FLX mid drive disassembly

[Old Engineer]

Retired, retarded engineer taking apart the mid drive of a Roadster. 149 miles and then stored indoors since new. Rode OK as a bike but when a battery was connected and ridden the crank no longer engages. Anyone been inside one of these?

 

[HumanPerson]

Hey, Welcome to the forums

 

[HumanPerson]

Do you have any pics of this ebike and motor system?

 

[Old Engineer]

The bike was purchased as is. Dusty from indoor storage. Molding tits still on tires. Protective film still on display. Battery obviously failed over years of storage since 2016? Rode as a conventional bike with no issues while researching battery options. Temporary attachment of replacement battery shown. Odometer shows 149 miles when powered. After the first powered ride the crank would not fully engage. Learning curve, all square shafts are not the same dimension. Universal tool purchased screws into crank as expected but refused to push off. Finally cut crank on right side to remove. Discovered that bearing cap on tool is larger than the square. Engineered a way to push and left crank came off as designed. Preparing to disassemble drive. 40+ years as a hands on troubleshooting electrical/mechanical engineer, now to see what this is made of and how it works!

 

[Smaug]

Don't know, but welcome, from SE Wisconsin anyway!

 

[Old Engineer]

Thanks from WTX! Persistence pays off. I finally found an obscure note referencing a link to the FLX site where a video was posted about planetary gears and clutch. A used gear assy was listed for sale and the video showed the replacement procedure, including the special tools needed that were included with the sale of the gear assy. Most tools I have and the verbiage associated with the one I do not came up in a search. An offering from Amazon arriving tomorrow appears to be identical and quickly available. Video even demonstrates that the chain ring attachment is left hand threads. Given the history and symptoms I expect to find the dogs in the clutch gummed up in old grease. With luck a cleaning and replacement with fresh grease will address the issue.

 

[m@Robertson]

If it helps at all, that motor is manufactured by Bofeili. The clutches in those motors were a known weakness. I had that same motor in my Luna Fixed bike, but I sold it on before there was ever any need to perform any motor maintenance.

 

[Old Engineer]

Interesting! Thanks for the historical note. I spent many years working on design issues and weaknesses. Perhaps that will come in handy a I chase this problem.

 

[Old Engineer]

On disassembly no problems found other than the clutch. Soaked the clutch in solvent and washed thoroughly. All indications afterwards were that it was free and functioned as expected. On reassembly the clutch broke free again and now slips with very little force applied to the crank.. Motor easily takes the bike to 20 MPH. All searches for repair parts fail. If a new clutch is not available the only potential I see would be if there is another mid motor assembly that is sized the same but I doubt that the electronics could be adapted. Freeze the crank to the chainring, remove the battery and have a very nice nine speed bike? BTW it seems the bike is a Trail, not a Roadster.