A body BBP axle length for 8 3/4"

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92b

92b

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Does anyone have access to an OEM A body 8 3/4" rear end BBP axle that they could measure the length of? Measurement from side of flange where the wheel bolts on to tip of splined end of axle. Stand axle on the floor straight up with splined end down. With tape parallel to the shaft measure from floor to surface where wheel bolts up. Thank you.
 
Yukon brand was different..it allowed you to reuse your small bolt drums just drill new 4.5 pattern on them....the other brands required different backing plates ffg or BBP
 
92b said:
Does anyone have access to an OEM A body 8 3/4" rear end BBP axle that they could measure the length of? Measurement from side of flange where the wheel bolts on to tip of splined end of axle. Stand axle on the floor straight up with splined end down. With tape parallel to the shaft measure from floor to surface where wheel bolts up. Thank you
Click to expand...
What exactly are you trying to accomplish
 
All these guys telling you there is no such thing as a OEM a-body 8 3/4 bbp axle, are right.
There are bbp 8 3/4 a-body axles but they are aftermarket, and usually require b-body brakes, drums, and backing plates. The offset from the wheel mounting flange to the backing plate is different on an a-body 8 3/4 from all other 8 3/4s because of the small thin brake shoes.
 
If nobody gets to it before me, I can get this measurement for you tomorrow. I have a set of original 8-3/4 axles, SBP that were re-drilled with new studs welded in to make them BBP.

Be aware, if you decide to go aftermarket for a set of new BBP axles, the ones from Dr. Diff are excellent, but they are a bit wider than the stock ones. If you are super-tight on your wheel/tire/backspacing/fender clearance/etc it can rain on your parade. Ask me how I know...
 
Great info thanks everyone. This is clearing things up for me. I have a 8 3/4 rear end for a 69 a body and would like to convert it to BBP. I have some BBP axles that are long enough and large enough in diameter to be cut down to proper length and resplined. I also have a 8 1/4" donor for the brake hardware. I'm unsure what proper length is since the bbp axles are off set more between the bearing flange and the wheel side of the flange. If the chart on the sticky and my math are correct I think the axle will need to be 11/32" longer than a SBP axle. This is how I came up with 11/32.
According to the chart all A body housings are 52 5/8" wide. SBP rears measure 57 1/8" drum to drum. BBP rears measure 57 13/16". A difference of 11/16" total. One axle would be 1/2" the total or 11/32". So if a SBP axle is 27 11/16" then would my axle need to be 11/32" longer or 28 1/32"?
All that said I did not know there was an axle you could buy with BBP that you could use with SBP drums that is the correct offset between the bearing and wheel flange. Sounds like you just slot or re drill the drum to fit? Yukon brand? Does anyone know the part number for this axle? This might be an option instead getting axles resplined. Thanks everyone for the help.
 
In all reality the distance from the inside of the bearing to the end of the spline is the measurement you need.

Regardless of cut down and resplined BBP axles or redrilled SBP axles the only diference will be that the BBP axle will need B, C, or E body backing plates and drums and the SBP will need SBP backing plates and drums.

I assume (and we know what happens when we assume) that 8 1/4 brake backing plates and drums are the same as B, C, and E body parts.

The overall distance from flange to flange will change between SBP and BBP axles due to the diference in the wheel flange to bearing spacing.
 
Use 1984-1989 M body brakes from backing plate out. They are 10x2.5" finned drums. The backing plates will bolt to the 8&3/4 rear axle. Dr Diff has BBP A body axles. Ask me how I know all this.
 
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