SBP to BBP rear drum change

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moparfanatic56

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I am going to change my 8.75 rear axles from sbp to bbp. When I do can I just switch the drums to bbp as long as they are the same size or do I need to change everything ie backing plates, drums, shoes ect. Any help will be appreciated. Thank You
 
Re-drill the drums..they will have 10 holes when done
 
Well when I installed my Yukon axles I just redrilled my drums like I have for years...works perfect!!
 
I am aware the axle sits out farther with big bolt axles also
 
Centers have to be cut with lathe to accept dia..of new axles
 
I am going to change my 8.75 rear axles from sbp to bbp. When I do can I just switch the drums to bbp as long as they are the same size or do I need to change everything ie backing plates, drums, shoes ect. Any help will be appreciated. Thank You

Everything must be changed. The BBP axles have a different flange offset than the SBP axles. If you're installing true BBP axles then you will need 10x2.5" drum backing plates, drums, etc.

Well when I installed my Yukon axles I just redrilled my drums like I have for years...works perfect!!

That's because Yukon makes axles that use the SBP flange offset with the larger bolt pattern. With those axles you can only use redrilled SBP drums, you can't use the 10x2.5" BBP drums.

You can't mix and match. If your axles have the SBP axle flange offset, regardless of the actual bolt pattern, you must use SBP brakes and redrill them to whatever pattern you have. If your axles have the BBP flange offset, you must use BBP brakes.
 
Dr. Diff can get you special axles and re-drill drums, and keep original backing plates brakes etc. I have done it twice.
 
Dr. Diff can get you special axles and re-drill drums, and keep original backing plates brakes etc. I have done it twice.

If you do this, you're stuck buying the SBP 10x1.75" drums and re-drilling them every time they have to be replaced.

While the SBP drums are currently available, they've gone out of production several times in the past. You're much better off just using BBP axles with standard BBP axle flange offset. The BBP, 10x2.5" brakes are usually pretty easy to find used. You can even use 11x2.5" brakes if you want some more stopping power back there.
 
Why do people risk there lifes to save a few dollars? Glad he went the correct route.
 
I have the 8.75 rear end and converted to the larger 1970 Charger rear backing plates and hardware. Between that and the Wilwood disks in the front it's a huge improvement in stopping power.
 
If redrilling the drums is such a bad idea why in the world would Yukon and Moser offer a kit......use your brain!!!
 
If redrilling the drums is such a bad idea why in the world would Yukon and Moser offer a kit......use your brain!!!

Ok, let’s use our brains. Yukon doesn’t sell brakes at all. Moser’s only Mopar brake package is just a Wilwood disk kit, so they’re just making wholesale. Neither one of them sells drums, so regardless of which axle you buy they still make their money.

And it’s not really that it’s a “bad idea” or that you’ll have “issues” with re-drilled drums. Re-drilling the drums isn’t dangerous if it’s done correctly. Performance wise the 10x1.75” brakes are ok, it’s not that they’re dangerous or anything either. Using those SBP offset axles just locks you into buying small bolt pattern drums and then paying to have them re-drilled every time you need new drums. With as little as most people drive these cars that’s probably only a one time deal, sure. But some of us drive our cars enough that we could be replacing the drums a few times. And the small bolt pattern drums have fallen out of production a couple of times, there was a stretch of time not that long ago where you couldn’t get reproduction small bolt pattern drums, so for like a year or more if you needed a SBP drum you had to go on eBay and either buy a used drum you hoped could be turned or pay ridiculous NOS prices. There are several threads on here that talk about that.

The SBP drums only came on A-bodies. The BBP drums came on just about every RWD Mopar until 1989. So, which do you think is easier and cheaper to find parts for? If you’re already replacing the axles, it just makes sense to use the BBP drums too. Better and cheaper parts availability, parts work straight off the shelf and you get (slightly) better braking too.
 
Anyway I like my stock bell drums for my 71 duster...period correct and yes a hens tooth..that's one of those parts that you just buy everytime you see them when they are salvageable ...never had a problem with the drums and I own 10 abodies...half are done this way with 10 holes..that's the truth even if it's not your way!!
 
Anyway I like my stock bell drums for my 71 duster...period correct and yes a hens tooth..that's one of those parts that you just buy everytime you see them when they are salvageable ...never had a problem with the drums and I own 10 abodies...half are done this way with 10 holes..that's the truth even if it's not your way!!

Just seems like a completely unnecessary aggravation to me. Not all of these cars even came with the "bell" drums, even from the factory. And the 10x2.5" regular drums don't look all that different from the non-bell drums, especially hidden behind a set of factory wheels. Crap load easier to just deal with the BBP drum swap up front and then be able to buy new drums at the local parts shop and slap them on without any additional work or machining. Plus all of the parts are easier to find and cheaper, no hunting around or buying used drums when you find them to stockpile to keep your car on the road.

If "correct" is an issue then the car should stay SBP anyway. And run 14's with skinny tires. And if that's the case the SBP rear drums are fine, not enough tire to need more anyway. But as soon as you start upgrading, or frequently driving the car, the BBP brake and wheels should be first on the list of things to do IMO. Like I said, re-drilling the old drums isn't a safety thing, it's just a hassle. And if you're buying new axles, why lock yourself into that hassle when it's just as easy to go with the later brakes? A couple of brake jobs later and they'll have paid for themselves compared to staying with the SBP stuff and re-drilling.
 
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