Screw Size

[bjensen64]

okay, trying to get a flywheel off of a 1936 K80. I wanted to use a basic puller using the three screw holes used to secure the Johnson id/cover plate.

What size bolts to use? I have plenty but nothing seems to match. Comparing to the original screws, the thread pitch appears to be 24 and the bolt size 1/4.

A 1/4-24 bolt/screw isn’t something I can find at the local hardware store….

Brooke
Poquoson, VA.

[Alan Pelot]

It would be a 1/4-28 fine or a 10-24 which is 3/16.

[bjensen64]

alanp,

Tried those, 3/16 is too small and 28 thread pitch doesn’t match.

I even took one of the screws to a local bolt/screw specialty shop and they confirmed thread/bolt size but that didn’t help us find a usable bolt.

[RICHARD A. WHITE]

What you will find when tinkering with these ancient relics is that back in the day that thread size WAS common……But no longer… search McMasterCarr or even MSC, and you will find that screw size…

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

[Mumbles]

It’s been a while since this topic has come up but yes, those threads are 24 TPI. Early Fords and Johnsons used this thread size and it’s probably old ASME #14-24 or AS 1/4-24. There’s only 0.008" difference between the two so careful measuring should determine which they are. 1/4-24 thread OD is .250 while #14-24 thread OD is .242.

Taps and dies for each can be found but if you have a friend with a lathe, he should be able to make up a few screws to use with your puller.

[bjensen64]

I was afraid of that, thanks guys.

Found some 5/16-24 on the Master-Carr site….still looking. Maybe I’ll check out the local Fastenal store.

[johnny-infl]

Edit: I misspoke about having some 1/4-24 bolts – – – what I actually have is 1/4-28

[green-thumbs]

Odd size or obsolete fasteners are the rule…remember industry has now gone METRIC.
It is puzzling to find fasteners at hardware store made to inch are made in countries
that are metric standard. It is helpful to have a thread gage or test plate to verify
fasteners. Older taps and dies sometimes pretty cheap at garage sales can be useful
to freshen up threads. Threads and gears have evolved and left many orphans in
the progress to one international standard…which is yet to be achieved.
Louis

[garry-in-michigan]

One of our enterprising machinest members made a heavy steel adaptor ring deeply countersunk for the Johnson #14 x 24 screws with an alternate set of ¼ X 20 threaded holes for his standard puller screws. It takes the place of the Johnson rope sheave and pulls the flywheel with no problems. . . 🙂

[Mumbles]

Doesn’t the K-80 use the stepped flywheel nut which is captured by the rope sheave or cover to aid in removing the flywheel? Many outboards of this era used this system.

---

Attachments:

[Author]

Posts