Help with back brakes please!

[GMJimmy]

Well believe it or not I rebuilt my entire rear end and didn't realize at the time what size the brake drums were. Anyway to fix a pulsation I machined the drums. Not paying too much attention to the width until I measured them and decided to replace them did I find they are 11 X 3 inch and shoes are 2-3/4. Looking up replacements I'm finding they come up as 11 X 2 inch? What trucks used 11 X 3 and if I change the shoes and drums could I use the 11 X 2 inch? The truck is a 68 short bed but I'm pretty sure it has a 72 rear axle in it.
Thanks.
Jim

[jradford]

Go to Rock auto and type 72 chevy the year of the axle. Look at the C20 and C30 brakes. Sounds like you have a 72 3/4 ton axle in it. Just did mine on my 72 C20 and the 11.16x2.75 shoes fit just fine. Good luck.

[GMJimmy]

Originally Posted by jradford

Go to Rock auto and type 72 chevy the year of the axle. Look at the C20 and C30 brakes. Sounds like you have a 72 3/4 ton axle in it. Just did mine on my 72 C20 and the 11.16x2.75 shoes fit just fine. Good luck.

Thanks for the feedback. Did a 3/4 ton use a 12 bolt rear end? I would think it would be bigger?? When I did the rear end, new posi unit and gears I ordered parts for a 1/2 ton and everything fit like a glove.
Thanks

[GMJimmy]

Just looked up 3/4 ton on Rock Auto and they are 8 bolt. Mine are 5 bolt?

[jradford]

1/2 tons could be ordered with the full floater rear ends like the 3/4 tons. If it had c-clips it definitely is a 1/2 ton axle. If it has c-clips and uses the larger brakes that came with the 3/4 ton trucks then perhaps the backing plate was changed to get larger brakes on the rear. I was doing a little research and the 1/2 and 3/4 ton carriers should be different. Might be best to just get a good measurement on the old drums or carry them to the parts store and just do a match up and figure out the details later. Does sound like an odd ball. Maybe the rear end is out of something besides a chevy or gmc. These axles were used in many different vehicles. I think all the way into the 80's. Wonder if it may be out of a later model HD truck. Should be numbers on the axle tube.

[GMJimmy]

Originally Posted by jradford

1/2 tons could be ordered with the full floater rear ends like the 3/4 tons. If it had c-clips it definitely is a 1/2 ton axle. If it has c-clips and uses the larger brakes that came with the 3/4 ton trucks then perhaps the backing plate was changed to get larger brakes on the rear. I was doing a little research and the 1/2 and 3/4 ton carriers should be different. Might be best to just get a good measurement on the old drums or carry them to the parts store and just do a match up and figure out the details later. Does sound like an odd ball. Maybe the rear end is out of something besides a chevy or gmc. These axles were used in many different vehicles. I think all the way into the 80's. Wonder if it may be out of a later model HD truck. Should be numbers on the axle tube.

Thanks for the help. After working on the front end of my truck (I'm pretty sure it has a 72 frame and front end as I found 68 parts don't fit. I found some applications that used 2-3/4" X 11-5/32" brakes. I measured the wheel track of my truck (i forget what the numbers were) and found the rear tracking width is wider than the front. Haven't researched what the stock measurements are so not sure if this axle came out of a C10 or not but the 74-86 C10 used 11-5/32" X 2-3/4" rear brakes. At least I know what to order for parts.


Chevrolet Truck Applications:
1978-82 Blazer RWD
1977 Blazer RWD Manufactured Before June
1976 Blazer RWD
1975-86 C10 with 2.75" Rear Shoe
1974 C10 Pickup with 2.75" Rear Shoe
1989 R1500 Suburban
1987-88 R10 Suburban
1976-86 C10 Suburban
1974-75 C10 Suburban with 2.75" Rear Shoe


GMC Truck Applications:
1980-86 C1500 with 2.75" Rear Shoe
1979 C1500 with 2.75" Rear Shoe
1975-78 C15 with 2.75" Rear Shoe
1974 C15 Pickup with 2.75" Rear Shoe
1974 C1500 Pickup with 2.75" Rear Shoe
1976-82 Jimmy RWD
1987-89 R1500 Suburban
1979-86 C1500 Suburban
1976-78 C15 Suburban
1974-75 C15 Suburban with 2.75" Rear Shoe
1974 C1500 Suburban with 2.75" Rear Shoe