70 coronet 8.75 in 70 dart

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V8 Sam

V8 Sam

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So, I'm trying to get things straight in my head this. Been reading about this axel swap and have recently got the option of buying a decent 1970 coronet B-body 8.75 sure grip axel(very few and far between here)

I have also read that that b body axels (especially the earlier ones due to being even narrower) fit better into the duster/demon/sport type bodies due to the wider wheel arches.

But what about the '70 swinger type bodies?

I wish to maintain my SBP cop steel 14 inch wheels.

In order to do this as far as I'm aware you need to narrow down the '70 b body axel, fit the appropriate a body half shaft and move the spring perches in.

Is anyone able to tell me how far in the perches need to be moved? ( Half an inch I believe?)

And how much the axel needs to be shortened either side?

Once the axel is narrowed and perches are moved in, would i then be able to use my current wheels with our having to get anything custom built in order to comply with back spacing issues. Correct?


Then have the drive shaft shorted to fit for the new axle and away we go?

The current 7 1/4 and V8 with manual box combination is providing to be to much for the axel and I don't want to break it if I can help it, hence the swap. Also making it s bit livelier in the process can't hurt!:lol:

Obviously I'd like to find a body one but over here in London UK they are extremely hard to find haha


Thanks in advance.
 
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You are in the right direction...

If you want to keep your SBP you would need to get some A body axles or have custom made axles. IIRC only A bodies used the SBP everything else used the BBP.

Thr perches would need to be moved inboard 1/2 inch each side.

The backing plates need to match the axles, A body has a different back space than the rest. So if you go cut down axles you need the backing plates that came with it,

Unless you are going to do the cutting and welding, narrowing and resplining yourself, I think even with shipping to the UK buying the parts used or from DR. Diff to get matched SBP A Body housing, brakes, and axles would end up being cheaper
 
I should say that I have also been offered sbp a body half shafts from a chap here in the UK who upgraded his to BBP so these are spare. (He will measure these over the weekend just to double check)

Hopefully it would mean just changing to 4.5 axels when/if the time ever comes up upgrade to BBP.

The '70 coronet axel is question dosnt come supplied with any brakes. It's the only thing missing.
 
At this point. If you narrow the B body housing to the correct A body width, moved the spring perches, and used the A body axles. The only things you would need to get would be A body 8 3/4 backing plates and drums. The center section will swap in no problem
 
Forgot... You will also need u bolts and shock plates for your 8 3/4 the 7 1/4 won't fit
 
I have an old a body 8.25 down the side.of my garage, it's very tired though hence.why I'm.not using it. Are the back plates interchangeable between the 8.25 and 8.75?

3 inch u bolts I have new!

Shock plates will come off the 8.25,.so no issue there either

Do you know how much either side needs to be narrowed on the 70 b body one so I can let the machine shop know.

As they have asked me to provide measurements, I have no way of cutting and welding properly at my garage.
 
V8 Sam said:
I have an old a body 8.25 down the side.of my garage, it's very tired though hence.why I'm.not using it. Are the back plates interchangeable between the 8.25 and 8.75?

3 inch u bolts I have new!

Shock plates will come off the 8.25,.so no issue there either

Do you know how much either side needs to be narrowed on the 70 b body one so I can let the machine shop know.

As they have asked me to provide measurements, I have no way of cutting and welding properly at my garage.
Click to expand...

Yes, I believe the backing plates interchange. The measurements for the spring perches are 43" from center to center and centered on the housing. If you want to narrow it, I believe the correct width is 52 5/8 flange to flange if I remember right.
 
Dana67Dart said:
At this point. If you narrow the B body housing to the correct A body width, moved the spring perches, and used the A body axles. The only things you would need to get would be A body 8 3/4 backing plates and drums. The center section will swap in no problem
Click to expand...

And if this is all done and correct I should have no issue with wheels providing they are the correct bolt circle?

And obviously not MASSIVE etc.
 
Here are measurements right off an A Body 8 3/4 housing. (RRR has a good rememberer!)

Lastly be sure the shop maintains the OEM pinion angle and streighten the housing after the welding.

NOTE: in the last photo, I can not stress it enough.

USE FACTORY LIKE U BOLTS. TIGHTEN ONLY TO FACTORY SPECS.

Most aftermarket u bolts do not have the flat at the top of the U like factory do and can apply enough point load to crush the tube.
This is the correct factory U bolts.
IMG_20200728_131427.jpg


16009642845011370151961263483417.jpg
16009642968283709136625921078341.jpg
1600964332458904606526426051546.jpg
16009643790432696961185344548973.jpg
 
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