7 1/4 width question....after searching

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69moredoor

69moredoor

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Looking at what 7 1/4 rears would fit in my valiant that are the same width...
So 64-72 are the same width (53” and change)

73 and later 7 1/4’s are slightly narrower? (51” and change)
Am I correct?
And all are small bolt pattern?
 
69moredoor said:
Looking at what 7 1/4 rears would fit in my valiant that are the same width...
So 64-72 are the same width (53” and change)

73 and later 7 1/4’s are slightly narrower? (51” and change)
Am I correct?
And all are small bolt pattern?
Click to expand...
73 and up, can be BBP if they came from a disc brake car. I don't know about the width difference.
 
The 7 1/4 A-body rear ends with small bolt pattern are all the same from '63 through '76 except for some of the brake parts. Now, comparing the small bolt pattern 7 1/4 with the big bolt pattern.......I don't know. I haven't done that measurement, but, I doubt there's much if any difference since they came with the same track specs.
 
The 73+ BBP 7.25" and 8.25" rear axle housings are 51.5" wide, which makes them 56 3/4" from wheel mounting surface to wheel mounting surface. Significantly narrower than the SBP 8 3/4 which are 57 1/8" and even more narrow than an A-body 8 3/4 that has been converted to BBP axles (57 13/16").

I am not entirely sure about the exact width of the SBP 7.25's. I've heard from multiple sources that you can't just swap the later 7.25" BBP axles into a SBP 7.25" housing to convert it to BBP. Based on what I've seen for tire clearances they're probably closer to the SBP 8 3/4 than they are to the BBP 7.25". But I've never had one to measure, my only 7.25" equipped car was BBP.

cudamark said:
The 7 1/4 A-body rear ends with small bolt pattern are all the same from '63 through '76 except for some of the brake parts. Now, comparing the small bolt pattern 7 1/4 with the big bolt pattern.......I don't know. I haven't done that measurement, but, I doubt there's much if any difference since they came with the same track specs.
Click to expand...

That's not an assumption I'd make. Given how different the BBP 7.25" and 8.25 are from the SBP 8 3/4 equipped cars there's no telling how different the track is. Even if the SBP 7.25" housings were the same as the BBP housings the track would be different because of the axle flange offsets (SBP to BBP 8 3/4 is different by 11/16").
 
72bluNblu said:
The 73+ BBP 7.25" and 8.25" rear axle housings are 51.5" wide, which makes them 56 3/4" from wheel mounting surface to wheel mounting surface. Significantly narrower than the SBP 8 3/4 which are 57 1/8" and even more narrow than an A-body 8 3/4 that has been converted to BBP axles (57 13/16").

I am not entirely sure about the exact width of the SBP 7.25's. I've heard from multiple sources that you can't just swap the later 7.25" BBP axles into a SBP 7.25" housing to convert it to BBP. Based on what I've seen for tire clearances they're probably closer to the SBP 8 3/4 than they are to the BBP 7.25". But I've never had one to measure, my only 7.25" equipped car was BBP.



That's not an assumption I'd make. Given how different the BBP 7.25" and 8.25 are from the SBP 8 3/4 equipped cars there's no telling how different the track is. Even if the SBP 7.25" housings were the same as the BBP housings the track would be different because of the axle flange offsets (SBP to BBP 8 3/4 is different by 11/16").
Click to expand...
I was only referring to the 7 1/4 rear axles.
 
I’ve got a SBP 7 1/4 you can have for free, if you want to come pick it up. I’m about to scrap it.
 
cudamark said:
I was only referring to the 7 1/4 rear axles.
Click to expand...

Right, but my point is that the A-body 8 3/4 already had a different track than the BBP 7.25 and 8.25. So why would you assume they’d be worried about the SBP and BBP 7.25’s being the same track?
 
72bluNblu said:
Right, but my point is that the A-body 8 3/4 already had a different track than the BBP 7.25 and 8.25. So why would you assume they’d be worried about the SBP and BBP 7.25’s being the same track?
Click to expand...
I didn't assume they'd be worried at all. I admitted I didn't know for sure about the measurement difference in the BBP vs. SBP rear axle assemblies. I've swapped them using the same wheel and tire size and had the same clearance in the wheel wells. Like I said, if there's a difference, it isn't much.
 
I found a BBP 7 1/4 with a 3.23 gear. But haven't bought it yet. The price is a bargain. But what I've gathered from this info is if I put a BBP 7 1/4 in place of my SBP 7 1/4, I will for sure have to get different wheels with a different offset , due to the wheel contact is now closer to the leaf spring and of course my wheels won't mount to the 5 on 4.5.
 
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