MTFCA Forum

Herewith is the version 2.3 of the Bolt chart updated 7 August 2023. Hope it is of use and interest.

I have attached updates of 3 files:

1) EXCEL spreadsheet with the updated chart (first sheet) AND the original inputs (following sheets). The updated chart is the more accurate.

2) PDF Sorted by Part Number then 'Assembly Area'

3) PDF Sorted by 'Assembly Area' then Part Number

(The Excel and 2 PDFs are identical in content)



(Charts can be found in a section of the Gallery: app.php/gallery/album/195 in JPEG format. There are 4 files each for sorting by Assembly Area and by Part Number.)

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Adrian: Bendix cover screw description (p/n 5059) is 14-24, not 1/4-24, these are NOT interchangeable as I noted earlier. I respectfully suggest the notes entry should reflect this fact, the #14 screw diameter is 0.242, not 15/64 (0.2344"). Again, not a criticism of your work, but I feel getting it right now will save someone frustration down the road. Thanks again for your work on this, and thanks for getting it on the web site. jb

The bolts holding the 1909 rear axle halves together are incorrect. There are five on one size and two slightly longer. Tomorrow I will take a couple of pictures and measure the bolts. I will also find from the encyclopedia when the change from the pressed steel to casting occurred.

Thanks guys, I will do an update

Keep the information coming.

I went out to the shop this morning and measured the length of the bolts on the differential housing on my October 1909 Model T.
The two either side of the spool are 2” long while the remaining five are 5/8” long.
According to page 446 of the Encyclopedia the change from the pressed axle halves to cast occurred in July 1911. At that time the bolts probably all became the same length which on the 1914 are 1 5/16” long.

Unfortunately this does not explain all the part numbers. The 1 5/16” appear to be 2503E but I don’t know the length of the suffix from A thru D. None of the lengths in the current spread sheet correspond exactly to the two bolts I measured. The 2503A at 9/16 is close to my five short bolts and the 2503D at 1 7/8” is close to the two remaining. I wonder where the suffix B&C where used.

Observation.
I find it interesting that when Ford went to new castings, probably under the direction of Sorenson who was a brilliant manufacturing Engineer, he made special efforts to reduce the number of different lengths of bolts to a minimum. This is especially noticeable on the block when extra metal has been added to make all the block to pan bolts are getting same length. So when they went to the cast rear axle halves, he would have ensured all seven bolts were the same length.

Tony

Those bolt lengths with those 2503 suffix part numbers are in my copy Sept 1912 Price List of Parts. Gives # per car as same in the my changes to the new spreadsheet.

What isn’t associated with these part #’s is year(s) of use. Obviously the short bolts needed for pressed steel clam shells, 5 ea. The 2 ea. longer are for the ends.

As for years of use, my guess is they cover mid year or overlap year for each change in the housing designs.

The A,B,C,D are all as used to Sept 1912 as they are in that Price and Parts List.

The latest bolt is of course the 2503E is the 1 5/16” length for the last style housing center 1915 (or late 1914) to 1927.

Here is a theory about suffix B and C bolts. Mine appears to use five -A short bolts and two -D bolts in my Oct 1909 vehicle. During the first year there were several changes to the rear axle associated with the backing plate. It could be that the area either side of the spool with originally thinner and the material thickness increased during the year when the backing plate changes were made but were not noted in the factory letters. This would explain why the -B -C and -D increased in length over the first year.
If this is correct then the chart would look something like this:

2503A. 9/16 5 1909-1911
2503B. 25/32 2. 1909
2503C. 1 1/16 2. 1909
2593D. 1 15/16 2 1909-1911

Just my thoughts.

Tony

Thanks. I tried to tie the bolt lengths for those housing bolts to the design changes of the pumpkin.

The '09-'10 went through several changes, so I think some of the suffix parts are related to those changes, just don't know which!

Per Bruces's C-D, quotes from the Encyclopedia in italics, these are some of them:


1909 October 1909). Babbitt inner axle bearings. Smooth brake backing plates. Pressed-steel housing with no rivets and no reinforcements.

Early 1910 Six-rivet style. Non-tapered axles. Roller inner axle (after 12,000, October 1909) and pinion (after 18,000, March 1910) bearings.

Later 1910. Later 1910 housings had reinforcing washers around the flange bolt holes, and still later, a ring brazed around center section. By 1911 two such rings were used, one on each half, inside the housing, making the center seam much thicker.

So if the center were thicker by the brazed washers to give more strength, then longer bolts, the # 5 around, plus the 2 real long ones.

1910-1911 style continued until July 13, 1911 when new “1912” rear axle (12-rivet, clamshell design with cast center section) appeared.

Seems the new cast center would need longer bolts, and maybe this is when the 7 set of bolts was used, as all could be the same length.

1913-1914 Introduced in about October 1912. Larger cast center section, similar in shape to later types, but with the axle tubes flared and riveted to the center section.

and finally the normal later cast center, which was same pumpkin flange to the end of production, but axle feature did differ, but not the set of 7 bolts length used.

1915-1919- all the way to 1927 (at least the center flange thickness). New “standard” design adopted about March 1915. Tubular axle housings inserted into center section.