Advice on rear swap

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GrrageCat

GrrageCat

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Thanks for taking the time to give your opinion here.

I want to get rid of the 7 1/4 next year when I swap my slant for a 360. Mild street car.

I want to keep my SBP Cragars since I have new tires on and just did a disc brake conversion to keep the SBP on the front. (Scarebird)

A local seller has two rear options I can buy for a pretty good deal.

1. 8 1/4 out of a Duster. $150
- I think I can just get the drums and axles machined for the SBP right? Should be good to run after that. No need to modify spring perches.

2. 8 3/4 from an E Body. and he has SBP Axles to sell too. $100
- I would need to find someone and pay to get the housing shortened and also have the perches moved.

Trying to go the cheapest route here. Has anyone made an 8 1/4 drilled to SBP before?
 
Anything big bolt will have a larger center register on the axle so your small bolt wheels most likely will not fit. If you are stuck on the small bolt thing your best bet is the abody 8 3/4. Not cheap but may be the necessary evil.

Cutting a housing down to abody size works too but you'll need all the small bolt stuff to go with it. Axles, backing plates , drums and brake stuff.
 
Any idea how big the center register is on a 8 1/4? I can measure my Cragars and see how much space I have for it. Leaning towards option 1 if All i have to do is take the drums and axles to a machine shop to drill for the SBP. Seems it would be cheaper than to have the E Body 8 3/4 cut to size. I don't have much extra cash for this but want to jump on the deal before they are sold.
 
I don't remember what size it is. Sure someone here will know. It's a lot larger then small bolt axles though.
 
If you are going to have the bolt pattern changed, same shop can turn the center register down as well.

If it was up to me I would opt for an 8 3/4 from the correct years, breather hole location dictates, that way you don't have to remember that you have a 75 8 1/4 dart rear or a e body 8 3/4 cut down.

But like grragecat mentioned it is not cheap.

You will need (For either swap):
  1. Housing
  2. Center section
  3. Axles
  4. Backing plates
  5. Drums
  6. Spring peaches
  7. Correct U bolts
  8. Brake tubes
  9. Brake hoses
  10. Correct or modified driveshaft.
  11. U joints that match the centered section and transmission yokes

If you go with a cut down 8 3/4
  1. Cost to narrow.
  2. Spring perches
  3. Cost to streighten housing
  4. Cost for axles
  5. Maybe machining to change to SBP
If you go with 8 1/4

(Edit: It was pointed out that the 8 1/4 is a direct bolt in, headslap!)
  1. Cost to modify bolt pattern

Unless you can do most of the work yourself your looking at 1000 to 2000 regardless what you do. Perhaps a bit less for the 8 1/4 depending on what hardware you can get with it.

Simplest route is real A body 8 3/4 complete
 
Last edited:
Dana67Dart said:
If you are going to have the bolt pattern changed, same shop can turn the center register down as well.

If it was up to me I would opt for an 8 3/4 from the correct years, breather hole location dictates, that way you don't have to remember that you have a 75 8 1/4 dart rear or a e body 8 3/4 cut down.

But like grragecat mentioned it is not cheap.

You will need (For either swap):
  1. Housing
  2. Center section
  3. Axles
    Dana67Dart said:
    If you are going to have the bolt pattern changed, same shop can turn the center register down as well.

    If it was up to me I would opt for an 8 3/4 from the correct years, breather hole location dictates, that way you don't have to remember that you have a 75 8 1/4 dart rear or a e body 8 3/4 cut down.

    But like grragecat mentioned it is not cheap.

    You will need (For either swap):
    1. Housing
    2. Center section
    3. Axles
    4. Backing plates
    5. Drums
    6. Spring peaches
    7. Correct U bolts
    8. Brake tubes
    9. Brake hoses
    10. Correct or modified driveshaft.
    11. U joints that match the centered section and transmission yokes

    If you go with a cut down 8 3/4
    1. Cost to narrow.
    2. Spring perches
    3. Cost to streighten housing
    4. Cost for axles
    5. Maybe machining to change to SBP
    If you go with 8 1/4

    1. Cost to narrow.
    2. Spring perches
    3. Cost to streighten housing
    4. Maybe axles
    5. Maybe machining to change to SBP

    Unless you can do most of the work yourself your looking at 1000 to 2000 regardless what you do.

    Simplest route is real A body 8 3/4 complete
    Click to expand...
Click to expand...
(Pssst: The 8 1/4 he's looking at is already an A body unit out of a Duster- no narrowing, perches or straightening needed. Just pattern change.)
 
There have been a LOT of people run the little 7 1/4 behind 360s and they lived...and they gave them HELL. I'm not advocating for them, they are certainly light duty, but that's a fact.
 
Considering the cost/effort for the machine work, I'd grab that 8 1/4 and change it all to BBP. Any possibility of running lug pattern adapters?
 
Lots of aftermarket wheels do not have center registers.

Too many different OEM sizes.
 
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