Dave, you were obviously working with the engine out of the frame.  Were you pulling the studs with the head already removed (I’m guessing yes).  With the head still on, it doesn’t sound like there is enough stud sticking out to get 1 double nut on there (much less 2-3 nuts).  And getting a box end in there ain’t gunna happen with the head on and motor in the frame.

I’m still going to try to find an M9-1.25P coupling nut 24-40mm long.  I’d like to avoid doing the tap and dye of a suitably different sized coupler.  I don’t have a M9-1.25P tap (I’ve got an M8 and M10 and other sizes, but no 9-iron) so I’d have to buy that (and then probably never use it again).  Adding to my collection of tools that I only needed to use 1 time.

Another possibility, using the double-nut idea would be to find a M9-1.25P nut with a smaller head.  It would butt down on the existing head nut, but allow you to get a deep well socket over it and only grab the bigger M9 head nut underneath.  Worth a look and try.  My concern with this, if such a smaller-headed M9 nut exists, would be its strength given the lesser amount of nut material (thinner from threads to hex outside size).

It is still good to know!  Just making sure I’m wrapping my head around this correctly!  Removing at least the 2 rear studs through the head with the motor still in the frame isn’t going to be fun!  Mike makes everything sound easy!

It relies solely on the friction developed in the threads, similar to the double nut method.  Since it relies on friction, you don't want any oil on the threads of either the stud or the coupling nut, and you want as much thread engagement as possible (more threads = more friction, at least 9mm).  You jam the cap screw down onto the end of the stud, which loads up all the threads.  Make it as tight as you can (within reason).  To remove the stud, I turn the coupling nut.  As previously mentioned, as long as the stud is not set with Loctite or corroded, it will probably work.  If it doesn't, you aren't any worse off.

DragBikeMike wrote on 12/08/23 at 17:02:52:


DBM - I'm guessing the 5/16" drill bit glides right through the 8mm threads and shears the outer threads.  Since 5/16" = 7.94mm and < 8mm.

I've bought the 8mm/24mm long coupler.  I'm waiting for the M9-1.25P tap to arrive from Amazon.  It includes a 7.8mm carbide drill bit.  That bit is really going to glide right thru the 8mm threads (and its probably a bad idea to try to waller it out)???  I do have a 5/16" drill bit if I should use that instead of the 7.8mm.

I'm "struggling to grasp" it there will be deep enough threads after tapping out an 8mm to 9mm with either 5/16" or 7.8mm (both are smaller than 8mm).

And like you, I searched the world over for a 9mm coupler with none to be found.  I have one more custom place I need to check out.

Thanks for the assurance, Mike.  I have a tap handle and bench vise.  I just need my old hands to be steady and not cut crooked sloppy threads.