Drum differences

[SUX2BU99]

The diff that was on my truck seems to have had smaller drums than the diff that I bought from the boneyard. I found this out after trying to fit the smaller drums onto my new brake shoes and saw that they would not fit. Even after tucking the brake adjuster wheel all the way in. And I had just spent $25 getting them turned!  So I had to put the other drums on for the time being. I still have the brakes backed off all the way but I have to get them turned now. And one of the weights on them fell off but driving on the highway, no vibration whatsoever so that's good at least. Ugh, I hate these kinds of surprises.

So, what's the deal with the two different drum sizes?? Both diffs are truck 12 bolts with 5 lug axles.

[VileZambonie]

There were 11x2 or 11x2.75

The heavy duty brakes were 13" drums

[SUX2BU99]

Well that's weird, I wonder why the difference then? On the side of the drums, the 'big' ones say max. dia. is 11.20" but the 'small' ones say 11.09". Do I perhaps have drums from a different 5 on 5 vehicle?

[Dragon]

Well that's weird, I wonder why the difference then? On the side of the drums, the 'big' ones say max. dia. is 11.20" but the 'small' ones say 11.09". Do I perhaps have drums from a different 5 on 5 vehicle?

Yeah almost sounds like someone Cheaped Out, and used an Assembly off of like a Chevy Caprice/Etc from Wrecking Yard Pieces(Wouldn't suprise me, as some idiots/cheapskates have done that around here)......

[VileZambonie]

That's drum diameter. I listed you the 2 different shoes.

[SUX2BU99]

Yep, I know that. I'm just not understanding why the shoes would not fit within the drums that have a smaller max. outer dia. than the ones that have a larger max. dia. I recall the parts store guy asking if I had the smaller or bigger shoes but he was asking about the shoe width, which as you had indicated came in 2 sizes. I'll have to check around to see if the Caprices and such came with slightly smaller drums.

[SUX2BU99]

I think i found my issue. I checked at Autozone.com and they list 2 different dia.'s of shoes for my year of truck: 11" and 11 5/32", in two different brands. That makes sense as to the just slightly larger fitment of my new shoes to my old drums.

Hm, when I change the year to 1979 for my truck, it lists 11" and then 11 11/32".

When comparing the looks of the 2 drums, the larger ones have wider fins on them than do the smaller drums. If you buying new shoes for your drums, make sure to measure them carefully!