How deep is a score in a drum be befor it is not usable my score is 1/16 deep center of low drum?
My other question can you swap pre 25 drum with the wider late drum i know it takes the matching hogs head?
How much more brake doese this late drum give you over the narrow drum
I was considering swapping my brake drum to j&m drum siut either of my cars neither one in newer then 23
Also was there a support that bolted to the rear of the late block
Wrer the hogs head bolts running to the motor mount bolt on the frame rails
1/16 th inch is a bunch. Really depends on how much is left. Less than 1/8 th inch I'd scrap it. You can swap out a 26-27 brake drum with an earlier low and reverse. Makes a huge difference in braking. Don't need Rockies. If you use a 26-27 brake drum you need the 26-27 driving plate too. The 26-27 trans cover had both bolts to the block and straps to the frame. Needed for support when using the flimsy pan which used the four trough inspection plate.
Yes good size score since i have everything for the bigger brake
Might as well use it one cant have enouf brake in todays traffic
Found a good low drum now getting it apart for the swap
I think the large trans brake drum will make the brake band last longer than the earlier narrow drum brake and possibly brake a little better?
The problem might be if you have a three dip pan, the clearance may not be big enough for the wide brake band to fit while the drum may fit?
There are other reasons to put a 26/27 drum in place like the lug shoes that makes it possible to use the bulletproof Ford clutch pack without fearing for wear in the lugs.
Just to add to Roger's post about the benefits of the later brake drum, another advantage is the captured driving plate, making the assembly much more solid and eliminating the need for the second brake drum bushing.
Bob, in order to use a wide brake drum you will have to use a 4 dip pan, 26/27 hogshead, 26/27 driven plate, and wide band.
Thanks but i thinking i leave the small drum brake and run outside rear brakes since i using an aux tranny i had forgotton if you ever find neutral you get a surprise
My friend Lee Pierce (RIP) used a 26/7 drum cut down to the width of the earlier drums to get the advantage of the six replaceable tabs that mate with the clutch disks. I put the last ones in during one of our sessions on his 1912 touring.
Yes, Tony, I've done that myself. I did it from necessity because I didn't have an earlier drive plate that didn't have wear. I'll do it again if I ever do another transmission. Its simply a better design.
Ford made some narrow brake drums with the removable shoes late in the '25 model year.
Tony, there is another advantage to a narrowed down wide drum. The surface is continuous, not like the two part surface between the driven plate and the brake drum on the earlier type. Any mis-match between these two components hastens band wear.
Allan from down under.
benefits of the later brake drum, another advantage is the captured driving plate, making the assembly much more solid and eliminating the need for the second brake drum bushing. "END QUOTE"
The benefits of a captured driving plate does not exist, and is a bogus argument. More old wives tails, passed around with out thinking.
The 26-27 brake drum, driving plate is't any stronger then the earlier style.
When they made the drum hang out over the driving plate, they had to eliminate the out side lip, no need, or place for it.
It is the six bolts on either driving plate, and either brake drum that provides the strength for that union.
The only weakness in the break drum and driving plate is the rivets, more so on the driving plate.
Now then the reason for not using just, but one brake drum bushing is
1. If you leave out the inside bushing, 100 times more oil will get inside the brake drum shaft, rather then go into a small hole between the two.
2. The biggest reason is you don't need 3 bushings for the center shaft to run. Two bushings is all you need, as any time you add a 3rd bushing, then alignment is way more critical.
I watched a rebuild video some one had made, and the run out was stated at .004 to .006 thousandths.
If the tail shaft, and the brake drum would have been cut as a unit, instead of separately, there should never be any run out. I never have any!
Machining the face on the brake drum, and the face where the driving plate bolts, is a waste of time, it helps nothing.
The alignment has to be in two places.
1. The end of the shaft on the brake drum assembly, and the end of the tail shaft ball cap area, which should always be trued. You have to center in side of the tail shaft to get rid of any forth coming run out.
2. The one bushing in the brake drum, and the one bushing in the driving plate, have to be align reamed, or you would have to bore over size for clearance for the main shaft not to bind.
I seen some pictures where years ago, some one butchered a crankshaft flange, the center of a flywheel, and the flange on a main shaft for adjustment, centering. What a waste of time.
To have perfect center in the crank, transmission, and the brake drum and tail shaft.
1. You have to grind the crank on it's true center line.
2. The main shaft has to be straight, and the flange.
3. Brake drum, and tail shaft trued as a unit.
4. Inside bushings align reamed, and you can't do that on a lathe, with each piece separate.
One last thing about the drum surface where the band rides. These surfaces are no different then then the brake rotors on the front of your car, when you install new breaks, you true the drums, or install new rotors.
Model T drums are no different, when the surface wears, they don't wear even. They have dips, and valleys, and always lean to the outside edge.
Wore drums will chatter, and float just like warped rotors on your modern car. Plus, you will not have 100% surface contact, of band and drum surface.