Brake Drum Question

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moparspares

moparspares

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Are the 1970 - 1972 10" rear brake drums the same as 1973 - 1976 10" drum except for the bolt pattern.

I have a 8/34 71 rear end in my 73 duster but want to replace the axles and rear drums for the later set up. Wil they be a direct fit?
 
No. Bolt pattern, width as well as the drum "register" (round raised circle in the middle that centers it) is all different. Backing plates have a different offset to work with everything as well.

You can get an aftermarket axle company to machine your replacement axles with a 4.5" pattern to fit your existing drum set-up. But then the drums would need to be redrilled as well for a 4.5" pattern.

Typically, E, B and many F/M/J body brakes are swapped in and the axle manufacturer is asked to machine A-body length axles using B-body brake assemblies.

(I hope I covered all the bases.)
 
Bummer!! It could never be just as easy as swapping axle and drum could it. Ah well to the local machinest we go.
 
Cass at Dr Diff can set you up with axles that are ready to bolt in. Then you just need the backing plates, shoes, brake hardware and drums off any 5 lug 8 1/4 rear end and you will be set. Other rear end brake set up may also work, I am not sure. The 7 1/4 backing plates will not work.


http://www.doctordiff.com/
 
Get your new large bolt pattern axles from DrDiff. I just installed a set and couldnt be more pleased.
You can use virtually any rear brakes from any 5 on 4.5" bolt pattern MOPAR rear, 1965 and up.
I've got a couple sets of 10"x2-1/2" rear brakes that will work.
 
Ordered my axles from Moser for the 5 x 4 1/2 bolt patteren for my 8 3/4 out of a 70 dart and unbolted brakes from my 76 7 1/4 and they bolted right on. Been fine for 15 years. BITE THE BULLET AND GET GOOD AXLES.
 
Oklacarcollecto said:
Cass at Dr Diff can set you up with axles that are ready to bolt in. Then you just need the backing plates, shoes, brake hardware and drums off any 5 lug 8 1/4 rear end and you will be set. Other rear end brake set up may also work, I am not sure. The 7 1/4 backing plates will not work.


http://www.doctordiff.com/
Click to expand...

Cass is definitely the guy to talk to! :thumbup:

BUT, 7 1/4 backing plates WILL work if they're from a 5x4.5" pattern 7 1/4. In fact, any 5 x4.5" pattern 10" or 11" rear brakes will work with BBP axles, the axle offset is the same for all of them. Any 5x4.5" bolt pattern 10x2.5", 11x2", 11x2.5" or 11x3" brakes will work with BBP axles. They can be from a 7 1/4, 8 1/4, 8 3/4, Dana 60 or 9 1/4" rear end as long as they've got BBP axles.

The only other wildcard is using the 11" brakes, the backing plates have to be matched with the drums and shoes because the backing plate offset is different so that they all work with the same axles. Ie, you can't put 11x2.5" shoes and drums on 11x2" backing plates.
 
72bluNblu said:
Cass is definitely the guy to talk to! :thumbup:

BUT, 7 1/4 backing plates WILL work if they're from a 5x4.5" pattern 7 1/4. In fact, any 5 x4.5" pattern 10" or 11" rear brakes will work with BBP axles, the axle offset is the same for all of them. Any 5x4.5" bolt pattern 10x2.5", 11x2", 11x2.5" or 11x3" brakes will work with BBP axles. They can be from a 7 1/4, 8 1/4, 8 3/4, Dana 60 or 9 1/4" rear end as long as they've got BBP axles.

The only other wildcard is using the 11" brakes, the backing plates have to be matched with the drums and shoes because the backing plate offset is different so that they all work with the same axles. Ie, you can't put 11x2.5" shoes and drums on 11x2" backing plates.
Click to expand...


So noted and thank you.
 
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