TSDZ2B brake issue: pedals "freewheeling"

[!nFerNo]

Hi everyone

I have a TSDZ2B and I've been having a specific issue for a long while. I haven't been able to ride my bike as often as I used to, but it finally bothered me enough to look on the internet and see if others have this issue and might have fixed it.

I have a bicycle with a rear V-brake. I use the brake handles that came with the motor, which has a cable to the brakes and a cable to the unit. Obviously, when I brake, the motor disengages, which is how it's supposed to work. But, there is a side-effect that I didn't have with my TSDZ2 motor: when I apply the brakes, often the pedals will stop engaging completely. It has me pedalling into thin air, so to speak. Like pedalling backwards, but now in forward motion. Sometimes it will engage after a stopping the rotation a few times, sometimes I have brake and release a few times. I haven't figured out what causes it, or how to "undo" it.

Today I was playing around with it, as I was troubleshooting a loud cracking noise from the motor, and noticed this behaviour happens without the battery. It's not related to the motor "in operation", it seems to be a mechanical something.

Does anyone else have this behaviour on their TSDZ2B?

I tried recording it:

About the loud noise: only seems to happen when applying lots of torque. My wife thought it was the derailleur or the chains that needed some oil, but I was carefully listening for it and it clearly came from the motor. I opened it up, but it was still very clean inside, checked gear and closed it up again. I saw this issue pop up a few times so I'll be reading the forums a bit more for this one.

 

[docw009]

What you're showing is the pedals spinning w/o turning the crank, which cannot turn because the wheel is locked. I have seen that on our TSDZ2B. It has a drive gear that has three separate moving rings. The motor drives the outer ring., The pedals spin the inner ring, The middle ring turns the chain and is driven via two sprag clutches from the outer/inner rings, I am syre that the inner clutch from the pedals is slipping in your bike.


The tried and true fix is a new gear, which you can buy, It cost me about $45 USD in 2023, but I never installed it,

Instead, I tried cleaning/relubing the inner sprag clutch. This works for some owners, Fails afterwards for others. May depend on whether the sprag parts were just dirty or truly worn out, In my case, the motor was fairly new so maybe it was just dirty. I sprayed with brake cleaner. Waited for it to dry. Then re-lubed with 30 wt, Been OK for over two years and several thousand miles,

There is a youtibe video from Tongsheng on replacing the gear. Pretty easy. They use a puller to remove the gear, but it should come out w/o tools. You might not have to pull it off to clean, but doing so helps keeps the solvent from getting to the outer clutch,

 

[!nFerNo]

After releasing the brake, it will often still not engage, even if the wheel isn't locked anymore. Is that what you experienced, and that can be fixed by replacing this gear?

It doesn't really feel like it's slipping. When I brake with the front brake then this issue doesn't occur, and the motor doesn't overcome the friction on the road and "peel out". If it were feedback from a locked wheel that causes it, then it would happen in that situation too. It never happens when standing still (and brakes weren't applied).

Will order this gear, it appears to be somewhere between 40 and 70€.

 

[docw009]

Two YT videos showing the pedals spinning free because of loose clutch. The spin forwards and don;t catch the chain gear.