Rear Drum Help. Big Bearing need drums

[lgdpt]

I purchased a (big bearing) rear end a few years ago. I was told it was from a 77 Bronco. It lines up and went together perfectly. However, I need to replace the drums on it but cant figure out what they are....

Oreillys keeps giving me drums that are too "deep". They are 11" and match up with my wheels/lugs but are not right for my rear end. I think 75 and earlier are 10" so that wont work....

Any suggestions on what rear end I could have? Or what drums to try?

My old drums are stamped FOMCO 86633 but I cant find anything online.

 

[Broncobowsher]

The earlier housings were small bearing with 10" brakes and the big bearing got the 11" brakes.

The '77 has a distinct center section from the '76 and prior. Where the tubes are welded to the center there is a lot more reinforcement. Typically known as a big banjo housing. Check that to see if you actually have a '77 housing.

 

[lgdpt]

The earlier housings were small bearing with 10" brakes and the big bearing got the 11" brakes.

The '77 has a distinct center section from the '76 and prior. Where the tubes are welded to the center there is a lot more reinforcement. Typically known as a big banjo housing. Check that to see if you actually have a '77 housing.

Nope, nothing welded to it. If its laying down on a bench its 3" tall. Inside (contact with shoe surface) is 2" deep.

 

[lgdpt]

So I guess I didnt know there is a 66-75 big bearing and that is what I must have. Thank you!

 

[EPB72]

And I think the brake shoe width is different 1 3/4 in for earlier to 75 and 2 1/4 inch76 and 77

 

[lgdpt]

And I think the brake shoe width is different 1 3/4 in for earlier to 75 and 2 1/4 inch76 and 77

Got it. thank you!

 

[DirtDonk]

And the axle shafts are different offsets as well, so it it definitely good to know what you have now.
The backing plates are made of hen's teeth though, except for the big '76 and '77 models described above. So take care of the originals as long as you can.

Got a pic of this differential housing?

Paul

 

[Timstrk]

Three years in the mid-70s had big bearing with 10" drums. The medium duty 9" rear. My Ranger has that. The shoes are wider but not as big in diameter.

 

[Jfryjfry]

I have a pair of drums that are in good shape I’d let go cheap if you’re interested. I believe they are the ones you want. I’m by lax. Drop me a pm here if so!

 

[lgdpt]

I called WH's and they think they have what I need.... Hopefully they arrive today. If they dont work, I will post a pic for you Paul. And I will reach out to you Jfryjfry.

Thank you all

 

[BoulderMike22]

Did you end up figuring out which drums replaced the FOMOCO 86633? I had drums that were on my Bronco but did not seat fully against the backing plates. A buddy had the 86633 which fit perfectly and I have been unable to find a part number to order a set.

The brakes are 11" x 1.75" from the earlier big bearing/big brake housing but you can tell from the picture that the one I need allows the backing plate to sit inside of a groove of the drum whereas the one that every parts place seems to carry just has the one with a lip .

The one on the right is the correct style that I can’t seem to find. Every parts store has the one on the left?


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[gr8scott]

These look like the one on the right.

https://www.napaonline.com/en/p/ND_4401455

 

[BoulderMike22]

These lokk like the one on the right.

https://www.napaonline.com/en/p/ND_4401455

Those are too tall. The later model brakes were 11” x 2.25” I believe. The 75 and earlier big brakes were 11” x 1.75” so a full half inch narrower on the brake contact surface area.


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[gr8scott]

Maybe call WH and see what their's look like... calling @DirtDonk

Or Dennis Carpenter?

https://www.dennis-carpenter.com/tr...MI1Oz0nPj4gAMVyDHUAR1iPAnHEAQYBSABEgLIafD_BwE

 

[Viperwolf1]

Those are too tall. The later model brakes were 11” x 2.25” I believe. The 75 and earlier big brakes were 11” x 1.75” so a full half inch narrower on the brake contact surface area.


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Those Dennis Carpenter ones look right. I have an old Federal Mogul part number, BD60052, that might cross over to something current.

 

[BoulderMike22]

I did call WH and explain my situation. They gave me their part number but weren’t much more help than that. Called Tom’s and sent them multiple pictures and measurements. They were great and sent me actual pictures of the drums they had. Their drums are the same as the aftermarket ones I have already (on the left). I measured the brake shoes and the wear pattern on both sets and they are the same but the FOMOCO is centered and clearly designed to create somewhat of a seal to keep grime and junk out.

My thought is the aftermarket molds eliminated the groove/pocket because it was easier to make.

The Dennis Carpenter picture is impossible to tell whether the back side or profile is correct. From the top- both of them look the same. I will reach out to DC and see if I can send them pics of the 2 and have them possibly confirm before ordering anything.

Appreciate the responses!


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