Trek Rail 9.8 Clunk

[BobMtnBkr]

New ’21 Trek Rail 9.8 XT clunks and rattles over big bumps. Is there a consensus as to what is causing the knocking noises and recommended fixes? My forum search was inconclusive. Thanx...

 

[Barks507]

New ’21 Trek Rail 9.8 XT clunks and rattles over big bumps. Is there a consensus as to what is causing the knocking noises and recommended fixes? My forum search was inconclusive. Thanx...

It's backlash in the motor. Some people get it worse than others. There is lots of reading material on here about it. It bothered me at first but now I hardly notice it.

 

[BobMtnBkr]

Thanks for feedback. I will continue to research. I’m ok with it as long as it isn’t hurting anything.

 

[Oupy]

Could also be the battery a bit loose (have a look here: Trek RIB Battery Alignment Procedure - Updated - EMTB Forums)
Could definitely be backlash as mentioned above, that will generally be most noticeable when above the limiter over choppy terrain.

 

[BobMtnBkr]

Have 115 miles on bike and the clunking seemed to be getting worse. Found contact marks on the bottom of the battery and bottom of the inner frame tube. Also noticed RIB brace had not been installed (contrary to what the LBS said). LBS is installing RIB brace and misc. parts per SERVICE MANUAL SUPPLEMENT Rev 1 June 2021. Hopefully this will fix the clunking noise.

 

[Ushtang]

Have 115 miles on bike and the clunking seemed to be getting worse. Found contact marks on the bottom of the battery and bottom of the inner frame tube. Also noticed RIB brace had not been installed (contrary to what the LBS said). LBS is installing RIB brace and misc. parts per SERVICE MANUAL SUPPLEMENT Rev 1 June 2021. Hopefully this will fix the clunking noise.

This is what did it for me. After this was fitted, clunking from battery was totally gone.