'll tell me. The bolts from frame to the mounting plates are 20nm, information that seems to be easily found but the bolts from the plates to the motor are one of the mysteries of the universe.

When I emailed Bosch they told me that if a customer touched those bolts then they'd treat the unit as being opened. To which I said that makes no logical sense to anyone. Surely it would just be easier make this value available to save people damaging the unit and having more trust in the brand... No reply.

I've just gone with 6nm for the minute and being slowly driven insane with the creaks as I cycle home. Off road I don't notice it.

 

[Bearing Man]

Bosch state that the TS25 (Torx Security 5 point) screws are:
First time used 10Nm.
If being refitted or re-tightened for a second time 9.5Nm
The larger TP40 (Torx Plus) screws holding the mounting plates to the frame should be 20Nm
Do not use a standard Torx "T40" bit! You may get away with it once or twice but it damages the torx splines inside the bolt and they will strip.

 

[Richardsuperstar]

I don't suppose you have the manual/pdf to where they state these figures. I found one for the performance and not the cx version where it states 11nm so theres so many figures floating around.

Luckily I did notice they were plus torx on the frame bolts and got myself a socket bit and my drive just has normal t25 heads not the security type.

 

[Bearing Man]

I don't suppose you have the manual/pdf to where they state these figures. I found one for the performance and not the cx version where it states 11nm so theres so many figures floating around.

Luckily I did notice they were plus torx on the frame bolts and got myself a socket bit and my drive just has normal t25 heads not the security type.

This is directly from the 2023 Bosch eBike manual. I cannot copy or reproduce this manual or parts of it due to copy write infringement. We do this for a living so please trust that the information stated is correct.

The early Gen 4's did have standard T25 machine screws fitted. Bosch do not state any torque figure for these in their 2020 Manual. Personally, I would be carful taking these early screws to 9.5Nm

There is a "non CX" Performance Line version of the Gen 3 and Gen 2, 3 and 4 are often confused on the internet.

If you do decide to tighten your motor mounts, drop the motor first and clean any grease from between the mount and the frame using a solvent or brake cleaner etc. This will allow the aluminium to bite together and stop slippage. Grease will usually only stop creaking for a short period of time before it all starts again.

 

[Richardsuperstar]

Thanks for the replies.

So it would appear if I do have one of the first versions with the normal t25 heads and nothing was mentioned in the workshop manuals then it looks like I'm just to roll 2 dice for a figure.

I only started worrying about this because I checked one of the screws and I could easily turn it with a srewdriver. Then I found some info that they should be 11-13nm which seemed a bit excessive. So did them to 6 but now I'm thinkng that's too low

 

[Richardsuperstar]

I happened to come across this so I'm hoping the stated (8nm) is the magical figure.

@Bearing Man is the kind of manual you got the 9.5nm from?

 

[Bearing Man]

View attachment 106152
I happened to come across this so I'm hoping the stated (8nm) is the magical figure.

@Bearing Man is the kind of manual you got the 9.5nm from?

No, what you have found is the paper sheet that comes with new mounting plates. I am gobsmacked that they tell you that you will need a 1Nm to 10Nm torque wrench, but then don't tell you what torque you should tighten it to!

I got my information from the Bosch 2023 eBike Manual. This is the 245 page manual that you can purchase as a Bosch agent, or be given when you attend the Bosch Service Engineer training (as I and my staff have).

 

[Richardsuperstar]

 

[Bearing Man]

View attachment 106183

reading never was my strong point! anyway, sod the copyright.

 

[Richardsuperstar]

That may be it then. In those instructions the bolts mentioned are t30 m6 where as the other on the heads are t25 m5. Not sure why 2 different size bolts are being used but seems logical the smaller would have a lower torque value.

The mystery is slowly unravelling

 

[Bearing Man]

I think the torque settings are for initial torque which will stretch the bolt. And if this bolt needs to be re-torqued it should then be torqued to 9.5Nm so as not to snap the already stretched bolt. This would all make sense for a T25 5mm bolt or screw, but T30 are usually set from 9Nm to 11Nm without stretch! So I guess we're no further forward!

 

[Richardsuperstar]

I guess the only thing left for me to do is locate some good threadlock and snapped bolt extractor and have a go.

 

[Sijmes]

Did you manage it ?

 

[Richardsuperstar]

I did it yesterday. Undid screws one by one, slapped some Loctite on and torqued up to 8nm. The weather is horrendous today so will test out tomorrow. Plus wasn't sure how long that Loctite would take to fully set.

 

[Sijmes]

I've just redone the loose ones on my Jam2. One of these has come loose for the second time. Ive used extra strong lockite this time. It starts creaking whilst pedaling. Hopefully, if one of these bolts rips some threading out, there will be enough material to re-thread up to M6. The buttonheads on these smaller bolts are getting tired, even with the correct tool. I've scoured the internet for a replacement, but have been unable to find something similar, without buying a box of 100 pieces. Anybody have an address?

 

[Richardsuperstar]

I used Loctite 290

 

[Richardsuperstar]

Well I hate to say its made no difference. So it seems the only way to get rid of the noise is to get rid of the bike which is probably my next move and get one without a Bosch motor or better still a human powered one.