A question that might be unanswerable...

[moparedtn]

On our late 60's-early 70's drum brake cars, are the drum hubs different on 10" vs. 11" brakes?
Since the parts catalog only reflects the hub+drum assemblies themselves, that's no help....

 

[khryslerkid]

I wouldn't think they are different. Backing plates, shoes and hardware are.

 

[pnora]

I just looked in my 67 parts catalog. My guess is yes. I base that on the wheel bearings inner and outer are the same between 10 and 11 inch brakes.

 

[pnora]

I wouldn't think they are. Backing plates, shoes and hardware are.

He was asking about the hub itself.

 

[moparedtn]

I just looked in my 67 parts catalog. My guess is yes. I base that on the wheel bearings inner and outer are the same between 10 and 11 inch brakes.

Yes, bearings are the same.
The wheel center register and lugs and such are also comparable betwixt the two.
I suppose the exact question would be if there is any difference(s) in the face of the hub, where the drum
flushes up against?

 

[moparedtn]

I wouldn't think they are different. Backing plates, shoes and hardware are.

Of course - but that doesn't have anything necessarily to do with hubs.

 

[khryslerkid]

You would think the drum centers are the same.

 

[khryslerkid]

Craig at @mobileparts would know.

 

[moparedtn]

Maybe an even better question is whether the 3" wide shoes on the 11" vs. the 2 1/2" on the 10"
required a different depth dimension on the hub to get the respective drums located properly?

 

[khryslerkid]

Maybe an even better question is whether the 3" wide shoes on the 11" vs. the 2 1/2" on the 10"
required a different depth dimension on the hub to get the respective drums located properly?

They do that with the backing plate offset/backspace.

 

[pnora]

Maybe an even better question is whether the 3" wide shoes on the 11" vs. the 2 1/2" on the 10"
required a different depth dimension on the hub to get the respective drums located properly?

My thought is that it is in the backing plates. As far as I know the rear axles are the same 3 inch vs 2 1/2 inch. So I would think the same is true up front.

 

[moparedtn]

My thought is that it is in the backing plates. As far as I know the rear axles are the same 3 inch vs 2 1/2 inch. So I would think the same is true up front.

That makes sense, thanks. I also always assumed if I ran across 3" wide shoes that are listed for rear that they'd
be the same as for the fronts, too.

 

[moparedtn]

They do that with the backing plate offset/backspace.

Ok, so if the difference in width of shoe is handled at the backing plate + same bearings either way +
hub-centric & lug situation are the same....then the hubs would have to be the same as well, eh?

 

[pnora]

Ok, so if the difference in width of shoe is handled at the backing plate + same bearings either way +
hub-centric & lug situation are the same....then the hubs would have to be the same as well, eh?

I would sure think so. I only referenced 1967 on the bearings. There could be changes in other years but a guy would have to look it up.

 

[R413]

Maybe an even better question is whether the 3" wide shoes on the 11" vs. the 2 1/2" on the 10"
required a different depth dimension on the hub to get the respective drums located properly?

No, the difference is the depth of backing plates. The wheel mounting surface is in the same place. The track measurement is the same no matter what brakes.

Think of the rear axle, the axle shafts are the same no mater what size brakes are on it.

And to answer the first question, the front hubs are the same for 10" and 11" drum brakes,

 

[66 Sat]

There is another thread at the bottom of this one in the Similar Threads called "Differences between drum brake hubs?" that may offer some help. It has a photo of the 2 hubs side by side.

 

[moparedtn]

There is another thread at the bottom of this one in the Similar Threads called "Differences between drum brake hubs?" that may offer some help. It has a photo of the 2 hubs side by side.

Darn, wish the "search" feature on this site worked a little better.... thanks!
According to a couple posts on that thread:
a. According to the Dr Diff hub, not only do the different size drums share critical dimensions in hubs
but apparently so do discs of that era! (there's a change to bigger bearings in 1973 it indicates)
b. According to a another pic post on that thread, the only real difference between the 10" and 11" drum hubs
appears to be in casting thickness:

(10" drum hub on left - photo credit to @OKDart !)
Other than that, it appears all the drum-specific dimensions are the same....
which would also explain why the disc conversion kits/brackets out there utilizing existing drum spindles/hubs
are pretty much all the same, too.

More importantly, at least to me in this case - this eliminates a possible cause of an ongoing issue
I'm having with the brakes on Fred.
Finding the problem involves eliminating possible causes, after all.

Thanks to all who helped!