My 2020 Rail 9.7 had a creaking noise for some time. The creaking was minor at first but got progressively worse to the point others riding near me could hear it. I had taken all the pivot points apart and cleaned and retorqued them and cleaned seat post but still did not fix the creaking noise. Finally the only thing left was the motor mounting. I had noticed while holding the brake and stepping on the crank that the motor had a slight movement to it. I removed the motor and found the bolts for the motor mounting bracket were loose and one had broken off. I was able to remove the broken bolt. For some reason Bosch had installed them with tamper proof bolt heads and did not have any anti-seize on them. I removed the other 3 loose bolts and installed 4 new M5-18 X 16mm bolts with regular allen heads. Installed them with anti-seize and torqued them to 6 nm. Reinstalled them motor and have 2 rides for 40 miles and not more creaking. Bracket shown in the attachment.
Trek Rail Creaking Noise
- Thread starter Ezliven
- Start date
I dropped my motor out yesterday and checked the M5 bracket screws - got a little bit of turn out of the front most ones at 8Nm.
Why did you use anti-seize rather than thread locker (Loctite 242 Blue for example)?
My dealer has drilled and tapped a few M5 motors and fitted M6 screws for this issue (later motors come out with M6).
Why did you use anti-seize rather than thread locker (Loctite 242 Blue for example)?
My dealer has drilled and tapped a few M5 motors and fitted M6 screws for this issue (later motors come out with M6).
My bad. I meant to say thread lock Loctite blue not anti-seize. Did yours have star tamper proof heads? Trek customer support didn't know for such and said should be safe at 11Nm. I tried torqueing to 11 but they felt like they were going to twist the head off. 6Nm was about all I felt safe with. I can't imagine why Trek used such small bolts and the bolts are just regular grade soft metal. Drilling the broken bolt out was no problem what so ever.
You're right to apply your judgment to that torque value - even screw manufacturers don't recommend more than 9.5Nm for M5 0.8 pitch screws. I think 11Nm is for initial installation of M6 screws on later motors.
Mine have those stupid security penta-lobe heads. I guess Bosch don't want folk touching them, which might have been ok had they specified a stronger class M6 screw in the first place, I didn't want to remove crank & chainring so I used a grinder to shorten a security bit to check the two front RHS screws. I'll probably replace them with serrated-flange socket head screws grade 8.8 or higher.
Mine have those stupid security penta-lobe heads. I guess Bosch don't want folk touching them, which might have been ok had they specified a stronger class M6 screw in the first place, I didn't want to remove crank & chainring so I used a grinder to shorten a security bit to check the two front RHS screws. I'll probably replace them with serrated-flange socket head screws grade 8.8 or higher.
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