MTFCA Forum

As not to steal the other post about ring gear screws, I decided to make my own. As I said in the other post my ring gear has been replaced and the new screws did not want to stay completely tight. They were tightened up, and we used the KR Wilson gauge to make sure they were all the same height. When I went back the next weekend to work on the car a few of them had become loose. We tightened and gapped again, and added Loctite to both ends. Should we have done that? If not what should I do? Now they do not move.

Paragraph 317. Last sentence.
Remember the old saying “ All else fails, Read the manual “

It should be named “Everything you ever wanted to know about a Model T but we’re afraid to ask”.

1925 Touring wrote: ↑

Wed Feb 21, 2024 1:37 pm

As not to steal the other post about ring gear screws, I decided to make my own. As I said in the other post my ring gear has been replaced and the new screws did not want to stay completely tight. They were tightened up, and we used the KR Wilson gauge to make sure they were all the same height. When I went back the next weekend to work on the car a few of them had become loose. We tightened and gapped again, and added Loctite to both ends. Should we have done that? If not what should I do? Now they do not move.

Have you matched the correct screws with the ring gear being used. Can't tell what your using original or repro by "replaced ring gear" & "new screws"
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https://www.modeltford.com/item/3278RE.aspx
Special threaded (1/4 - 24) brass screws used to hold the magnets and flywheel ring gear. DO NOT USE OLD SCREWS unless there is enough stock to peen over ends. These screws are to be used with non-original, reproduction ring gears only 3268.
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https://www.modeltford.com/item/3278.aspx
Magnet clamp screw with special thread, solid brass. Holds flywheel ring gear and magnets in place. Sold each. #14 x 24 (16 required per car.) DO NOT USE OLD SCREWS unless there is enough length to peen over ends. For Original Ring Gears Only, Not Reproduction Gears

You are installing a new ring gear(with the wrong threads of 1/4-24= .250 dia.) With the corresponding incorrect new screws?
Correct threaded screws (14-24 = .234 dia.) are still available. Dont use them in the CURRENT new ring gear.

Why do they not tighten? Are the keepers new repop?
Non matching countersink angles? Burr or high spot on the plates?
Is it as simple as not tightening the screws enough?

I use an impact driver for the final set. The driver must fit the screw slot very well.
After all the screws are tight, I set the protruding ends as ford did with a multi spiked tool & check for tightness again.

A little mistake in the process can be disastrous to your motor.

Adding to what John said above. Buy a 3/8 square drive to flat blade screwdriver bit ( Proto makes them- PN 5240).

Here is on on e-bay:
https://www.ebay.com/itm/134767775875?c ... 6754227a01


Use that to tighten your screws- either with a ratchet or impact driver. Don't try to do a decent job with an old worn out screwdriver as it will only chowder the screw slot. When you have the screw tight, stake the tip of the screw where it protrudes from the ring gear. I use a rounded over cold chisel for this step and prefer to swage the screw tip sideways rather than in an axial direction toward the slotted end, as i feel that tends to reduce the tension in the screw.

The ring gear is brand new, and so are the screws. They are difderent threads than the old ring gear and screws.
We 'waffled' over the ends of the protruding screws with a waffle tool on an air hammer.

There's no need for anything as severe as an air hammer. It's possible you drove the screws back out of the threaded holes by distorting the threads and causing them to become loose.

The problem is there is about .003 difference between the obsolete #14 and 1/4th inch screws and they both have 24 threads per inch.

An earlier thread claimed the 14 did not translate to Chinese and they thought the / was left out by an American mistake.

Both sizes are available, but you have to know what you need.

Also, care as noted to use the modern repro 1/4" x 24 brass screws for new repro ring gears.

Original ring gear and brass screw threads are obsolete #14 - 24.

My experience was bad with loose magnet clamps hitting the field coils, no fun, had to replace all the screws. Builder didn't know the new ring gears are made with 1/4" x 24 thread, and used NOS original brass screws in the obsolete thread form....you can see the result, the screw fit, but soon got loose, likely too by smacking the ends of the brass screws, so they readily de-formed as they weren't a match to the new ring gear.

J1MGOLDEN wrote: ↑

Thu Feb 22, 2024 3:18 pm

The problem is there is about .003 difference between the obsolete #14 and 1/4th inch screws and they both have 24 threads per inch.

An earlier thread claimed the 14 did not translate to Chinese and they thought the / was left out by an American mistake.

Both sizes are available, but you have to know what you need.

No, its .015".
You are installing a new ring gear(with the wrong threads of 1/4-24= .250 dia.) With the corresponding incorrect new screws?
Correct threaded screws (14-24 = .234 dia.) are still available. Dont use them in the CURRENT new ring gear.

speedytinc wrote: ↑

Thu Feb 22, 2024 3:37 pm

J1MGOLDEN wrote: ↑

Thu Feb 22, 2024 3:18 pm

The problem is there is about .003 difference between the obsolete #14 and 1/4th inch screws and they both have 24 threads per inch.

An earlier thread claimed the 14 did not translate to Chinese and they thought the / was left out by an American mistake.

Both sizes are available, but you have to know what you need.

No, its .015".
You are installing a new ring gear(with the wrong threads of 1/4-24= .250 dia.) With the corresponding incorrect new screws?
Correct threaded screws (14-24 = .234 dia.) are still available. Dont use them in the CURRENT new ring gear.

14-24 is .242 dia. (Measuring 5 or 6 taps, I found diameters ranging from .2435 - .245)
1/4-24 is .250 dia.

https://pages.cs.wisc.edu/~bolo/workshop/thread.html

FYI- per the American standard screw thread standard, machine screws start with size 0 and a major diameter of 0.060" . each screw size adds .013" to the major diameter. EX: a # 2 machine screw has a major diameter of .060" + 2*.013"=.086"

A # 14 machine screw has a major diameter of .242. Measuring taps can be a bit problematic / misleading because a tap has to cut some clearance in the root of the internal thread. Hope this helps a bit. The difference between the #14 and 1/4" screws is not much, but it does make a big difference in a critical application like our clamp screws.