8.75 Brakes

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Projectile Dart

Projectile Dart

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Recently got a hold of a low mile (60K) 8.75 from a '72 Dart. Brakes are going to need a rebuild but the rear end is still currently SBP and eventually I would want it to be LBP. I was planning on just rebuilding the brakes and running it SBP for now and upgrading to LBP in the future when I have the $$ for a suregrip unit to install at the same time of swapping the axles.
Are the internals of the drums and drum backing plates identical between SBP and LBP? Or would I be better off getting internal parts specific for a LBP car such as a '73 A-body or different model of Mopar?

8.75.jpg
 
IF you redrill the factory drums and I believe keep the axle offset the same, yes.
IF you use the B-body 10" brakes and drums, some is and some isn't.
IF that makes sense, you are a better person than I.
(look at Rock Auto to see what parts would swap).
 
SBP axles have a different flange to bearing spacing than LBP axles

replace backing plates and axles with LBP (best choice if you change to LBP IMHO)
 
You will be open to many options after you switch to the new axles so I wouldn't buy anything for the new set up till you have what you are actually using in hand...
 
For a streeter, the SBP is fine.
To fit the widest tires you can into a Dart wheelwell, you will need a custom offset wheel, so you might as well stick with the SBP and buy a custom 15"wheel.
If you upgrade to an 8.75 with an LBP , your track will change, and you will need new custom offset wheels, again.
So, IMO, make your decision once, make it today.
IMO, for a streeter Dart, the BBP is a luxury you don't really need, no matter what engine is under the hood; the sbp is not your weakest link.

Having said that, if you have your heart set on a certain wheel that only comes in a bbp, well there is no good argument against that; I did it to myself,lol.
To use the bbp, I had to get get a C-body rear, and narrow it (and shorten the axles) to my specs. This got me the correct backing plates and matching drums, as well as the 7290 yoke.
My other option was to redrill the axles and the drums, but as you can see in your picture, I didn't think much about that. and the end result is that your bbp wheels will not center on, and be supported by, the hub of the sbp axles.
If you order custom axles,
#1) the flanges will be further out, making your track wider. No big deal except your shoes will end up not inside the drums. So
#2) you will have to either get different backing plates or fabricate spacers to push your backing plates back inside the drums, and
#3) you still have to deal with the larger wheel-register not fitting into your drums. and
#4) now you are stuck buying a new set of custom offset wheels,...... again.

Hyup I learned the hard way. That was 2004 I think, long before I heard of FABO. Long before I even had a computer,lol.
 
Last edited:
AJ/FormS said:
For a streeter, the SBP is fine.
To fit the widest tires you can into a Dart wheelwell, you will need a custom offset wheel, so you might as well stick with the SBP and buy a custom 15"wheel.
If you upgrade to an 8.75 with an LBP , your track will change, and you will need new custom offset wheels, again.
So, IMO, make your decision once, make it today.
IMO, for a streeter Dart, the BBP is a luxury you don't really need, no matter what engine is under the hood; the sbp is not your weakest link.

Having said that, if you have your heart set on a certain wheel that only comes in a bbp, well there is no good argument against that; I did it to myself,lol.
To use the bbp, I had to get get a C-body rear, and narrow it (and shorten the axles) to my specs. This got me the correct backing plates and matching drums, as well as the 7290 yoke.
My other option was to redrill the axles and the drums, but as you can see in your picture, I didn't think much about that. and the end result is that your bbp wheels will not center on, and be supported by, the hub of the sbp axles.
If you order custom axles,
#1) the flanges will be further out, making your track wider. No big deal except your shoes will end up not inside the drums. So
#2) you will have to either get different backing plates or fabricate spacers to push your backing plates back inside the drums, and
#3) you still have to deal with the larger wheel-register not fitting into your drums. and
#4) now you are stuck buying a new set of custom offset wheels,...... again.

Hyup I learned the hard way. That was 2004 I think, long before I heard of FABO. Long before I even had a computer,lol.
Click to expand...

Thank you for your input, this information is extremely useful
as far as SBP vs BBP... The front is already running BBP disk brakes with 17" wheels so I am already committed to the switch. A major factor for wanting to do the switch is the availability of aftermarket options for wheels without needing for them to be custom made.
As far as everything else, if making the switch and keeping the backing plates is as easy as making a spacer then that is no issue for me. My only problem is that the flange doesn't look like it has much space to offset the BBP into it while also keeping enough meat to keep everything supported. Another big concern of mine is not being able to nail the BBP redrill dead center and having it cause a vibration which would likely kill bearings and brakes faster along with another list of issues which is why I was strongly leaning towards new axles (most likely Dr.Diff)
 
Projectile Dart said:
not being able to nail the BBP redrill dead center
Click to expand...
And with the hub no longer centering the wheel, I'm with you.
If you are not trying to fill up the rear tub with tire, then have at it. The problem only comes up when you are trying to fit a fat tire in there. Then you will come to find that (maybe, most likely) you cannot find an off the rack wheel with the backspace that you need.

That's when the trouble starts.
And if you are already committed to a certain wheel, then it could get expensive.

And if you have a 360, you just can't put enough rubber back there.
 
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