Square knuckle/birf nut - what do you use to take it off?

Joined
Oct 13, 2004
Messages
127
Location
Pismo Beach, San Francisco, Seattle
Looking for some advice on the best tool and potential ways to easily take off the square knuckle inspection nut on top? Mine is a bit caked in won’t easily turn with a wrench.

It’s looking a bit dry and I’m getting occasional light clicking on some turns while accelerating. Figure I’d pump in some moly to buy me time till I replace the birfs and shaft for my regear later this year.

Any advice on the best way or tool to get this off would be awesome.

Thanks in advance.
 
Joined
Nov 9, 2012
Messages
11,565
Location
Olathe, KS, USA
Looking for some advice on the best tool and potential ways to easily take off the square knuckle inspection nut on top? Mine is a bit caked in won’t easily turn with a wrench.

It’s looking a bit dry and I’m getting occasional light clicking on some turns while accelerating. Figure I’d pump in some moly to buy me time till I replace the birfs and shaft for my regear later this year.

Any advice on the best way or tool to get this off would be awesome.

Thanks in advance.
A wrench is what I would use.

An offset combination open end-closed end.

Perhaps an 8 point socket designed specifically for square head plugs.

I'm guessing either 14 mm or 15 mm.

That said, you could also use an open-end adjustable metric wrench if necessary.

I don't think a hammer would be an appropriate tool for this particular application.

However, I do recommend a wire brush be applied first to eliminate all the debris that you will otherwise drop into the hole once removed.
 
Last edited:
Joined
Sep 20, 2019
Messages
128
Location
Colorado
Am I the only one who just uses a 12mm box wrench? Or am I thinking of the wrong plug?

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Joined
Oct 7, 2013
Messages
244
go to homedepot or lowes or amazon and find a pipe plug socket, its got a square hole to fit it. i misplaced my craftsman socket otherwise i'd snap a pic of it

also.... hit it with a wire brush then some pb blaster, let it sit for a little bit, tighten just a hair to break loose any corrosion then remove as normal
 

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