Bafang M620 Ultra motor broken? Low torque problem. Best retailer for US?

[Deacon Blues]

I took my ultra apart when it had less than 1500 miles on it because I thought the motor was getting noisy.
To my surprise I found very little grease surrounding the gears and there was a noticeable amount of gear tooth wear.
I ordered three new gears from GBK, but didn't order the motor rotor, with the small gear, because mine, at first glance, didn't look worn and mine also has the X1 controller, which is a whole other problem.
Taking a closer look I realized that the motor rotor gear was also worn.
I ended up not replacing the gears, thinking that the old, worn motor rotor gear would, over time, damage the new gears. Instead, I adding corn head grease and put the motor back together.

 

[DDBB]

How many miles since you put it back together? Still quiet?

 

[MartsEbike]

I had the exact same experience as @Deacon Blues , premature wear on the rotor gear due to a lack of factory grease.

But I did change all the gears, and done a "quiet gears" upgrade at the same time.

(I don't really advise others do the "quiet gears" upgrade, its a PITA, requires a new controller and calibrating... this will add a few hundred dollars to your bill. And it doesn't make it THAT much quieter by itself. It still needs grease!)

But yes, even steel gears can wear down in just hundreds of miles without grease.

It may sound silly on a new motor, but for piece of mind open it up and check how much grease is there, and add a generous amount for good measure. Use SHC100 or Cornhead Grease.

It would be worth purchasing the gaskets from GreenBikeKit before you do this in case you break them during the regreasing.

Bafang Ultra M620 G510 motor gasket-greenbikekit.com BBS, ebike batteries, Bafang M620, Bafang M600, Bafang M500, Bafang M510, KT controller with display-GreenBikeKit.com

Bafang Ultra M620 G510 motor gasket

www.greenbikekit.com

 

[il Munduato]

Yeah I waited 1000 mi before opening up a new motor but I found everything OK and though skimpy.. an adequate amount of factory grease.
Since my new motor will be arriving not installed in a bike... I may open it up on the bench.

 

[Deacon Blues]

I had the exact same experience as @Deacon Blues , premature wear on the rotor gear due to a lack of factory grease.

But I did change all the gears, and done a "quiet gears" upgrade at the same time.

(I don't really advise others do the "quiet gears" upgrade, its a PITA, requires a new controller and calibrating... this will add a few hundred dollars to your bill. And it doesn't make it THAT much quieter by itself. It still needs grease!)

But yes, even steel gears can wear down in just hundreds of miles without grease.

It may sound silly on a new motor, but for piece of mind open it up and check how much grease is there, and add a generous amount for good measure. Use SHC100 or Cornhead Grease.

It would be worth purchasing the gaskets from GreenBikeKit before you do this in case you break them during the regreasing.

Bafang Ultra M620 G510 motor gasket-greenbikekit.com BBS, ebike batteries, Bafang M620, Bafang M600, Bafang M500, Bafang M510, KT controller with display-GreenBikeKit.com

Bafang Ultra M620 G510 motor gasket

www.greenbikekit.com

The only thing I'd add is buy an extra gasket, because sh*t happens.

 

[MartsEbike]

I should also say as I didn't really make it clear earlier but ANYTIME you change the rotor gear you risk the chance of having to recalibrate... Because its not easy to tell which way the magnet is pointing on the shaft and it'll mess up the hall sensor position!

You might get lucky, but chances are you'll find it running rough! To fix you need a buy a special C961 "Calibration" display, and compatible controller - and chances are your existing controller won't be compatible - so you'll be replacing that too.

So try avoid this issue...

 

[DDBB]

So if you've got a worn rotor gear you're basically screwed?

 

[MartsEbike]

So if you've got a worn rotor gear you're basically screwed?

Its possible to fix it but the motor will may need calibrating again.

Its better to just make sure the grease is good from the start.

 

[il Munduato]

That's interesting... I hadn't heard that some controllers are compatible with the C961 and/or couldn't be synchronized. How can you determine? Older ones?

To get the quiet gears I'm swapping a complete motor... Not worth getting into the weeds and all that extra work for a few dollars. Plus I now have a complete working spare, easy to swap out with minimal down time.

 

[MartsEbike]

That's interesting... I hadn't heard that some controllers are compatible with the C961 and/or couldn't be synchronized. How can you determine? Older ones?

To get the quiet gears I'm swapping a complete motor... Not worth getting into the weeds and all that extra work for a few dollars. Plus I now have a complete working spare, easy to swap out with minimal down time.

Yep its annoying but you need a controller with the model number CR R10M.1000.SN.U 1.5 or it won't work. It'll just keep throwing an error when you try.

My bike came with a later version so I had to purchase another from GreenBikeKit.

 

[il Munduato]

Thanks... Good to know!
Not that I plan on replacing rotors but both of my motors now have that model number and a production date of mid August 2022.
So does the new motor being delivered from GBK with a production date of May 2024

What was the date on the non_compatible controller?

 

[MartsEbike]

Thanks... Good to know!
Not that I plan on replacing rotors but both of my motors now have that model number and a production date of mid August 2022.
So does the new motor being delivered from GBK with a production date of May 2024

What was the date on the non_compatible controller?

My motor is around 3 years older than yours! (doesn't time fly!) My bike was delivered Jan 2021, it was built during 2020. The motor Aug 2020!

Hopefully yours won't have the same issues! The 2024 model should definitely have "quiet gears" pre-installed too.

 

[DDBB]

My ultra is no louder than the Yamaha PW motor on my Haibike, maybe even quieter

 

[il Munduato]

My motor is around 3 years older than yours! (doesn't time fly!) My bike was delivered Jan 2021, it was built during 2020. The motor Aug 2020!

Hopefully yours won't have the same issues! The 2024 model should definitely have "quiet gears" pre-installed too.

I confirmed that it does in fact have the quiet gears with GBK at the time of the order.
I believe all 3rd quarter 2023 and beyond should be quiet gears.

My ultra is no louder than the Yamaha PW motor on my Haibike, maybe even quieter

Whats the letter in the middle to end of the serial number and the following digits?
Z = 2025
Y = 2024
X = 2023 . . . etc...

 

[MartsEbike]

My ultra is no louder than the Yamaha PW motor on my Haibike, maybe even quieter

That sounds promising! Your bike is new too so chances are it already has the upgraded "quiet gears"...

The lack of grease was a common complaint as well so I hope they've addressed that. Some have mention their motors grease seemed to be ok!

But if it was me. I'd still double check it!