Nighthawk: Clutch removal – make your own tools
I am rebuilding the engine of my 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. And 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 (whaaaa…?).
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.
Don’t get me wrong, I am glad that Honda came to its senses – but why have the round lock nut in the first place???
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) which will keep the clutch from rotating while you remove the lock nut. This clutch holder comes at a bargain price of $165 (what the what?).
I am a big fan of having the right tool for the job, and I love high-quality tools as much as the next guy, but paying over $200 to remove one freakin’ 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 flimsy flat ones did the trick.
Using the original clutch center bolts, I bolted the bars to the clutch center like this:
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 location of four pins (it’s important to be as exact as possible here). I used a white chalk pen I had lying around but a pencil works as well.
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:
The lock nut needed some convincing so I had to use my impact wrench to get it off but it should come off with a regular breaker bar in most cases.
Why is there a Triumph logo on my engine dolly? Because the Triumph man (my better half) made it for me but had to ruin it before he let me have it, of course.