8 3/4 small pattern to large pattern swap, what drums???

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604

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What drums are people using when they change there A-body 8 3/4 over to the large wheel pattern? I think mine has the factory 10 by 1 3/4 small pattern drums on it right now. Thanks!!!
 
I used 11" cop car rear ones on my Valiant. Remember that you need the matching backing plate too, the sbp ones are different than the bbp ones.
 
You will have to use either 10 1/2 0r 11" the 10 1/2" is more readily available. I got the drums new at Autozone for like $39 each.
 
Thanks!
If that is the case I will have to stick with the small pattern axles. As I have drums in the front "soon to be 10in" I do not want bigger ones in the rear. And have no intention of changing to a disc front. I wonder if I can just have my small pattern drums redriled for the larger pattern???
 
Get ANY big bolt pattern drum/backing plate combo. Dana 60, 8.75, 7.25 and 8.25 all use the same parts for BBP. If you see a car in the boneyard with rear brakes on it and BBP, grab them.

The axle standoff distance is different from sbp to BBP. You can't swap or redrill your current drum. Additionally, the centering hole is smaller diameter on the SBP drums than the BBP
 
And they will be 10" or 11", not 10.5.

And like crackedback said, grab everything. Backing plates, drums, shoes, hardware, etc. Many parts you will want to replace, but some are not available new. If you get everything off of a donor car, you won't end up missing stuff.
 
or you can order the axles to use your current brakes and just redrill or slot the holes
thats what we did for the kids car since he had all new brakes on the back.
 
vitamindart said:
or you can order the axles to use your current brakes and just redrill or slot the holes
thats what we did for the kids car since he had all new brakes on the back.
Click to expand...

This is correct. It all depends on what axles you buy for your bbp conversion.
I ordered axles from Moser, and they asked if I wanted bbp offset, or sbp offset.
I got the sbp offset axles, then used my existing brakes, and just redrilled the larger pattern on my drums myself. Its not difficult. And as far a the size of the centering hole on the axles/drums, the center hole on my sbp drums was an exact fit to the center bump on the new axles.
To mark for the new holes, I just set the drums on the new axles and marked through the lug holes on the axle. (the studs werent installed yet). Just remember when you drill the drums, the studs are 1/2", but the knurled part of the stud sticks out of the axle enough to engage the lug holes in the drum. So you have to have a drill bit thats just a little bigger than 1/2"


Good luck
 
Great to know! Thanks!!!

MileHighDart said:
This is correct. It all depends on what axles you buy for your bbp conversion.
I ordered axles from Moser, and they asked if I wanted bbp offset, or sbp offset.
I got the sbp offset axles, then used my existing brakes, and just redrilled the larger pattern on my drums myself. Its not difficult. And as far a the size of the centering hole on the axles/drums, the center hole on my sbp drums was an exact fit to the center bump on the new axles.
To mark for the new holes, I just set the drums on the new axles and marked through the lug holes on the axle. (the studs werent installed yet). Just remember when you drill the drums, the studs are 1/2", but the knurled part of the stud sticks out of the axle enough to engage the lug holes in the drum. So you have to have a drill bit thats just a little bigger than 1/2"


Good luck
Click to expand...
 
if you're interested I have BBP A body 10x2.5" drum brakes for sale I'm using B body rear axle/brakes so I don't need these
 
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