How to disassemble motor adapter from sprocket/freewheel?

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azad   10 mW

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How to disassemble motor adapter from sprocket/freewheel?

Post by azad » Feb 05 2020 4:09am

Hi,

I have a sprocket with pre-installed adapter for motor shaft. I would like to take apart/disassemble the two (i.e. separate the sprocket/freewheel from the adapter). What is the most suitable way to do that? (already tried putting it in vise but it slips).
sprocket_with_adapter.jpg
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Last edited by azad on Feb 24 2020 2:17am, edited 1 time in total.

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marty   10 MW

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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by marty » Feb 05 2020 12:08pm

Look.
Sheldon Brown / Traditional Thread-on Freewheels
https://www.sheldonbrown.com/freewheels.html
MARTY
Volt Electric Vehicles
http://www.voltev.com

azad   10 mW

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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by azad » Feb 06 2020 9:28am

marty wrote:
Feb 05 2020 12:08pm
Look.
Sheldon Brown / Traditional Thread-on Freewheels
https://www.sheldonbrown.com/freewheels.html
I don't understand!

I am not trying to open a freewheel. I have an "adapter" tightly screwed in the freewheel. In the picture you see one full freewheel with the adapter and one dismantled freewheel with the same adapter (the silver one). it is a motor mount adapter which goes in the motor shaft. I want this to disassemble from the freewheel.

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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by Punx0r » Feb 06 2020 9:52am

I assume you're trying to save the threaded adapter?

Grip remains of freewheel in vice with soft jaws (or blocks of wood) and use a pipe wrench on the collar of the adapter. If you suspect a thread locking compound has been used, first heat the assembly to >100°C.

If that doesnt work you have to carefully cut through the remains of the freewheel (taking care not to cut deep enough to damage the adapter threads), then split it with a sharp chisel.

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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by azad » Feb 24 2020 2:21am

Punx0r wrote:
Feb 06 2020 9:52am
I assume you're trying to save the threaded adapter?

Grip remains of freewheel in vice with soft jaws (or blocks of wood) and use a pipe wrench on the collar of the adapter. If you suspect a thread locking compound has been used, first heat the assembly to >100°C.

If that doesnt work you have to carefully cut through the remains of the freewheel (taking care not to cut deep enough to damage the adapter threads), then split it with a sharp chisel.
There is no sealant as I have bought three until now and when they are new they are free to rotate. After using it with a motor for a while it gets amazingly stuck. The problem is that the freewheel is getting worn out so I need a effective way to disassemble the two in order to replace freewheel repeatedly. Things I have tried:

1. put in vise and used a plier to rotate.
2. heated up in oven and tried to open
3. made a cut on the front and used a screw driver to hit on the cut but it doesn't move.

I wonder why it has stuck so much that I can't get it to move.

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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by Punx0r » Feb 24 2020 3:54am

I guess the dynamic torque from your drive motor is doing it up very tight.

Now you have two opposing slots can cut in the face, can you weld a large nut to a piece of flat steel inserted into both slots and use an impact wrench?

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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by azad » Feb 24 2020 5:40am

Punx0r wrote:
Feb 24 2020 3:54am
I guess the dynamic torque from your drive motor is doing it up very tight.

Now you have two opposing slots can cut in the face, can you weld a large nut to a piece of flat steel inserted into both slots and use an impact wrench?
I don't have a welder and wouldn't want to buy one for an adapter :)

However, I tried another thing, drilled two holes in the adapter, put two screws in them, and then tried to use a screw driver in between them as a lever but screws were so weak that they immediately got bent. Running out of ideas, don't know if there are some strong screws around!
20200224_113617.jpg
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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by Punx0r » Feb 24 2020 8:47am

OK, here is what I would do if you have no welder and how have the drilled holes:

Get a small offcut of steel plate 6,8,10,12mm thick
Drill a 1/2" hole in the centre and file square to take a socket wrench drive
Drill and tap two threads corresponding to the drilled holes in your adapter
Tighten down some shouldered bolts (preferably 10.9 or 12.9) in the plate and cut to length

If the adapter is not too tight may be OK having the bolts/pegs span the recess from the outer adapter face to the inner face (this will cause a large bending force on the pegs). If the pegs bend you will need to add some round spacers to fill the gap - either make a steel disc the correct size with a hole saw or find some washers close enough to the right size.

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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by amberwolf » Feb 24 2020 3:55pm

you still haven't tried the one nearly surefire way to get it off: cut the freewheel itself. you use a dremel or similar, and cut thru the freewheel all the way to the threads. because of the adapter's flange, this will be difficult for the part that intersects it, and you'll have to grind the freewheel's own flange down at that point to avoid damaging the adapter. if possible, don't actually cut into the adapter's threads--the freewheel should be loosened enough just by cutting down until you can see the top of the adapter threads. (or made fragile enough to break it off at that point).


short of that, you could cut the edges of the round outer flange of the adapter itself so that it matches the hexagonal pattern of the largest and longest wrench that could overlap it completely, then use that wrench to take the adapter out of the freewheel, with the freewheel core clamped in a vise.

if the freewheel won't stay clamped, grind *it* to have flat sides, too, for the vise to hold onto.


then when you install the adapter into the next freewheel, make sure you thoroughly grease the threads of freewheel and adapter; this will make it at least a little easier to get it out next time.


judging by the scarring on the adapter, the likely problem with getting it off is that it's such a soft metal it is deforming into the very hard freewheel threads; the grease will help with that but not as much as it would with a hardened metal on both sides.

