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Well this may be a stupid brake question: where to measure to determine if I have 10 or 11s?

OneWheelPeel

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First the questions and then the long story :p
This is a 69 Coronet 440 with barely any options. Non power drums all around.
1) Where do I measure to determine if I have 10 or 11s? If I measure the outer edges of the drum I'll easily be at 11. Do I measure there or across the inner drum surface?
2) Also I don't see a spring and hardware kit available at my local parts chains, where do you guys go for a good kit?


Now the whole story:
For awhile I've noticed when first setting off the rears, or maybe one rear, not always easy to tell, would lock with very light brake pressure. When that happens after a couple of stops I can't reproduce the issue, even on a dirt road. I thought maybe it was the combination of contamination and temperature of the shoes, so I pulled the drums to look today.
Driver's side seems worn but ok:
20241127_122017.jpg

20241127_123125.jpg

Pass side is another story, definitely was contaminated but not wet and I didn't see an active leak. Possibly the cylinder was changed a long time ago but the rest wasn't cleaned? Also the bottom most spring was broken which I think it the real issue. Is it possible that bottom spring situation is related to the adjuster when backing up and then it takes a few stops to get back in place? I figure its that or the contamination. Pics of the pass side mess:
202411127_125110.jpg

The axle is blocking the full view of the broken spring so I highlighted what remains of the spring and where the other end likely went in the pic.
 
You can also measure across the shoes and that will also tell you the difference.....
 
First the questions and then the long story :p
This is a 69 Coronet 440 with barely any options. Non power drums all around.
1) Where do I measure to determine if I have 10 or 11s? If I measure the outer edges of the drum I'll easily be at 11. Do I measure there or across the inner drum surface?
2) Also I don't see a spring and hardware kit available at my local parts chains, where do you guys go for a good kit?


Now the whole story:
For awhile I've noticed when first setting off the rears, or maybe one rear, not always easy to tell, would lock with very light brake pressure. When that happens after a couple of stops I can't reproduce the issue, even on a dirt road. I thought maybe it was the combination of contamination and temperature of the shoes, so I pulled the drums to look today.
Driver's side seems worn but ok:
View attachment 1764543
View attachment 1764545
Pass side is another story, definitely was contaminated but not wet and I didn't see an active leak. Possibly the cylinder was changed a long time ago but the rest wasn't cleaned? Also the bottom most spring was broken which I think it the real issue. Is it possible that bottom spring situation is related to the adjuster when backing up and then it takes a few stops to get back in place? I figure its that or the contamination. Pics of the pass side mess:
View attachment 1764548
The axle is blocking the full view of the broken spring so I highlighted what remains of the spring and where the other end likely went in the pic.
I don't see a jack stand under there either. Don't be like Brad.

Brad.jpg
 
Usually, 11" brakes only came on cars with 26" radiator.
Mine came with some aftermarket aluminum rad. Figures one of my roughest cars ever has the fanciest radiator I've ever had.
Drum size refers to the inside measurement. If you have approximately 11" measurement on the outside, you've got 10" inch brakes.
That makes a lot of sense, I also compared the broken spring piece I have to some pics and it matches the 10 inch stuff. 11 inch hardware is different. I'll probably still double check because of paranoia.
 
My car with 11" brakes uses manual adjusters. My 10" brake car has self adjusters.
Your self adjusters are a pretty good clue that you have 10s too.
 
My car with 11" brakes uses manual adjusters. My 10" brake car has self adjusters.
Your self adjusters are a pretty good clue that you have 10s too.
Yeah I would say that pretty much answers that. While looking at the usual sites they show two different width shoes for the rear 10 inch brakes. Any clues from the pics there?
Dodge just can’t make things simple.
 
Well even if they would, it would take forever to wear out the new ones. Its not like I would get another mopar down the road that could use them, people don't do that.
Riiiiiiiight?
 
Usually, 11" brakes only came on cars with 26" radiator.
Didn't all RR's and Bee's come standard with 11" drums? The bulk of those cars had 22" radiators.
 
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