Found a brake drum solution

[Merle Coggins]

It seems that I recall someone using a trailer brake drum, with slight modifications, a couple of years ago. You may have to do some searching through the forum to find it, but it sounded intriguing. 

[Racerstev]

I bit the bullet and bought the Mopar Pro drum. It fit’s and is one piece. 

 

Hated  to do it but was tired of dealing with it. 
 

Steve
 

 

[Ivan_B]

That's understandable. However, if we spent some time and find an alternative "relatively working" solution, now, that will be much appreciated by many folks in the future.

Do you still have your old drum to take some measurements of?

[Racerstev]

I have 2, one we tried to braze, warped badly, and a very rusty one. 
 

what measurements can I help with? 

[Ivan_B]

3 hours ago, Racerstev said:

I have 2, one we tried to braze, warped badly, and a very rusty one. 
 

what measurements can I help with? 

I assume that these are from your P8? These should be identical to my P10

Moreover, the front and back should be also the same except for the hub part, correct?

 

Let's go with the rusty one. Here is a diagram of everything we need (I think). The drum profile is shown with the hub removed (because we are looking to replace just the drum part. And here is the description:

 

1. hub center hole size

2. bolt hole size (drum part, not the hub)

3. thickness of the drum/hub mating surface (drum part, without the hub)

4. distance between the back of the drum/hub mating surface and the inner edge of the working surface of the drum (

5. distance between the inner working surface of the drum and the outer ring at the edge

6. distance between the edge of the drum and the outer ring

7. width of the working surface (I believe it is ~2")

8. thickness of the drum at the edge

 

Does the above make sense? I think that these should allow us to determine what modern drum will fit the stock hub with the least amount of modifications.

 

10 hours ago, Merle Coggins said:

It seems that I recall someone using a trailer brake drum, with slight modifications, a couple of years ago.

Thank you, I did a forum search and found the only one note about this from 41/53dodges He wrote about using a sleeve for the hub, (to fit the center hole, I assume) so I am not sure how simple it was to do 🤔

[Racerstev]

I got the drum off the hub yesterday, I’ll give some measurement's tonight I hope.  

 

A couple of notes, the center bore of the drum and the hub od are not even close to the same. So the drum isn’t hub centric. Guess it centers off the rivets. For our purpose’s We should shoot for hub centric?? 
 

The hub also has 2 steps on it. One very short one large. 

 

The rivets drill out very easily, very soft.

 

More later

 

Steve

[Racerstev]

1: 3.183”

flange 3.060”

2: .329” i didn’t drill the rivet out if the hub yet, this is what is sticking up out if the hub.

3: Did no measure yet

4: .971” from the edge of the friction surface to the face of the drum

5:not measured

6: .155” from edge of drum to the friction surface, or “the ridge”.

7: 2.265”

8:not measured 

 

Steve

[Ivan_B]

Hi Steve,

 

Thank you very much for your assistance. I expect that we'll need to get the new drum hub-centric, otherwise, we'll need to have it lug/rivet-centric, which could be more complicated. And I was certainly not planning to re-do the rivets

As for the hub, we just need to get its offset (the distance between the surface contact of the hub and the drum and the start of the pad working surface, if that make sense, to make sure that the new drum fits the way it should).

 

I am out of town, this week, so I'm not sure if I'll have time to look into the available drums and compare the sizes for testing. But I suspect to be able to order something next week.

[Racerstev]

54 minutes ago, Ivan_B said:

Hi Steve,

 

Thank you very much for your assistance. I expect that we'll need to get the new drum hub-centric, otherwise, we'll need to have it lug/rivet-centric, which could be more complicated. And I was certainly not planning to re-do the rivets

As for the hub, we just need to get its offset (the distance between the surface contact of the hub and the drum and the start of the pad working surface, if that make sense, to make sure that the new drum fits the way it should).

 

I am out of town, this week, so I'm not sure if I'll have time to look into the available drums and compare the sizes for testing. But I suspect to be able to order something next week.

That would be .971” from the outside face of the drum, or the surface the wheel contacts. Once I measure the thickness of the drum just subtract it,  

[9 foot box]

   I thought I should mention that the front and rear drums have different numbers. The 100 front and 106 rear numbers are for the drum w/o hub, according to my parts book. The other drums that fit, are for Nash and Kaiser. I have a front drum from a 48 Plymouth and a rear axle from a 53 Suburban. I’ll have to compare the drums on a flat surface. Ply33 is a good resource.

   Side view of front and rear drums for a P15. The center hole and bolt holes are larger than the hub, it needs the five rivets to keep it centric. 

Edited September 11 by 9 foot box
More information

[Ivan_B]

Okay, I am back at it. The front and rear drums do, indeed, have a different offset. So, we can either try to find two types of drums, or get one that is deep-enough for the front and cut it more shallow for the rear. I suppose that the later scenario is more realistic. I'll play some more with my own car, in attempt to measure the offset of both drums, and try to look-up if there is anything that will fit. We definitely want to have the drum hub-centric, if possible.

[Sniper]

If you are worried about hubcentric fit I would look at drum brakes from later model Mopars. Cuz I know the rims fit the hubs fine so one would assume the brake drum would too. Such as an 87 Diplomat they have 10 inch and 11 inch drum brake options for the Rears hope this helps