8 3/4 B to A swap

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ArizonaKid

ArizonaKid

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I have an 8 3/4 rear end out of a '73 satellite that i want to use in my dart and i was wondering about the costs and transfers involved in such.

How much do i have to shorten the rear end? how much is it going to cost? where do i have to relocate the spring mounts? Will i have to change other stuff, like the driveshaft and the parking brake cables?

And finally, does anyone know anybody in the boise (or southern idaho) area that has the equipment to do this? nobody i know has needed to do this, so i have no leads at all.
 
I believe the housing is 3-1/4" too wide if my information is correct. The spring perches will have to be moved in to 43" center to center. Cost is area dependent. Costs me about $250 to get a housing and axles shortened but I've heard guys in other states say it's up to $400 where they live. Due to having to buy different axles (you can't shorten B-body axles to a-body length because their tapered down right after the splines) it'll most likely cost more to have it done than buying an a-body setup.

Not sure on the parking brake cables but you will have the change the driveshaft if the rear in the car now is anything other than an 8-3/4
 
What year Dart is it going in? People put earlier B-body axles in A-bodies without shortening them quite often. The wider axle allows them to run a wider wheel/tire with a more modern offset wheel. Thats the route I'm going.
 
Mopar 8 3/4" Rear End Dimensions

........................................
........................................

8 3/4" axle shaft lengths measured from the tip of the splined end
to the outside of the flange:

A BODY
'66-'72= 27 11/16"

B BODY
'65-'67= 28 7/8"
'68-'70= 29 3/16"
'71-'74= 30 5/8"
'71-'73 wagon= 31 21/64"

C BODY
'65-'69= 30"
'70-'71= 30 5/8" (Chrysler & Fury)
'70-'73= 31 21/64" (and '69 wagon)


IMPERIAL (Large Bolt Pattern)
'65-'66= 30 1/8"
'67-'69= 30 5/16"
'70-'71= 29"
'72-'73= 31 7/16"

E BODY
'70-'74= 29 31/32"

A100
'65-'70= 30"

D100
'65-'71= 31 1/8"
'72-'74= 31 21/64

...........................................
...........................................

Housing widths, flange to flange

A BODY
'66-'72= 52 5/8"

B BODY
'62-'63= 53 1/4" (And '64 Max Wedge)
'64 = 55 5/8" (Exc. Max Wedge)
'65-'67= 54 1/4"
'68-'70= 54 15/16"
'71-'74= 57 7/8"
'71-'73 wagon= 59 7/16"

C BODY
'65-'69= 56 3/4"
'70-'71= 57 7/8" (Chrysler & Fury)
'70-'74= 59 7/16" (and '69 wagon)

IMPERIAL
'65-'66= 57"
'67-'69= 57 3/8"
'70-'71= 54 3/4"
'72-'73= 59 5/8"

E BODY
'70-'74= 56 31/64"

A100
'65-'70= 56 3/4"

D100
'65-'71= 58 5/16"
'72-'74= 59 7/16"

.........................................
.........................................

Rear end widths, drum-to-drum:

A BODY
'66-'72= 57 1/8"

B BODY
'62-'63= 58 1/2" (And '64 Max Wedge)
'64 = 60 7/8" (Exc.Max Wedge)
'65-'67= 59 1/2"
'68-'70= 60 1/8"
'71-'74= 63"
'71-'73 wagon= 64 3/8"

C BODY

'65-'69= 61.75"
'70-'71= 63.0" (Chrysler & Fury)
'70-'73= 64 3/8" (and '69 wagon)

IMPERIAL
'65-'66= 61 15/16"
'67-'69= 62 5/16"
'70-'71= 59 3/4"
'72-'73= 64 9/16"

E BODY
'70-'74= 61 5/8"

A100
'65-'70= 61 3/4"

D100
'65-'71= 63 15/16"
'72-'74= 64 3/8"

........................................
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Spring perch widths (center-to-center)

A BODY
'66-73= 43"

B BODY
'62-'70= 44"
'71-'74= 47.3"

C BODY
'65-'73= 46"

E BODY
'70-'74= 46"
 
Yeah, it's off. The info that Joe posted is correct, probably form the same site, lol.
 
