Tranny and brass magnet screw question

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Model T Ford Forum: Forum 2017: Tranny and brass magnet screw question
Top of pagePrevious messageNext messageBottom of page Link to this message  By Vern (Vieux Carre) on Monday, July 31, 2017 - 11:27 pm:

To get to the point...Do I need to order #14-24 or 1/4-24 brass screws?
When we pulled the engine and transmission, we found this...broken spring, loose metal plate, missing security wire.
Tranny
Pulled the pin and some of it was missing...
spring pin
Cotter pin was missing off adjustment screw...
cotter adjust screw
Adjust screw wasn't in greatest shape...
adjust screw
I ground off the peened ends of the brass screws before trying to remove them. Four survived but what size are they?
screwed screws
Vern


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Bennett - Australia on Tuesday, August 01, 2017 - 12:22 am:

Vern, if you have a Ford ring gear the bolts are a special size. The reproduction ring gears use a standard thread. Both screws are available from the vendors. Just make sure you order the right ones.

Hope this helps.
Allan from down under.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Tuesday, August 01, 2017 - 07:51 am:

The screws for the reproduction ring gears are 1/4-24 (according to Lang's website).

So, find a 1/4-24 screw and see if it threads properly into your ring gear. If it does, order these:

https://www.modeltford.com/item/3278RES.aspx

If the threads on the 1/4-24 screw don't work, then you probably have an original ring gear, in which case you need to order these:

https://www.modeltford.com/item/3278S.aspx


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stephen, South Texas on Tuesday, August 01, 2017 - 09:11 am:

You could just measure the stems of the screws you have. A 1/4" screw will be .250". A #14 screw will be .242". Give or take.


Top of pagePrevious messageNext messageBottom of page Link to this message  By ROBERT BERGSTADT on Tuesday, August 01, 2017 - 09:24 am:

We make the #14-24 screws for the original ring gear, Bob


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chadwick Azevedo on Tuesday, August 01, 2017 - 09:24 am:

Any reason for not just tapping out the ring gear threads to 1/4"?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Tuesday, August 01, 2017 - 09:43 am:

Ring gear is hardened, and the original thread is so close to the repro 1/4" that re-tapping IMO wouldn't be practical. You want those brass screws holding down the magnet keepers and magnets to be real tight thread.

IMO, replace that old Ford ring gear with a new repro and use the new repro brass screws. Reuse of used Ford original brass screws isn't frugal, as it could cause busted engine due to fatigue on those old brass screws!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stephen, South Texas on Tuesday, August 01, 2017 - 09:43 am:

No reason except you taint the gene pool. :-)

And it could remain that way for all eternity.


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Menzies on Tuesday, August 01, 2017 - 10:37 am:

I question if the threads were ever #14, the original drawings were indicated as 1-4" x 24 which was a draftperson's way of indicating 1/4". If it was a #14 screw there would not be no "-" between the 1 and the 4. If you have a ring gear on your flywheel surly they were not #14 screws.

If #14 screws were ever made it had to be very early production.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Larry Smith, Lomita, California on Tuesday, August 01, 2017 - 11:15 am:

No one should have ever made the incorrect ring gear screws. It has caused a lot of confusion.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Vern (Vieux Carre) on Tuesday, August 01, 2017 - 11:17 am:

Ok, thanks guys,
I went to two vendors of hardware and neither had #14-24 nor 1/4-24 screws of any type so that I could try one. 1/4 comes as 20 UNC or 28 UNF. I could not find "Ford" stamped anywhere on the ring but i did find "120FF". The old screw was measured at .232 at the threads and .213 on the smooth shank. So, I'm going with #14 as the answer for my order.
Vern


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Tuesday, August 01, 2017 - 12:10 pm:

The original Ford #3278 magneto clamp screw was the same from 1911 to 1927. Brass screw (2 25/32" x 24 threads, brass) just as stated in the Parts and Price list.

You use this screw with original ring gears.

When you put on a new repro ring gear, DO NOT use the original screws! Use only the 1/4" x 24 thrd for the new ring gear.

Here is what happens when you put NOS 2 25/32" x 24 thd. original Ford brass screws in a new repro ring gear.



Note the stripped threads.



NOS brass on left, threads are stripped in the new ring gear hole of 1/4"x24. This occurs as you stake the end of the screw, since the thread form is different, it deforms with the hammer of the staking, and make the screw back out and loosens the magnet clamps.

On the right side of photo above is the correct new screw for the new repro ring gears.

I know from experience, as some of the clamps became loose and hit the coil ring. NOS screws were used in a new ring gear, then will thread in and 'seem' to be OK, but they will not work out.




