Tongsheng crank wobble - can I use Loctite?

J

jimat

10 µW
Joined
Feb 2, 2020
Messages
5
Hi

After 3 weeks of use and 350 miles, I've noticed a couple of worrying issues with my Tongsheng mid-motor:

1) The chain ring wobbles +/- 1mm, enough for it to catch on the motor housing and make a scuffing sound
2) The pedals wobble +/- 1mm in/out/up/down

Neither are caused by loose motor mountings - everything is rock solid. I've removed the crank spindle and there seems to be two problems:

There's a lot of lateral play in the sprag clutch bearing (that holds the chain ring);
The bearings that support the crank spindle are a very loose fit on the shaft (the shaft has been polished by the slippage - see photo). I've bought new spindle bearings and sprag clutch :(

Question 1: can I use Loctite 638 to lock the bearings onto the spindle / into the housing to reduce the wobble? Is it OK to get loctite on the woodruff key area between sprag clutch and torque sensor?

Question 2: - is this unit made of cottage cheese or have I just been unlucky? It's only been used for commuting on flat UK roads, not off-road single track or steep gradients

Thanks
Jim
 

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jimat said:
Hi

After 3 weeks of use and 350 miles, I've noticed a couple of worrying issues with my Tongsheng mid-motor:

1) The chain ring wobbles +/- 1mm, enough for it to catch on the motor housing and make a scuffing sound
2) The pedals wobble +/- 1mm in/out/up/down

Neither are caused by loose motor mountings - everything is rock solid. I've removed the crank spindle and there seems to be two problems:

There's a lot of lateral play in the sprag clutch bearing (that holds the chain ring);
The bearings that support the crank spindle are a very loose fit on the shaft (the shaft has been polished by the slippage - see photo). I've bought new spindle bearings and sprag clutch :(

Question 1: can I use Loctite 638 to lock the bearings onto the spindle / into the housing to reduce the wobble? Is it OK to get loctite on the woodruff key area between sprag clutch and torque sensor?

Question 2: - is this unit made of cottage cheese or have I just been unlucky? It's only been used for commuting on flat UK roads, not off-road single track or steep gradients

Thanks
Jim
Click to expand...
You need to install specific washer to reduce that wobble - see on the PSWPower.com, they sell that specific washer.

And don´t forget to install our developed OpenSource firmware to have new, much more powerful TSDZ2 motor!! -- https://github.com/OpenSource-EBike-firmware/TSDZ2_wiki/wiki/
 
Thanks Casainho.

I can see how that might reduce the play in the crank left to right, but not up/down, nor the chain wheel wobble.

I'll definitely be trying the firmware update, so long as I can keep the thing running reliably :thumb:
 
jimat said:
Thanks Casainho.

I can see how that might reduce the play in the crank left to right, but not up/down, nor the chain wheel wobble.

I'll definitely be trying the firmware update, so long as I can keep the thing running reliably :thumb:
Click to expand...

If the freewheel has dimples on it, you might need to tighten it with a wood or rubber hammer and a pike.
https://youtu.be/3XWhIqzxK2c
0:20-0:30
Is what you do, but you don't need the special tool, just a hammer and a pike like the guy has here.
https://youtu.be/DiTzEsx_L3c
3:12-end
 
jimat said:
..... but not up/down,............
Click to expand...
For left/right you can use washers.
For up/down:
You can insert a second bearing behind the dustcap (arrow).
On the other side (circle) you can fill the space between axle with 0.07mm metal sheet (like from a cheap feeler gauge).
I know steel is not the best material if the axle is like "cheese", better is to use some softer material if possible.

Edit:
On the tsdz2 safeaschuck has done modifications and has illustrated this with pictures
 
Handy - googling for pretty much the exact same symptoms. To check, have you got about this much movement?

https://youtu.be/NjgzVGr5JRI

I've gone less distance than you, but definitely more up down and with full shopping loads...
 
Hi Darkerside,

Yes, exact same amount of movement as your youtube video. I'm 99% sure it is caused by a loose sprag clutch bearing. There was noticeable lateral play in mine.

I bought a new CSK-30P bearing from here: www.kugellager-panta.de. Cost about £25 delivered. Bearing feels much tighter than the 'Chinesium' version it replaces.

