I need to know how to measure brake drums on my 55 Thunderbird

[JDJ]

could anyone help me measure my drums to know if they are still “thick” enough to use. I believe they are supposed to be 11.06 inches across (measured inside) . They have a number 1106 stamped on the drum. Does that indicate 11.06? I had them very slightly turned just to make sure they were round and they measured just a tic over that. They are “FoMoCo” drums. They also have a machined slit in them from the outside in??
It looks like theslit was machined into the drum maybe to indicate when they would show that they were machined to there widest tolerance?? I’d send a photo if someone could explain to me how to add photos to a post.

Thanks, JDJ

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[fordrodsteven]

JDJ, to add a photo to a post you click on the tab that says "upload a file". The site will open another window whwere you can find the picture you want to add. Once you have located the picture you click on the "open" button and it will add the photo to your post. then you click on "post reply". I think there is a size limitation so you might have to edit "resize" your pictures to make them small enough files for upload.

 

[JDJ]

JDJ, to add a photo to a post you click on the tab that says "upload a file". The site will open another window whwere you can find the picture you want to add. Once you have located the picture you click on the "open" button and it will add the photo to your post. then you click on "post reply". I think there is a size limitation so you might have to edit "resize" your pictures to make them small enough files for upload.
View attachment 4306

Thanks Steve

 

[JDJ]

Regarding measuring my drums. Here are photos of the 55 thunderbird drums

 

[CSPIDY]

That doesn’t look good, never seen anything like that before.
Do all 4 drums have this slit cut into them?

 

[Dale Leonard]

That hole looks like the brake shoe was rubbing the back of the drum. I would definitely replace the drum or drums if needed. I do not like the worn hole and you need to figure out why this did this.

 

[CSPIDY]

That hole looks like the brake shoe was rubbing the back of the drum. I would definitely replace the drum or drums if needed. I do not like the worn hole and you need to figure out why this did this.

What would cause the slice in the outer face of the drum? Looks like someone took a cutoff wheel and cut it.
I do agree, he needs to replace the drums.

 

[Tater Salad]

Regarding measuring my drums. Here are photos of the 55 thunderbird drums

I have the same machined slot in mine and made the assumption, it is an indicator for how thin they can be turned. The slit is not done by anything internal it was made at the factory.
As for your question on what's to thin or over turned. I assumed once the slot was opened all the way, they were finished

 

[fordrodsteven]

Looking at those slits from the outside of the drum they are too straight to be cut in by accident or wear. They appear to have been machined in. I don't know the purpose and I would have to do some research. I might possibly pull a tire or two off of my rolling frame to see if the slits are in my drums.

 

[Dale Leonard]

My bad
After relooking at the slots I now see that they are machined into the drum from the outside and very well could be wear indicator slots. Will now have to do some research.

 

[JDJ]

I have the same machined slot in mine and made the assumption, it is an indicator for how thin they can be turned. The slit is not done by anything internal it was made at the factory.
As for your question on what's to thin or over turned. I assumed once the slot was opened all the way, they were finished

Tater and all other responders,
Yes all four wheels have the same “slit” or as I think “wear indicators” in them. I was told that a couple of months ago but wanted more opinions.
I thought that same thing that they were done at the factory. They must have had a j

My bad
After relooking at the slots I now see that they are machined into the drum from the outside and very well could be wear indicator slots. Will now have to do some research.

Please let me know what you find out.

 

[Dale Leonard]

Brake drums are slotted so that the brake lining to drum clearance can be checked.
If oversize linings are used, the drum must be rebored in an amount equal to the increased thickness of the linings. Otherwise it is impossible to obtain the specified lining to drum clearance.
NOTE: Do not remove more than 0.030 inch of material when reborn brake drums (0.060 inch on the diameter).

When adjusting the brakes you insert a 0.010 feeler gauge into the slot while the slot is opposite the lower end of the primary brake shoe.Make adjustment to obtain this clearance. Rotate the brake drum to the upper end of the primary shoe and check the clearance to see if it is 0.010 and if greater than 0.013 then you loosen the anchor pin nut one full turn. Then you have to rotate the eccentric to obtain the correct clearance.
This is found in the 1955 Ford Car Shop Manual.

Hope this helps

 

[Dale Leonard]

1955 Tbird brake drum I.D. = 11.000 and max bore is 11.060 for front and rear.
Lining width for front is Pri = 1 3/4" and Sec. = 2 1/4"
Front wheel cyl. dia. is 1 1/8"
Rear lining width is 1 3/4"
Rear wheel cyl. dia. is7/8"
Master cylinder dia. is 1.000"