A-body 8 3/4 with big bolt pattern axles?

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DemonDave

DemonDave

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I picked up an A-body 8 3/4 housing and axles tonight for $200 and was surprised to discover that the axles were big bolt pattern. Can I assume this is a 1973 diff then? I think that was the final year for the A 8 3/4 and the first year for the big bolt pattern... I think.

It's missing the backing plates (and all the drum brake ***'y) as well as the brake lines and the 't' that bolts to the housing. Are these parts exclusive to this axle or fairly common?

Thanks!
 
DemonDave said:
I picked up an A-body 8 3/4 housing and axles tonight for $200 and was surprised to discover that the axles were big bolt pattern. Can I assume this is a 1973 diff then? I think that was the final year for the A 8 3/4 and the first year for the big bolt pattern... I think.

It's missing the backing plates (and all the drum brake ***'y) as well as the brake lines and the 't' that bolts to the housing. Are these parts exclusive to this axle or fairly common?

Thanks!
Click to expand...

I'm sure those are cut and resplined or aftermarket. Mopar never made a 8 3/4 LBP for the A-body.
 
Do those axels fit? As said before, no big bolt A-body 8-3/4. You can get backing plates off of almost anything except a 7-1/4". I got some 11" off a van with a 9-1/4". Those rears have c-clip, but someone pulled the gears out of it already, so less work for me. I got the pair with shoes, springs, cylinders, for $7 at the local u-pull-it. The drums are different, so I left those. The center register was larger. C-body 11" 8-3/4 drums are under $30 from Rockauto.com for Raybestos.
 
SGBARRACUDA said:
I'm sure those are cut and resplined or aftermarket. Mopar never made a 8 3/4 LBP for the A-body.
Click to expand...

That's very possible. Regardless, I'm happy that I don't have to have them redrilled for 4.5"!

Too bad I can't use the 7 1/4 backing plates since I happen to have a set in my car that I soon won't be needing... ;)
 
This got me worried.
I was planning to swap over some 7 ¼ brakes.
So I had to go out today and see if they would fit the 8 ¾.
I don’t see a problem.
They fit. Am I missing something?
And on a related issue:
I know that Erinburg talks about the rears being bad about locking up.
He recommend the smaller size diameter brake cylinders to have less pressure on the rear brakes.
I have experienced the rear locking up with the larger 11 inch (?) brakes that I am running on another Sport that I put together an 8 ¾ for.
So I am figuring these smaller diameter brakes will accomplish the same thiing as smaller diameter pistons.
Same principle: less braking force.

IMG_0495 (Small).jpg
 
The saga continues:

Had a knowledgable friend come over and it turns out the housing I picked up is from an E-body, not an A-body as I'd been told by the seller. I'm not overly worried though... my Demon's fat rear quarters can take the extra width... it's only a matter of 2 inches or so per side. The 15x7 rims I have now are at least 3-4" inside the wheelwell now, and that's with a 3/4" adapter (5x4 to 5x4.5) bolted on! I figure just moving the spring perches in to where they need to be is my only concern... and that's easy enough to do.

I like the idea of reusing the 7 1/4" brakes... that'd be a real money saver since mine are perfectly serviceable.
 
Something doesn't quite sound right. Thinking back to other cars I have seen with the E-body or wide B-body 8.75s, the wheels stuck out of the fenders and only a very offset wheel would correct it.

I ran a early B-body 8.75 (from a 68 charger - this is narrower than a E-body, but wider than an a-body) in my circle track duster. 8" rims with 4" BS. Because it was a circle track car all the fender lips were removed. If they weren't removed the tires would have rubbed.

If I were you, I would do some more measuring. What is the flange to flange distance and the spring perch center to center distance on the E-body rear. I have a chart from the MP chassis manual that gives dimensions of rear ends.
 
I have an E body 8 3/4 rear in my Duster. Yeah, the rear is
wider, but with the right wheels it fits. I have 15x8 wheels
with a 4 1/2 back space. I could even go to a 5in b.s. Heres
a pic on how well it fits.

000_0094_0001.JPG
 
Yea, I’m thinking your going to have make adjustments.
That E body rear is way wider.
I’m running a Diplomat 8 ¼ with cop rims and 215/70R15 in a Sport
Seems like it is around 54 + something flange to flange or about 1 ½ inches wider than the A. Would have to check that.
It looks way better than the skinny A rear anyway.
Those wheel housing stick way out on a Duster.
The only thing is that when I loaded the car up with people or stuff and hit bumps the tires would scrape.
I fixed that by building some heaver springs
 
I measured flange to flange and it's 55 1/2", spring perches are 46" center to center. I've begun considering having the housing narrowed to A-body specs and buying a set of custom axles from Strange or Moser to put in. I think that'd be the smartest plan for the longterm.

I'm in no hurry anyway since I'm still mulling over my engine options and winter is almost here...
 
Demon Dave you can use 7 1/4 backing plates and drums as long as they are the large bolt pattern and 10" like on a V8 car. I just parted out a '73 Dart with a 7 1/4 and checked the backing plates and drums against the backing plates and drums off of a pickup with an 8 3/4 and they are the same.


Chuck
 
Good to know, too bad my car's a SBP A-body! Still means that parts should be very common in junkyards. :)
 
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