Sorting transmission drums and plates

[Steve Jelf]

The transmission repair I cobbled together worked OK, but while everything is apart for some engine work I should put in a better brake drum. So I've been going through drums and drive plates to see if I have any that are good enough to use. Matching up a drum and a drive plate is complicated by changes over the years.

The DB mark tells me this is the earliest drive plate I have. If I remember correctly it came out of a transmission with a 1913 date stamped on the main shaft. I believe this is a later version of the brake drum that fits it, but they fit together correctly.

Putting them together you see that the plate forms a continuation of the drum surface.

Here's one of the 1925 drums. It has disk lugs separate from the bolt holes, and the lugs have steel shoes to prevent wear by the disks.

This drive plate fits into the flange on the drum, and the bolt holes line up perfectly, but the drive plate edge is recessed from the drum surface.

Here's another drum with separate lugs and steel shoes. The early drive plate shown in the first two pictures fits it perfectly, BUT the bolt holes don't line up. I assume there are drive plates that fit and have holes which do line up, but I don't have one.

I like the steel shoe idea, but I don't like the mismatch of edges with one combination and the hole problem with the other. I suppose the best plan would be to pick out the earlier style drum with the least disk wear on the lugs and file them straight.

[Dan McEachern]

The driven plate that has the OD smaller than the brake drum is a 26-27 Driven plate. It is smaller because they register inside the wider brake drum rather than on the step on the face of the brake drum like the earlier design. You can use an earlier driven plate with your brake drum with the lugs by machining (preferred) or filing the bolt holes in the driven plate. The holes are on a slightly smaller bolt circle on the 26-27 brake drums and driven plates.

[Allan]

Steve, it is most important that the drum surface and the outer diameter of the driven plate are as near to the same as you can get, as together, they form the surface on which the bands engage. If you can manage this using a brake drum with the steel lugs, you have the best combination, but I would not compromise this match just to get the steel lugs on the drive plate.

Allan from down under.

[D.Yoder]

My 24 touring has the 25 lugged break shoe with a older tail shaft that the holes were maschiened to fit.
More than 100,000 miles ago. Not the best way to go . But can work.

[Wayne Sheldon]

I am not sure, but I have read, and I believe there may have been an in-between driven plate that had the larger outer diameter to match those late '24 through late '25 narrow band (but with the replaceable lugs!) drum. As already mentioned, the slightly smaller driven plate is for the '26/'27 wide band drum, and meant to fit inside the drum's outer surface. If (and I will say "if" here as I am not certain such a thing ever existed?) there are such in-between driven plates? They must be fairly rare, as I have heard of quite a few people having problems finding a driven plate that fits with those drums.
I personally have some misgivings with the idea, but Dan McE's suggestion to elongate the holes to fit an earlier driven plate may be the best. Dan is usually right about such things. Being careful to not enlarge the holes ANY extra, and it should work fine for a very long time.

[RajoRacer]

There is a segment in the original Ford Service Bulletins regarding the bolt spacing on the driven plates and how to modify one to fit.

[JWalters]

My 24 touring has the 25 lugged break shoe with a older tail shaft that the holes were maschiened to fit.
More than 100,000 miles ago. Not the best way to go . But can work.

Can't argue with 100,000 miles of tested and trued results.






Jason Walters