MTFCA Forum

I decided that there just wasn't enough changes to warrant making a 1918-1922 and a 1923-1927 versions of this drawing, so I opted to stipulate the only thing that seems to separate them by the year that the pinion changed from the 2 pinion differential to the later 4 pinion differential. And since the differences between those two as so slight (hardly noticeable, a very slight modification on the gear housing), I thought that since the Axle housing doesn't change I'd just make one inclusive drawing to cover them both.
If I'm in error, please let me know when and where these changes (if any) occur and I will add them to this drawing (if they're not more than a small change to a part or two) or make a new drawing for the other year span if they're a bit more complex...but I don't honestly think there are any other than maybe that 8 sided keyed washer on the tail end of the worm being round rather than the 8 sided one, because I've seen one like that. If that's a later model part, let me know and I'll add it to this drawing with a reference to the year it was used. Also I know that some folks have put shims between the thrust bearing and the Hyatt bearing sleeve, but since I could find no part number for that shim (or thickness), I've left it off. If any of you guys knows what that number may be, please let me know so I can add it also.

Normally I wouldn't include the spring perch on the rear axle assembly, but it seemed necessary to have something that bolted that bloody backing plate to the axle housing, otherwise it would just be sitting out there with nothing to hold it to the housing. It seemed the best choice, since the radius rods go with the Drive Shaft Assembly and the brake pivot and brake expander go with the Brake Assembly.

There are two other changes I'm aware of:

1. Your drawing appears to include the "bead" on the clam shell (Part 1002) at the axle tube opening. This was the early version. Later units did not have the bead. I don't know the date of this change, but it roughly coincides with the pinion change.

2. Your drawing includes the plug and threaded hole in the cap (Parts 1004 and 1012). These were included on later TT rear ends. The earlier ones did not have the plug and threaded hole, just a plain cap. This too was changed sometime around when the pinion change was made.

Sorry I don't have precise dates for these changes. Maybe someone else can help with them.

You seem very interested in authenticity and accuracy, and it's in that spirit I offer the following:

It took me a while, but I thought something was missing. Your drawing shows 4 felts, 2 on each side, 1 inboard of the Hyatt bearing and one outboard of the Hyatt bearing. You've also shown the modern replacement for the inboard felt. These felts are intended to retain Hyatt bearing grease within the bearing/sleeve. So far so good.

What missing is another pair of felts. Further inboard, just outboard of the inner ball bearing, there is an axle shaft retainer cup (Part 1025), an axle shaft retainer plate (Part 1026) and a felt. This assembly is present on both sides. The two of them prevent rear end oil from escaping the rear end housing .

I hope this helps.

Henry, my drawings are as Ford built them, not as we today would build them, so, yes I try to put everything in the assembly as they "originally" were. Any modern equivalent is usually added as a boxed alternative with it's modern part number and or description.
So you're saying that it has one of the riveted in cups for a felt seal on both sides of a housing half? Hmmm, that's something I didn't know, although I did wonder about the rivets on the large housing and why they were placed so close to the bearing...they hold another cup then right? Ok I'll make that change. Is that inner cup and seal present on all years? Do you substitute one of the modern seals there like on the out side as well?

Changing the "bead" on the housing is sort of a major change (meaning it is too big to show a different housing configuration)...I may just have to draw another drawing for the later years after all. Ok, fun never quits.

Is this correct?

For 18-22 And 23-27

The corrections as to the cap/threaded hole/plug look great, as does the correction for the "bead".

That inner felt matter is a little more complicated. It looks like what you've labeled 1025 is actually the retainer plate part 1026. What you've labeled 1026 looks like the felt which is actually 1021, and the retainer cup, part 1025, is not shown.

Also, note that the felt is inserted into the retainer cup, then the retainer cap slips in to contain the felt. The entire assembly just slips into place. There are no rivets. Unfortunately, for the life of me I cant remember if the retainer plate faces inboard or outboard. I'll look around and see if I can figure it out. Maybe you can see it better in this drawing (the lower one):

Unless cup 1025 comes out and is not riveted inside the housing, there is no way to show it, unless I break away that section of the housing for both the inboard and outboard seals. However, if nothing holds that cup within the housing and or it sets against a flange or something and is removeable, then I can place it outside of the housing, but if it is riveted in, then as far as I'm concerned it is part of the housing.

1918-1922 1923-1927

Actually, if you show 1026, 1021, & 1025 just like you've shown 1023, 1021 & 1022 you'd have it pretty well nailed. 1021 and 1026 are fine the way you have them. Just slide them a little to the left and add the same graphic as you used for 1022.

Yes, cup 1025 just comes out, no rivets.

Oh good, how about this?

1918-1922 1923-1927

Looks good to me!! Nice work.

I think the worm roller bearings have an odd number of rollers. Also, something real important to the TT rear axle is the front worm seal. This seal is part of the driveshaft/torque tube assembly, but if there are no plans to draw that then maybe the back of the driveshaft could be shown here? The issue with the felt seal in front of the worm is that occasionally it gets removed or destroyed during restoration and then is overlooked because it isn’t a source of a visible leak. If that seal isn’t present, the action of the worm gear at continuous road speed has a tendency to pump the differential lubricant up into the torqe tube and the runs the differential housing dry.

Martynn,

I just noticed another part not shown in your drawings. The Axle Housing Drain Plug (Part 1012) and corresponding threaded hole in the right side (passengers side) axle housing. You'll see it in the lower drawing I posted on this tread earlier. It's to the lower right side of the drawing on the lower part of the clam shell.

Actually, the differential drain plug and filler plug aren’t shown.

Adam,
Look at the last pair of drawings. The upper drawing is for 1918-22, at which time there was no upper plug. The second drawing is for 1923-27 and does show the upper plug. Missing in both drawings is the lower plug.

Really good work Martynn !!!

Henry, I just noticed the same thing, that I forgot to put in the drain plug

Adam, the Thrust bearing had 11 balls in it, and the but the Hyatt's (both short and long) have 8...I count everything to make sure I get it right. Like there are 13 housing bolts, yet since one of the bolts appears behind the axle, it's not shown, I can't show them all unless I blow them really far out from the axle housing half and really there is just no reason to do that just to show one bloody bolt.

Made the change.

1918-1922
1923-1927

Looks good Martynn.
Nice way the backing plate is shown attached and exploded.