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  1. #1
    CB750 New Member Anna's Avatar
    Join Date
    Oct 2017
    Washington DC

    How to make your own clutch lock nut wrench (and save $200)

    I am rebuilding the engine of a 1992 CB750 and came across an odd lock nut when I got to the clutch.
    It's not a hex nut, it's round with four slots (see photo below).
    You can only remove it with a special 4-pin socket (OEM part number: 07716-0020203) that Honda is happy to sell you for $60 .

    What's particularly annoying is that you don't even get to use the socket twice because the OEM replacement nut is a ... wait-for-it hex nut.
    Click image for larger version. 

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    But wait, there is more. In order to keep your clutch from happily spinning along when you try to unscrew the lock nut, you need to have a clutch center holder (OEM part #: 07 JMB-MN50300) that will keep the clutch from rotating while you remove the lock nut. This clutch holder comes at a bargain price of $165.

    I am a big fan of having the right tool for the job, and I love high-quality tools, but paying over $200 to remove *one* nut is highway robbery!
    So here is what I did cost me all of $5 and an hour of my time:

    I dug around in my garage and found two slotted flat steel bars. Angled ones would have probably worked better because they are more rigid but the flimsier flat ones did the trick.
    Using the original clutch center bolts, I bolted the bars to the clutch center like this:
    Click image for larger version. 

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    165 dollars saved!

    Then, I bought a socket with a 34mm (1 5/16 inch) outer diameter. In my case, it ended up being a 15/16 Pittsburgh socket from Harbor Freight but the outer diameter is what's important here.
    I drew a 90 degree cross on a piece of paper and centered the socket on it to mark the four pins.
    Click image for larger version. 

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    The pins should be about 6mm (1/4 inch) wide.

    I dug up my Dremel* tool, some cutting wheels and sanding drums, and mounted it into my bench vice (*well ... the cheap knock-off version ).
    In the slotted parts, the lock nut's outer diameter is 29mm ( 1 1/8 inch). Using the sanding drum on my Dremel tool, I sanded the inner side of the pin marks until the inner diameter of the socket (i.e. the inner distance between two opposing pins) was a smidge over 29mm:
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    Then, I cut the parts between the pins out (about 5mm deep):
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    E voila, I had the exact same socket that Honda is selling for more than 10 times the cost.
    Click image for larger version. 

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    The lock nut needed some convincing so I had to use my impact wrench but it should come off with a regular breaker bar in most cases.
    Click image for larger version. 

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    So many motorcycles, so little space in the garage.

  2. #2
    CB750 Addict Chris in Dorset England's Avatar
    Join Date
    Mar 2017
    Weymouth, Dorset, UK,
    Regarding special tools, almost always there is a cheaper way!

  3. #3
    CB750 Addict Hippie459MN's Avatar
    Join Date
    Jul 2013
    Saint Francis, MN
    $8 on amazon and free 2 days shipping (in the US anyways) if you are a prime member for the right socket for the job. As much Honda stuff as I work on, I just bought the tool. Sadly Honda wants a small fortune for it.

    Awesome job making the tools. I have been down that road many times myself.
    1979 Honda CB750 Chopper

  4. #4
    CB750 Member CocZamudio's Avatar
    Join Date
    Jun 2015
    Boulder, Colorado USA
    Brilliant! Thanks for the great photos and text.
    Its not that we own it. Were just maintaining the asset for future generations. (Hari Kunzru, White Tears)

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