***1909-1920 Transmission Brake Drum Assembly***

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Model T Ford Forum: Forum 2018: ***1909-1920 Transmission Brake Drum Assembly***
Top of pagePrevious messageNext messageBottom of page Link to this message  By Martin Vowell, Sylmar, CA on Friday, April 06, 2018 - 02:48 am:

Ok, Larry Smith told me to "do your research" and I did. I looked over every Ford factory drawing I had on this subject and found that the transmission is one big slop-over-fest. Then I consulted Bruce's works (the Encyclopedia and his Parts Catalogs) and this left me more confused than just studying the bloody factory drawings.

Basically what it is, is this...the overall design of the "Transmission Brake Drum Assembly" doesn't change significantly enough on the outside to warrant making a bunch of different drawings (the rear bushing, is the only change)...on the inside (where the clutch disks go) it changes a lot. When I make the transmission to flywheel drawing I'll address it then. But for now, I think this works.

Those bloody bushings are all over the map as to what was used when and on which model year and like the note says, "sometime between 1916 and 1920" the flange bushing got dumped in favor of just using two 3320C (T712) bushings in conjunction with 3 steel thrust washers. But prior to that, there was a time (approx, 1912 - 1920) where the flange bushing was used. That was the replacement for the 3320 (T754) and the Thrust Bearing (washer) 3320-1/2 (T761). That thrust bearing was briefly used between 1909 - 1911. But the early 1909, used 3320 (T712) had the same bushing arrangement as the later (same bushing in both ends, and no flange), the only difference between them is that the early bushing was a bit longer and they were used between 1909 - 1913. I found this out by backtracking the revision lists, to see what was changed and when.

The "T numbers" are Ford engineering print numbers...nobody seems to sell an early brake drum nor do they seem to manufacture one either, so I used the engineering drawing part number for these parts, because the part number 3311 is for the whole assembly (Ford didn't sell just the drum either or at least it doesn't show up in those catalogs anywhere). I also included the engineering part number on all the parts, because I was primarily working from Ford drawings, and I actually had to look up the vendor part numbers in Bruce's catalog book. Like all engineering drawings, when a change comes up, they just scrub out the old parts and or notes and redraw in the new configuration...so getting an actual 1909 brake drum drawing is sort of hard. What I worked from was the 1914 Transmission Brake Drum drawings (T750) and traced back the revision lists from those drawings....fun never quits guys. :-)



As always, if you can think of something I've forgotten and or missed, please let me know. Meanwhile I'll slog through the Trans to Flywheel drawing...I figure I should probably do these in sets, because one pretty much supports the other.


Top of pagePrevious messageNext messageBottom of page Link to this message  By George n LakeOzark,Missourah on Friday, April 06, 2018 - 01:50 pm:

Way to go Mart, you rock !!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Martin Vowell, Sylmar, CA on Friday, April 06, 2018 - 03:12 pm:

This is a cross section of a 1914 Transmission Brake Drum, notice that there is no flange on the bushing? In fact the rear bushing is recessed into the shaft by 1/64th of an inch...I suppose this is to allow oil to seep in and coat the transmission shaft.



The other difference with the 1914 drum is the placement of the oil slots...instead of being half way between the clutch lugs, they are right over them...allowing more oil to lubricate the lugs.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Martin Vowell, Sylmar, CA on Sunday, April 08, 2018 - 03:35 am:

Correction, changed the direction that the rivets go in from.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Daniel Snell on Sunday, April 08, 2018 - 05:49 pm:

These are professionally done, thank you Martin for doing this, it is a great asset to the hobby...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Martin Vowell, Sylmar, CA on Sunday, April 08, 2018 - 07:35 pm:

Thank you, I try. :-)

Actually as I'm looking at this drawing now...I should leave the Driven gear and Woodruff Keys off and save it for the entire Transmission Drum pack assembly. Of course I could leave them on as "Reference Only" I suppose...hmmm, something to think about.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Martin Vowell, Sylmar, CA on Sunday, April 08, 2018 - 10:35 pm:

Went back and revisited the early brake drum drawing and found that the rivets heads were surfaced cut from both front and back...also notice that the drawing that I had previously thought was the 1914 cross section, was in fact the 1921-1925 assembly cross section. Although the part number T750 remained the same, even though the drums were completely different in configuration.

This is the correct 1909-1920 Transmission Brake Drum Assembly Cross Section.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Martin Vowell, Sylmar, CA on Monday, April 09, 2018 - 03:41 pm:

Revision....set the rivets back to their original position per Ford Drawings.

Went back and consulted the factory engineering drawings as to placement of the rivets...they go through the drum into the shaft flange and are peened there. Then you machine both sides to remove the excess of the rivet.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Martin Vowell, Sylmar, CA on Monday, April 09, 2018 - 03:44 pm:

Oh the Driven Gear is only for reference. It is not installed at this time.


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