mechanical drums vs. hydraulics/wide 5's

cuzncletus

cuzncletus

Senior Member
On my 39 rear, one of the drum had the edge broken. My guess is someone tried to pry the drum off not knowing you needed the special wheel puller. It's usable and was running but I wanted to replace it for cosmetic reasons as it's on a 29 A/v8 roadster.

I got a "39" drum off of EBay that was good, only it obviously wasn't a 39. My guess is it's some year of wide 5 that was mechanical between 36 and 38. I cleaned it up, put new seals and bearings in it, and attempted to put it on. It refused to go. The keyway is the same width. Does anybody know the hangup on using these drums?
 
36 takes a different bearing and seal but fits. 37 38 were one piece. 39 the hub and drum are 2 seperate pieces but they will all fit on a banjo rear.
 
Not so fast guys..........JM35 explains it fairly well below! DD

"The large rear bearing was carried over from '35 into '36. Then (exact date unknown to me) a smaller OD rear bearing was introduced. This meant there were two rear hub/drum assemblies used thru Feb/Mar of '36. Then the larger bearing was discontinued and all future production used the small bearing only. Based on info from the 1935-36 Book by Don Rogers."
__________________
John
 
Bob C said:
Isn't the ID the same on both bearings?

Bob
Click to expand...

Bob.....This is one of those deals that I've heard the stories about for umpteen years, but I've never had the pleasure of trying to figure-out first-hand. I honestly don't have the difinitive answer, but it may give the OP a good place to start looking for the REAL answer.

Maybe DON ROGERS can step in here and learn us all something. DD
 
cuzncletus said:
On my 39 rear, one of the drum had the edge broken. My guess is someone tried to pry the drum off not knowing you needed the special wheel puller. It's usable and was running but I wanted to replace it for cosmetic reasons as it's on a 29 A/v8 roadster.

I got a "39" drum off of EBay that was good, only it obviously wasn't a 39. My guess is it's some year of wide 5 that was mechanical between 36 and 38. I cleaned it up, put new seals and bearings in it, and attempted to put it on. It refused to go. The keyway is the same width. Does anybody know the hangup on using these drums?
Click to expand...

How far does it go on before a stopping point is encountered? DD
 
With the shoes fully retracted, it makes it until about the first two threads of the axle are showing. As to the post that said all 36-39 drums are the same, I've looked at a bunch and they are definitely not, at least appearance wise. There's a difference in the inner seal OD plus differences in ribs on the outer ring, a spiral reinforcing design cast into the replacement I have like others I've looked at, and other changes from year to year.

When I go back to the garage tomorrow I'm going to look at interior ID on the earlier drum. When I put a 39 drum on, which fit very easily, I found the threads buggered on the 5/8" OD axle end about 11/2" in.. This sent me in search of a 5/8"-18 die which stopped my progress but got me to thinking. Did the threads get buggered when I tried to press on the earlier drum? My understanding was the axles were the same for many years. Was this another erroneous piece of information we've all relied on for years? Stand by for my results.
 
Did you try putting the drum on without the key? Sound like that could be your problem.

As far as the rear drums fitting
All the wide 5 rear drums will fit. Different cosmetic things like fins and sprial webs ect wont keep it from working. Just the early 36 took a different bearing and seal
 
When I used to be in adult education, we used to say; "There are no stupid questions, only stupid people asking them." So consider the source on this one:

When putting my rear brakes back together I put the shorter shoe forward. I thought I had them marked this way. Looking at Van Pelt's exploded drawings I obviously did it wrong. My question is the metal on all the shoes all looks the same, front and back, side to side. Looking at two sources including Van Pelt's there is only one part number listed for all the shoes so while I can see where the braking might be affected (marginally) by the rear shoes being reversed I don't understand why it would cause binding and difficulty in assembly. Sometime after 39 the shorter shoe concept was simply dropped.

In measuring the mechanical drum vs. the hydraulic drum, all critical dimensions are the same. 12" ID, same bearing ID, same drop from the rim of the hub to the upper contact surface just above the seal. Obviously I've done something wrong but I can't believe it could be as simple as reversing similar shoes. Anyone with any experience here?
 
Used drum? Did you have it turned before putting it together? If not maybe the brake surface is worn in a taper you cant see with your eye.
 
If your backing plates have eccentric lower shoe centering bolts they may need to be adjusted for the different drum.
 
OK. Got it. This may not be the definitive word on 36-39 Ford drums but it's my experience. #1. If you put the shoes on backwards (short shoe, if you have one, in front) the drum will not go on easily. Put it together properly and it falls together. Don't ask me why as it appears all metal parts are identical and the friction measured the same thickness. #2. The non-39 drum I have has the "pinwheel" cast into it. After all the shoes were correct it slipped right on. The only real difference in fit is that the pre-39 fit inside the outer rim of the backing plate vs. the 39 fitting over the backing plate. This put the castle nut slightly farther out but still easily secured with a cotter pin. There is a different inner seal required but they're easily attainable.
 
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