Johnson A-80 flywheel puller bolt size?

[Buccaneer]

Just started working on a 1936 Johnson A-80.
I’m trying to find the right size bolts to pull
the flywheel. The short brass bolts that were
in the holes that holds on the rope pulley
are 24 tpi thread. They’re bigger 12-24
and less than 1/4" bolts, which I don’t
think comes in 24 tpi anyway.
The bolt OD seems to be 15/64".
I can’t find any such critter in any charts.
I don’t think this is the type of set-up
where you can leave the rope pulley on
and back the flywheel nut against it, popping
the flywheel loose, but I’d rather not risk
breaking the rope pulley. Doesn’t look like it’s
been off since put on in 1936 😯
Of course, there’s always the nut and a big
hammer approach, but also would like to try
the puller first!
Thanks!

Prepare to be boarded!

[RICHARD A. WHITE]

Those would be 14-24…. old school threads…..really old school, edited as I realized AFTER my post I typed the wrong number…as I had just done some 12-24 threading…. ughh sorry

http://www.richardsoutboardtools.com
classicomctools@gmail.com

[david-bartlett]

Buc,

I found a metric size that will work for that.

6mm X 1.0. Not a perfect fit but worked for me me.

Hope this helps.

[Buccaneer]

Thanks for the replies. Richard, I edited my post,
but pretty sure I meant to say the bolts are larger than 12-24,
not 10-24, but I’ll recheck tomorrow.
Good to know there’s a metric option available.
I think they’d have to be 2-1/2 to 3" long to work
with my puller.

Update: I just check my note from the garage.
The flywheel bolt size that held the rope pulley
on were 15/64" according to my drill size gauge.
15/64" = .234
A 12-24 bolt diameter is .216 according to the Net.
My 12-24 tap was too loose in the flywheel holes,
which jives with the info above.
Looks like 6mm is the same as 15/64", and if I understand
metric thread pitch of "1", that would be about 25 tpi pitch
instead of 24?

Prepare to be boarded!

[david-bartlett]

6mm = 0.236". Pretty close. Thread pitch is a bit off, but you can go in at least 3/8" before it will bind.

[garry-in-michigan]

An old Johnson dealer I knew (George Cheatem) had a large ring that took the place of the rope sheave. It was countersunk for the johnson’s #12 X 24 screws and tapped in between for standard quarter twenty screws. It allowed him to use the standard flywheel puller on the antique Johnsons with little danger of damage to the old impossible to find #12 screws. . . 🙂

[david-bartlett]

quote Garry in Tampa:

An old Johnson dealer I knew (George Cheatem) had a large ring that took the place of the rope sheave. It was countersunk for the johnson’s #12 X 24 screws and tapped in between for standard quarter twenty screws. It allowed him to use the standard flywheel puller on the antique Johnsons with little danger of damage to the old impossible to find #12 screws. . . 🙂

Garry,

That is a great solution!

[Buccaneer]

Garry, that’s an interesting idea. If I can’t find long enough bolts
in the "one dog" town nearby, I’ll make a puller plate as you
describe and use my long 1/4 x 20 puller bolts.
Thanks.

Prepare to be boarded!

[Mumbles]

On the early motors, Johnson used 14-24 machine screws to hold the rope sheaves on. With a major diameter of 0.242", they are slightly smaller than 1/4" and larger than a #12 machine screw. Since this size was pretty much obsolete before most of us were born, you won’t find them at your corner hardware store today. Taps and dyes of this size are available from specialty tool suppliers but if you don’t want to spend the coin, it might be time to gear up the old lathe to make the screws and and cut the thread.

[amuller]

I’m thinking maybe you are encountering No. 14 x 24 screws. This is not a common size but they do, or did, exist. I think the major diameter of these is around .242. (Just like Mumbles already said!)

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