I will have it fitted on the bike tomorrow, so will report back then

Cheers
Jim
 
Thanks for the replies.

So is Loctite a definite 'NO' ?

Is this because of concerns about getting the crank spindle apart in the future? I've read that heat, from an electric heat gun, is enough to soften loctite for tear-down. Would that amount of heat risk damage to the torque sensor? Or would the motor kick out enough heat to soften the loctite?

Cheers
Jim
 
Hi

Just to update this thread:

Reduced the chain ring wobble by fitting a new sprag clutch. There's still a small amount of lateral play, but much better and not scuffing on casing.

Reduced the pedal / crank wobble as follows:
At the drive end of the spindle: I was able to slide a piece of 0.1mm feeler gauge between the spindle and the torque sensor.
At the non drive end of the spindle: I fitted an extra bearing behind the dust cap; was able to slide a piece of 0.04mm feeler gauge between spindle and outer bearing; and used loctite 638 on both bearings, but only between spindle and inner race.

The SKF bearings I used were a tighter fit in the bottom bracket tube, so I needed to use a 19mm deep wall socket to tap them into place. I didnt use loctite on the outer surface (between bearing and bottom bracket tube), so should still be able to tap the whole spindle out from the drive side if I need to dismantle in the future.

Put 50km on it yesterday and it is was fine

Cheers
Jim
 
Hi Jim

After just 150km(!!!) I have the same problem and just ordered the parts to do the same as you have. Some months have passed since you fixed it and I was just wondering if the problems are still solved.

Is it btw possible to change the bearing on the torque side also? It has some slack on that side also .. If so do you know what type it is?
I'm just thinking it would be good to have a quality one installed instead of this chinese quality...
 
Be aware guys that the sprag clutch in the freewheel mode will have a lot more movement unloaded than when it’s in the locked mode. It may not seem engineering wise great, but that bearing unlocked and with the lever arm length of the crank, will accentuate any movement.

We have found that by putting a bearing in the spyder will help with both movement but more importantly water ingress prevention. We are finding that single row bearings are not surviving in that position in an English muddy winter. We may need to fit a more expensive double row with better protection.
 
I too have a small lateral wobble.

Tried the washer replacement route; only a slight reduction. Does anyone have part numbers or a supplier they are happy with for bearings for the United States market? I'm interested in replacing both sides or adding a second one on non-drive side as described below.

Or, id someone has figured out the exact sizes maybe they could post the measurements?

Thanks
 
Also, looking at https://usbearingsandbelts.com/collections/bearings there are a lot of bearing types...so type and size would be great information too if anyone has is...

I think I've come up with a nick name for the TSDZ2...I'm going to call it "Dizzy"...which is what I will be by the time I am done learning all its idiosyncrasies.

CKBuijs said:
I too have a small lateral wobble.

Tried the washer replacement route; only a slight reduction. Does anyone have part numbers or a supplier they are happy with for bearings for the United States market? I'm interested in replacing both sides or adding a second one on non-drive side as described below.

Or, id someone has figured out the exact sizes maybe they could post the measurements?

Thanks
Click to expand...
 
CKBuijs said:
.... there are a lot of bearing types...so type and size would be great information too if anyone has is...
....
Click to expand...
file.php


To add extra bearings on the spindle, as Waynemarlow mentioned, I have written a small "how to" with a few pictures here for the spider side.
Pictures of mounting one (or two) bearing(s) on the non-drive side you find here

If you not replace the oilseal, the outer bearings must be a waterproof Enduro type.
Eventually fixed on the spindle with medium strenght 641 retaining compound and/or rubber ring between crank and inner bearing.

The size of the bearings is 15x28x7mm. (6902)
A double row bearing is a bit wider 15x28x10mm (3902)

The wobble will not dissapear, but the spindle is supported on more places.
 