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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by azad » Feb 26 2020 5:02am

amberwolf wrote:
Feb 24 2020 3:55pm
you still haven't tried the one nearly surefire way to get it off: cut the freewheel itself. you use a dremel or similar, and cut thru the freewheel all the way to the threads. because of the adapter's flange, this will be difficult for the part that intersects it, and you'll have to grind the freewheel's own flange down at that point to avoid damaging the adapter. if possible, don't actually cut into the adapter's threads--the freewheel should be loosened enough just by cutting down until you can see the top of the adapter threads. (or made fragile enough to break it off at that point).


short of that, you could cut the edges of the round outer flange of the adapter itself so that it matches the hexagonal pattern of the largest and longest wrench that could overlap it completely, then use that wrench to take the adapter out of the freewheel, with the freewheel core clamped in a vise.

if the freewheel won't stay clamped, grind *it* to have flat sides, too, for the vise to hold onto.


then when you install the adapter into the next freewheel, make sure you thoroughly grease the threads of freewheel and adapter; this will make it at least a little easier to get it out next time.


judging by the scarring on the adapter, the likely problem with getting it off is that it's such a soft metal it is deforming into the very hard freewheel threads; the grease will help with that but not as much as it would with a hardened metal on both sides.
Thanks! Actually this was much simpler than other ideas and it worked. Not a clean cut though - I'm new to multitool anyway.
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azad   10 mW

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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by azad » Feb 26 2020 5:04am

Punx0r wrote:
Feb 24 2020 8:47am
OK, here is what I would do if you have no welder and how have the drilled holes:

Get a small offcut of steel plate 6,8,10,12mm thick
Drill a 1/2" hole in the centre and file square to take a socket wrench drive
Drill and tap two threads corresponding to the drilled holes in your adapter
Tighten down some shouldered bolts (preferably 10.9 or 12.9) in the plate and cut to length

If the adapter is not too tight may be OK having the bolts/pegs span the recess from the outer adapter face to the inner face (this will cause a large bending force on the pegs). If the pegs bend you will need to add some round spacers to fill the gap - either make a steel disc the correct size with a hole saw or find some washers close enough to the right size.
Got a small steel fastner and tried to drill holes in it. Broke 3-4 drill bits (steel bits HSS). Still couldn't penetrate. cut another one though. maybe try this idea again as well.
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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by Punx0r » Feb 27 2020 3:58am

Oh, I thought you wanted to keep/reuse the adapter! :lol:

If something is too hard to drill (assuming a good quality drill bit) often you can just heat it up to a red heat, let it cool off slowly and it will soften it enough to drill.

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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by amberwolf » Feb 27 2020 4:38am

so did i. that's why i described how to cut the defective freewheel off, rather than how to damage and mangle the adapter to where it may not be able to keep the freewheel on the motor shaft. :(

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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by azad » Feb 29 2020 7:43am

Although I disassembled/cut the freewheel out but I have another problem now. The adapter doesn't go all the way into the freewheel. It goes 1/4th in the freewheel and then it locks down. Why is that? Are threads uneven in the freewheel (i.e. get tighter as you go inside it)? Freewheel goes into the old one perfectly fine. (BTW it is a flipflop wheel)
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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by Punx0r » Mar 03 2020 4:22am

If the new freewheel is a different model to the old one then the thread type might be different, Unfortunately freewheels can have a number of similar, but incompatible threads:

https://www.sheldonbrown.com/freewheels.html

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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by azad » Mar 04 2020 6:07am

Bought another one. This one is from China (like the adapter). However, the adapter refuses to go into this one as well.

Aren't threads standard for bicycle hub?
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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by john61ct » Mar 04 2020 3:27pm

From my notes:

Two sizes of thread for freewheel

1. English standard thread, B 1.375*24G,
aka 1.37" x 24 tpi , e.g. Ditca freewheel

2. Metric standard thread M35*1

e.g. older QS 1/2*1/8*16T, 1/2*1/8*18T
and 1/2*1/8*20T

QS told me moving forward they will use the English threading.

Also French bikes from the 70's apparently were a third "standard"?

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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by Punx0r » Mar 05 2020 3:39am

They're all listed in the link I posted above

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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by azad » Mar 07 2020 11:47pm

Sadly there is no listing on neither the selling website or on the packaging about the size of threading ( just the statement that it is for a standard freewheel hub)

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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by Hickbeard » Mar 08 2020 4:41pm

You'll need a thread gauge to measure the threads and see if there the same.

Sent from my CLT-L09 using Tapatalk



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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by Punx0r » Mar 10 2020 4:03am

Or a pair of digital or vernier calipers and a good eye

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Re: How to disassemble motor adapter from sprocket/freewheel?

Post by azad » Mar 25 2020 2:52am

It is a bit tricky to measure but I tried to measure it with vernier caliper. It seems it has 27/28TPI if that is possible?! It has total 14 threads in a 13mm (or 11threads in 10mm) which makes it roughly to 27/28 threads per inch. I'm not sure for what kind of freewheel is it for. It came with a chinese one that fitted nicely but I can't import it anymore.

I have also tried to forcefully screw the adapter on the freewheel threads. It now screws 3/4th into the freewheel easily but last 4 threads are too tight. Any idea if that is possible to screw it all the way?
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