I know there are 2 different drums, one with 2 holes and one with 6 holes. I read somewhere they are not interchangeable, but I don't know if that is correct or not; I haven't seen a difference other than the holes.
Can anybody shed some light on this?
I was thinking the drums with more holes is for the earlier cars. OR it may be the other way around!
The earlier drum has to be used with more of the washers to get the correct clearance between the drum and the brake drum when putting the drum assembly together. I also think I read that here on the forum.
Maybe some else could make it a little clearer that is a little more knowledgeable.
I thought the geometry of the disc drums was the same (except for the holes) and the difference was in the brake drums.
If memory serves, I once measured the two types and they were the same in the critical areas. I hope I am not wrong on this.
The early drum was used with the brake drum bushing made right on the main shaft bushing.
It's total thickness in thinner then the three washer type.
The old drum will work with the three washers if you lath off .015 thousandths from the area that goes next to the washers, and set the clearance to .015 thousandths end play, and no less.
So if I understand this correctly the issue boils down to the clearance / washer / bushing issue..... I am familiar with that and have the clearance adjusted properly..... At least it will be when my last washer arrives, I pre-tested it with shim-stock between the 2 washers I have.
I believe the early flanged brake drum bushing was used through 1916, and requires a distance plate, which is a thick large clutch disc. I'll go along with Richard on the clutch drum.