Ford original mag. clamp brass screw print


Top of pagePrevious messageNext messageBottom of page Link to this message  By Vern (Vieux Carre) on Tuesday, August 01, 2017 - 12:35 pm:

I measured a 1/4-20 stainless screw just for kicks and found it to be .247. So, I am a lot more confident that my .232 old screws are indeed #14. Hopefully, these numbers will help the next guy. Order placed and we shall see.
Vern


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Tuesday, August 01, 2017 - 06:41 pm:

Related to topic. The basic "numbered" screw sizes date way back to early standardization efforts. To this day, those standards are commonly used for sizes below the quarter inch (#2, #4, #6, #8, #10). Those are the common "even numbers" used for machine screws. There are also #1, #3, and #5 sizes in machine screws, however, they are generally unusual or special electronic sizes. They also come in sizes smaller than #1, however they are also usually special sizes, and may or may not be standardized.
The standard numbered screws also used to be commonly used larger than the common #10. Machine screws #12, #14, #16, and even a #18 used to be readily available. Numbers 12, 14, and 16, have all been commonly replaced by the USA standard quarter inch, in either fine or coarse thread. Corporate America has basically decided that it is cheaper to use the more common standard than to manufacture and stock four different sizes that are so close in size and strength. On that point, I cannot disagree with the corporate decision. It is a more cost effective approach. Numbers 12 and 14 are slightly smaller than a quarter inch. The #14 is within thousandths of an inch size, and virtually identical in strength, to a more common standard quarter inch.
However, a hundred years ago, they were a commonly used size throughout industry, and still made sense to be used in those days. Ford used several #12 and #14 machine screws in the model T. Most notably in the starter and generator, the Bendix cover, and magneto screws. In today's world, they would all have likely been changed to quarter inch sizes.

Wood and sheet metal screws use a similar size scale. Like machine screws, they include both odd and even sizes. However most of the more common sizes for wood and sheet metal screws are the "odd" numbers.

Humorous (?) side note. The relentless march back toward ignorance. About 30 years ago, I went to the local chain hardware store. Now, this store had for many years had a reputation for knowing their business, and having an amazing amount of things one would no longer expect to find in a local hardware store. But times, they were-a-changing.
I needed a #12 bolt for something. I can't recall now what it was, but it was one of those things that I could not easily substitute a different size into it. I knew (at that time) that they would have actually had that bolt about a year earlier. So, in I went.
I could not find the size I needed. No #12 bolts at all. So I asked the clerk. This kid, (younger than I at the time) then proceeds to tell me that I am nuts. That there is no such thing as a "number 12 screw", and that there has NEVER BEEN such a thing as a number 12 screw, in ANY WAY, SHAPE, or FORM. He then basically said I was an idiot for even thinking of such a thing. Now, I have always tried to be polite. But then again, I usually speak my mind. So I walked off, went to the tap and die department (which was actually a different department), and looked. I then went back into the hardware department, and politely asked the kid to look at something in the tools department. I showed him what I had found. Then I asked him "If there has never been any such thing as a #12 screw or bolt? Tell me why you have taps and dies for #12 and #14 threads?" He went away mad, after telling me that he had never seen any such thing and therefore believed it had never existed.
I don't hate a lot of things. But I do hate stupidity. I certainly haven't seen everything. I know that, and I am still looking. "Ignorance is a fact! Stupid is a choice. Nobody knows everything." (My quote for the day.)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Vern (Vieux Carre) on Tuesday, August 01, 2017 - 07:30 pm:

Wayne, thanks...
I only had 3 of the 4 screws for my Bendix cover last week and they were all dissimilar. In cleaning up the hogshead hole threads, I inadvertently (actually my wife did) tapped them with 1/4. To add insult to injury, we used stainless Phillips head screws because that is what we had lying around. With your post, I better get out the lock-rite.
Vern


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chadwick Azevedo on Tuesday, August 01, 2017 - 08:33 pm:

When I get into the engine on this car and remove the magneto I will do as I did on my first speedster under my grandfathers instruction and retap all the ring gear threads to 1/4. With a tap in the drill it only takes a min or two. Once its done modern bolts go in and get peened.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Bennett - Australia on Wednesday, August 02, 2017 - 12:32 am:

Wayne, your comment that the wood and self tapping screws usually come in odd number sizes piqued my interest. I have laid in a good supply of slot head wood screws as they were superseded by Phillips head varieties. In all my hunting I found few odd number screws. Those that were, were in the small sizes, 3 and 5 mostly. These are the little buggers used to fit upholstery turnbuckles etc. I have just one box of size 7 steel wood screws, and the difference between those and number 8s is neither here nor there when in use. It is easy to see why they rationalised the offering. Did the US go in the other direction?

Allan from down under,


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Menzies on Wednesday, August 02, 2017 - 11:03 am:

If you look closely at the drawings you will see
1-4 not 14. 1-4 means 1/4".


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Doris, AZ on Wednesday, August 02, 2017 - 11:30 am:

1/4-24 external thread external diameter minimum is .2417", maximum .2489” (Machinery’s Handbook) The blueprint specifies .232” to .242” external diameter min. and max. Perhaps a proprietary Ford thread or it is indeed a 14-24.

(Message edited by AzBob on August 02, 2017)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Wednesday, August 02, 2017 - 11:59 am:

An odd size commonly found on Fords was here.


You need a 5-40 nut on top.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stephen, South Texas on Wednesday, August 02, 2017 - 03:06 pm:

The drawing clearly has a pound sign (#) in front of the 14. I see no period or slash between the 1 and 4. Perhaps you have an astigmatism. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem - SE Michigan on Wednesday, August 02, 2017 - 03:08 pm:

14-24

Major Dia.: .242"
Minor Dia.: .188"


1/4-24

Major Dia.: .250"
Minor Dia.: .196"

The original Ford drawing above shows a #14-24 screw.


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