I picked up a 6-lug 9.5" rear w/11.2" drums the other day, 4x4 width. This will replace the 8.5" w/ 11.2" drums on my Suburban.
I'm looking at the brakes on the 9.5" rear... yeah, they're 11.2" diameter, but the drum is a
LOT (2x?) heavier than the 11.2" drums on an 8.5", in part due to the extra iron in the drum to accommodate the OFFSET from the axle's flange to the backing plate (see picture).
The JB6 brakes use a 2-3/4" wide shoe (I measured them).
Look at that flange offset on the 9.5". It could,
with a different drum, accommodate a 4" wide shoe.
Now I'm wondering: Was this same 9.5" rear used in another application, like a van, where it was given a much wider drum?
Otherwise: Why did GM stick that 9.5" axle flange so far from the backing plate, when they didn't do so on the 8.5"?
Observation: The
heavy 11.2" drum used on the 9.5" rear likely has much better performance as a brake vs. it's 8.5" counterpart, not in terms of braking force but it's much greater mass can sink much more heat, as might occur on a long downhill grade or a heavier load.
Below: 9.5" axle flange, 11.2" shoes and backing plate
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Below: 9.5" drum next to 8.5" drum, both 11.2" JB6
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Below: 8.5" axle flange, 11.2" shoes and backing plate
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Below: Treasureyard 9.5" 6-lug 4x4 rear w/ 11.2" drums
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