Help! Tool for removing SHIMANO MF-HG20 cogs

[Bob Fuji]

Hello there,

I'm trying to clean my Shimano MF-HG20 freewheel, and want to disassemble the cogs. But I found there is a lock ring that seems need a special tool to remove it. Could you please teach me what the tool's name is?

It is in 46mm diameter and has 8 notches on it. The notches are semicircle.


   

Thank you.

[ReapThaWhirlwind]

I do believe that is called a Lockring Spanner Wrench.

There are more than a few types.

Have you tried using a regular spanner wrench and a chain whip yet?

[Bob Fuji]

(07-30-2021, 01:17 PM)ReapThaWhirlwind Wrote:  I do believe that is called a Lockring Spanner Wrench.

There are more than a few types.

Have you tried using a regular spanner wrench and a chain whip yet?

Thank you for your information.

I will try to find a Lockring Spanner Wrench that fits the notches. I have a Bottom Bracket Lockring Wrench for crank lockring and I tried to use it with a chain whip, but because the notches are not square that makes the wrench can not hold the notch firmly.

[ReapThaWhirlwind]

Note that the specific tool for that cassette however may not be acquirable by natural means.

It could have been a manufacturing side exclusive tool only Shimano has.

You could go to a Machine Shop/Tool & Die, and one of the engineers could possibly make you a tool to remove it.

You're looking to spend a pretty penny though for their service.

[JerrySTL]

A Park Tool LRT-3 Lockring Tool 'might' work.

However a freewheel is rather cheap. For example you can get a MF-TZ500-6 or MF-TZ20-6 6-speed freewheel for under $30.

If you just want it cleaner, spray between the gears with something like WD-40 and 'floss' between the gears with a thin rag.