Hey all! I think I have what's being described. I have a little up and down wiggle on my motor. I'm not sure if I just didn't tighten the M33 nut enough. I noticed I'm getting some squeaking from it too when there's more torque. If it's a smooth flat surface I won't hear any squeaking. I guess the first thing I should do is take the cranks off and retighten the M33 nut that came with the kit. I feel like I just need to buy a crank removal tool at this point. I've been making a lot of trips to my LBS lately :lol:
 
Hello
Thank you very much for such valuable information. Do you know of any supplier or private seller that machines a bottom bracket with good material? Someone said to weld the bottom bracket to the Torque sensor shaft, where the splines are. If it were all a welded part, could it be disassembled? I have this oscillation problem and I prepare for the worst. I think it goes further. Perhaps a new part or a new motor, of current manufacture, has solved the problem definitively?
Thank you
 
Hi All,
I was wondering if anyone could tell me where to source the spindle from. I have a TSDZ3 middle motor on an eMTB from ALDI in Australia. Unfortunately the support company TEMPO does not seem to be able to organise this spare part for me. Also I am assuming that the spindle for the TSDZ3 is the same as for the TSDZ2?!
Thxs!
 

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KCA said:
Hi All,
I was wondering if anyone could tell me where to source the spindle from. I have a TSDZ3 middle motor on an eMTB from ALDI in Australia. Unfortunately the support company TEMPO does not seem to be able to organise this spare part for me. Also I am assuming that the spindle for the TSDZ3 is the same as for the TSDZ2?!
Thxs!
Click to expand...
If the Tsdz3 is equal to Tsdz2, there should be no problem to use the same spindle.
Some shops do sell the longer (100/120mm) spindle as seperate part, but for stock you must buy a complete set incl. torquesensor.
Ofcourse you can remove the spindle of it as a replacement.

FYI
I see you use the Tsdz3 for an eMTB. Often does that mean too, jumping when standing on the pedals.
If the spindle is broken it will be mostly on the thinner and weaker circlip grooves.

I have write the next a lot of times. As you see on your picture there is just one bearing
By adding an extra 6902 bearing on the other side of that groove you have support on both sides of it, what could help against breakage. The same you do on the othere side of the spindle.
So in total two, relative cheap, extra bearings, placed in a half hour can save you more work and costs.
 
Last edited:
Elinx said:
If the Tsdz3 is equal to Tsdz2, there should be no problem to use the same spindle.
Some shops do sell the longer (100/120mm) spindle as seperate part, but for stock you must buy a complete set incl. torquesensor.
Ofcourse you can remove the spindle of it as a replacement.

FYI
I see you use the Tsdz3 for an eMTB. Often does that mean too, jumping when standing on the pedals.
If the spindle is broken it will be mostly on the thinner and weaker circlip grooves.

I have write the next a lot of times. As you see on your picture there is just one bearing
By adding an extra 6902 bearing on the other side of that groove you have support on both sides of it, what could help against breakage. The same you do on the othere side of the spindle.
So in total two, relative cheap, extra bearings, placed in a half hour can save you more work and costs.
Click to expand...
Thanks Elinx - the spindle is not broken but it is slightly bent and one of the bearings is not sitting tight enough on the spindle. What I am observing when riding the bike uphill is a noise when pushing down the left pedal.
Will see if I can order a new one and fit two bearings instead of one on each side.
 
scrolltonowhere said:
I feel like I just need to buy a crank removal tool at this point. I've been making a lot of trips to my LBS lately :lol:
Click to expand...

Depends if the lbs charges you for it.. I mean, it's a real quick job and the needed tool costs you 15 bucks for a decent one.
Elinx said:
So in total two, relative cheap, extra bearings, placed in a half hour can save you more work and costs.
Click to expand...
It's almost criminal to require your buyers to take these steps to get the most out of their purchase, then again that's why it's affordable.

And I'm not complaining so far, did 55km today trying to clear my head a bit in the wind.. wouldn't have gone out with the assistance :)

Court day tomorrow, head not in the right place.
 
marvin78 said:
....

It's almost criminal to require your buyers to take these steps to get the most out of their purchase, then again that's why it's affordable.
....
Click to expand...
You don't need extra bearings and heatconductive materials, if you use your bike for short citytrips.
For eMTB use and/or running a long time at max. Power it are easy and relative cheap "to do" additions
 
As noted I wasn't complaining. Especially since these upgrades still less expensive as an equally performing torque assist mid drive.

I could have spend a little more for bbs02 and have something of higher quality and faster / more power. But I don't want pas, switching to my cadence based hub drive makes me appreciate that choice every single time.
 
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