To summarize what's already been said, the best B body rear to use in an A body is the 65-67 B body rear, followed by the 68-70 B body rear which is roughly 1/4 inch wider.

Even the 68-70 is only 3 inches wider which translates to 1 1/2 inches in extra width on each side.

More importantly, the center to center width on the spring perches is 44 inches as opposed to the 43 inches on stock A bodies. That's 1/2 inch on each side.

Some people move the spring pads in 1/2 inch. I do not. If you pull sideways slightly on the leaf springs, the 44 inch spring seats wil drop right down on the tabs. The 66-70 B body housing is virtually a bolt in swap.

You could be way ahead of the game both financially and stress wise to sell your 73 housing and buy a 66-70 B body instead.

This may help you as well:
http://www.moparmusclemagazine.com/techarticles/drivetrain/mopp_0404_8_3_4_rear_axle_housing_swap/viewall.html

(although from experience I would dispute the need to move the spring seats or enlarge the holes)


Good Luck!
 
I have a b body rear end in mine.

I moved the spring perches in on mine and went to a 5.25 Backspacing wheel.

No cutting of the housing or axles.. Nice 245/60 tire under it now.


Bruce
 
Bad Sport said:
I believe the 71 to 74 is going to be 5 1/4" wider. A 68 to 70 would be the 3 1/2" wider
Click to expand...

Your right. I have the correct chart but somehow figured wrong

To the OP. What ever rearend you use I suggest making sure the spring perches are on 43" centers. I've heard of guys spreading the springs but stop and think what your doing. Your putting all the bushings in a bind so their going to wear out a lot quicker.
 
fishy68 said:
To the OP. What ever rearend you use I suggest making sure the spring perches are on 43" centers. I've heard of guys spreading the springs but stop and think what your doing. Your putting all the bushings in a bind so their going to wear out a lot quicker.
Click to expand...


Some folks do that, I always wondered why Ma Mopar didn't do it, lol.
 
DNasty777 said:
What year Dart is it going in? People put earlier B-body axles in A-bodies without shortening them quite often. The wider axle allows them to run a wider wheel/tire with a more modern offset wheel. Thats the route I'm going.
Click to expand...

A 1974 dart 2 door hardtop.

That might work, if I wasn't planning to run original magnums, i have a good set and cant afford to go and buy new wheels.
 
I put a 68 B body in a 74 Duster. Moved the spring perches in. It looks like it was made for it, but on a Dart or other car with a lower wheel opening, things will get tight. With a proper offset wheels it is no problem, but you have to put a little thought and effort into it to get everything looking right.
 
Is there a 'correct' chart like the one shown above with 7.25 and 8.25 info? I have a 73 swinger with V8 and 8.25 That I want to put in a 69 barracuda. Before I order some LBP wheels, Id like to know if there are any differences..
 
I have a 62 Dart with an 77 cop rear end in it with the steel wheel that are 5" off set.
My 275 60 r15 will work on them, but the American racing with 4.5 won't. I have a 65 with a 323 sure grip I'm going to have cut to make it fit. If anyone has the right rear end and want to do some trading I'm here.
Thanks
 
I figure I should put out more information before I drop $200 on something that wont work.

The car is a '74 dart hardtop with a /6, 904 and a 7-1/4 rear. I'm planning on a mildly built 318, 904, and a 8-1/4 or 8-3/4 rear, with original 14" steel wheels, I'm not sure on the width yet. I'm hoping to use the driveshaft I have, but if I need a new one, I can buy that at the same time as the rear.

What are the differences between the parking brake cables, if any? Will the minor difference in the rear ends spring perch cause problems down the road? I'm going to be using 14" steel wheels shod with 215-70-14 tiger paws, Is this tire size fine? I haven't bought the tires yet.
 
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