Heavy Duty rear drum brakes for 1/2 tons... FYI

[Tx Firefighter]

I learned a little nugget a few weeks ago. Some 1/2 tons had much larger rear brakes than most. This isn't like discovering Plutonium or anything, but it's not common knowledge.

I swapped rear ends under my beater, and took pictures of the differences. Both were 5 lug 12 bolt normal rearends.

I don't know what option code to look for, but I was told this is a 72 Suburban rearend.

It would be a good way to get better rear brakes.

The overall width is identical, so it doesn't affect track width or wheel and tire fitment. The extra depth is in the backing plates. They are dished on the wider setup.

[lolife99]

Thanks for the HOT tip. You learn something every day. Maybe this is the heavy duty brakes that ECE sells.

[junkyardjohn]

I Took The Complete Rear Brake & Drum Assy. Including The Backing Plates Off Of A 75 C-10 , That I Was Pulling The Front Crossmember Assy. Out Of To Put Under A 69. The Shoes Were About 2 5/8" Wide Instead Of 2".I Put Them On My 69 & It Made A Noticable Difference. John

[72swbcamo]

I bought the heavy duty brake upgrade from ECE. I thought it was a little pricey but you get everything brand new. It would be a lot more work to find a rear with the bigger brakes and have to disassemble them, clean and replace all the worn parts. So it may be woth it. Those larger finned drums don't come cheap. I'm glad to hear that there was a noticeable difference in the braking performance. I guess the it will all be worth it.

[72BlckButy]

Originally Posted by lolife99

Thanks for the HOT tip. You learn something every day. Maybe this is the heavy duty brakes that ECE sells.

That's the same thing I thought after reading his post...

[mbgmike]

The 11" x2" were used from 1963 to 1975.The larger 2.3/4" x11.5/32" were also used in the early 60's up to 1975. Just about any engine combination from 230 up to 454 and any 1/2 ton truck,burb or van.The same parts on certain years are also found some Dodge trucks and also some Jeeps. I don't have a clue why their are some many combos.

[mbgmike]

Some 1972 trucks did not have them and some did. seems like more 70 to 71 models had them than others. Its really confusing to see all the combinations. Thats why its so hard for parts guys to get the correct ones. I think all the 305 V6 GMC trucks had them but not entirely sure.

ECE just sell the larger brakes is correct like most all parts companies. Nothing special

[matthufham]

interesting, makes me want to find out what i have in my 72.

problem is, i can't get my drums off! they seem to be stuck on. i checked the parking brake, blew some dirt out of the inspection holes, hit them from all directions with a ball peen hammer, still don't want to come off. is there a trick here? maybe someone could just measure the drums so i don't have to measure my pads.

[Tx Firefighter]

Hit the drums real hard perpendicular with their face. Hit them on the smooth part right behind where the wheel mounts. I used to get some real stuck drums on the mail trucks. We always used a 3lb mini sledge. You won't hurt the drums as long as you don't hit them real hard out on the lip.

[matthufham]

i'll try tomorrow definately. it wiggles but doesn't come off so i thought something might of been holding it back.

[Longhorn Man]

If the drums wiggle on the studs, then you probably need to back the shoes off.

[CHYNSPR]

Junkyardjohn, are you saying that the newer C-10 big brakes will bolt up to a '69 rear axle, or a '72 for that matter? ( I have both ).

[PICKMUP]

I think all 73+ PUs use the larger rear brakes. You just take the complete backing plate with all shoes, parts & drums and bolt it on your earlier model. It is a lot cheaper than rear disc systems and helps a bunch.

Same applies to 4x4 6lug trucks. We have been upgrading 1/2T 4x4 with this setup for a long time.

The only hassle is if you are junk yarding, you will have to pull the axles to get the assys off.

[junkyardjohn]

Originally Posted by CHYNSPR

Junkyardjohn, are you saying that the newer C-10 big brakes will bolt up to a '69 rear axle, or a '72 for that matter? ( I have both ).

YUP .. BUT YOU HAVE TO TAKE EVERYTHING TO & INCLUDING THE BACKING PLATE. A PRETTY GOOD UPGRADE FOR NOT ALOT OF $$$ JOHN

[cheyenne10]

Any reason the 6 lug 4x4 stuff wouldn't work on 6 lug 2 wheeler? Are these identifiable from the outside? (width of drum in inches?)

[krue]

That's good to know.

[69TowRig]

Hmm, maybe I'll do this instead of rear discs...

[jimfulco]

Not all of the later pickups use the wider brakes. I just junked an '84 that had the thin ones.

[matthufham]

my 72 c10 has 2 inchers, i finally got the drums off. thanks longhorn, loosened the star wheel all the way and it finally came off. didnt want to o back on but i got it done eventually.

[roger0080]

I belive those are the 11-5/32" drums, GM #14070351.

I have those on my 77 C10.

Best I can tell is that it is part of the RPO F44 HEAVY DUTY CHASSIS EQUIPMENT or else (?) comes with the HE4 REAR AXLE -3.40 RATIO option? from my SPID sticker.

[Steve Vos]

I have a 69 gmc with 72 front discs and the 11 5/32 rear HD drums on 5 bolt axles. The rear brakes came off a 73+ axle. They all bolted up to the rear housing great which is off a 70 and converted to 5 bolt. The problem I have is my pedal effort is too high and the stroke is too short compared to my 86 Silverado. I have good vacuum from the 396 engine. I used a 72 master and booster and a proportioning valve of unknown origin. I looks like the valve for an 81-87 Chevy listed on the inlinetube.com web site so I think that may be what it is. I also see these brakes listed in the 73-87 LMC catalog. In there they list different masters, proportioning valves, and boosters based on the larger drums. I am wondering if my setup is not correct. Does anyone out there know about this and what would work? Do I need to match the parts to these particular rear brakes? If I have to change boosters I would like to find a smaller dia to get more valve cover clearance. Any recommendations there?

Thanks in advance for any help.

[Hart_Rod]

I got mine off of a 71 Big block camper special. I think it was on the option code but not sure.

[ERASER5]

I wish I had found this thread a couple of months ago. Before I did all the research to find exactly what this thread is talking about. The only thing I could not find info on was the backing plate.

All was for naught. They don't make 6 lug big brake drums. At least I could not find them.

[ERASER5]

I reread pickemup's post. I did not think to look at 73+ 4X4 stuff. (slaps head)

[mbgmike]

Originally Posted by ERASER5

I reread pickemup's post. I did not think to look at 73+ 4X4 stuff. (slaps head)

pickmeups correct they used them even on the 6 cylinder versions