Duster with b body 8 3/4 wheel set up

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DusterJoe89

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I recently got wheels for my 73 Duster which has an earlier b body 8 3/4. I am aware these axles are a semi popular option due to a body axle prices. I spent quite a while figuring out what wheels and what back spacing to use to accommodate a decent size tire. I figured I’d share what I ended up with to help other with the same set up

Rear-American racing 17x9 with approximately 5.8 inch back spacing and 275/40r17 tires

It is a bit tight to the wheel well, however around 3 1/2 inches from the leaf springs. If I did it again I would probably get an 8 inch wide wheel however it works pretty well. I also liked the fact that the wheels were only $180 a wheel at the time on summit racings website!

Anyway hope this helps others as I know the extra width of these axles can be an issue with finding wheels.

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Wow. That's a lot of backspace, to still have 3" to the springs. TTM's? (Mustang wheels?)
Do you know what year b-body axle? (65-67 are narrower than a 68-70).
 
3-1/2" to the leaf springs?

So it sounds like you have the springs relocated to the frame rails, but without a mini-tub?

B-body 8 3/4 axles work well in the Duster/Demon/Dart Sport bodies and even the Barracuda's, because they have more room to the quarter. You just have to run the appropriate backspace. Figuring out the backspace isn't all that difficult, you can just go to the rear axle width sticky An accurate 8 3/4" rear axle width list , take the width of your B-body 8 3/4 and subtract the width of an A-body 8 3/4 with BBP axles, and divide by two. Then take that number and add it to a know combination that fits an A-body 8 3/4 with BBP axles. Say, a 15x8 with 4.5" of backspace and 275's (which is pretty common combo for a Duster). Doing the math for an 8" wide rim and that combo gives you a backspace of ~5.65". For a 9" wide rim it should be more like 6.1" with that particular combo. Not something you're going to find really in a 15" rim, but easy enough for a 17" one or bigger.

I have a 68-70 B-body 8 3/4 in my Duster with a 1/2" spring offset and was able to run 295's with a little bit of quarter lip trimming with 18x10's and a 7" backspace (+38 offset).

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33IMP said:
Wow. That's a lot of backspace, to still have 3" to the springs. TTM's? (Mustang wheels?)
Do you know what year b-body axle? (65-67 are narrower than a 68-70).
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Has to be a 3" relocation, only way to have that much space and have the wheels inside the quarters with those specs
 
It is a 68 B body axle I got for free haha! It has spring re location kit. They are American racing wheels, I forget to part number off the top of my head but can get them. I thought about 18’s but wanted to stick with 17’s and am overall happy with the results.
 
DusterJoe89 said:
It is a 68 B body axle I got for free haha! It has spring re location kit. They are American racing wheels, I forget to part number off the top of my head but can get them. I thought about 18’s but wanted to stick with 17’s and am overall happy with the results.
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What springs?

You're going to be really close to rubbing the inside of the quarter or the bump in the stock wheelhouse with any kind of suspension travel
 
I rolled the fenders “gently” of course after the pictures haha. I do have to be careful in the wheelhouse on up travel however I run adjustable qa1 shocks and have not had any really issues in that department
 
Figure I’ll add to it. 68-70 B body rear, stock spring location and wheel tub. 15x8 5” backspace and a 255/60/15. Plenty of room all around.

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Turbo440Dart said:
Appreciate it. I have some custom cragars in those dimensions destined for the duster so I had to try them out.
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That will look great. I tried some standard 15 inch Cragars with standard 4x1/4 back spacing but they stuck out too much for my liking. It’s hard to beat Cragars on a duster, are you keeping the paint as it is?
 
DusterJoe89 said:
That will look great. I tried some standard 15 inch Cragars with standard 4x1/4 back spacing but they stuck out too much for my liking. It’s hard to beat Cragars on a duster, are you keeping the paint as it is?
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For now it’ll stay that way. Might eventually knock most of it down to the original blue.
 
Also did 65-67 b body with disc brakes. Rotor hat to hat is 60’’. Stock leaf location.
Went inexpensive route American Racing TT2 17x8 5.5 bs 255/45/17
1/2 from tire to lip and 1 1/2 from tire to spring.
Fronts 73 + disc brake same rims 5 1/2 bs caliper to the rear Hellwig sway bar and 235/45/17 good clearance. Could have gone a little wider in rear but keep it safe. With out spending a ton on custom bs rims, I’m pretty content. Tires and rims with lugs less that $1400

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Tony Barracuda said:
Also did 65-67 b body with disc brakes. Rotor hat to hat is 60’’. Stock leaf location.
Went inexpensive route American Racing TT2 17x8 5.5 bs 255/45/17
1/2 from tire to lip and 1 1/2 from tire to spring.
Fronts 73 + disc brake same rims 5 1/2 bs caliper to the rear Hellwig sway bar and 235/45/17 good clearance. Could have gone a little wider in rear but keep it safe. With out spending a ton on custom bs rims, I’m pretty content. Tires and rims with lugs less that $1400

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That looks good! Just out of curiosity did the disk brake conversion make any difference in width? I know it doesn’t usually but was just curious.
 
I don’t know. Didn’t measure before hand. I was told it makes it a little wider. Rear hat to hat is 60’’ Front is 58 3/4 now. My b body rear was 54 1/4 flange to flange. Wish I would’ve gone 1’’ taller in the rear, like a 255/50/17 but a lot more options with the 255/45/17s.
 
I have about 1 1/2 - 1 3/4 from top of tire to top of wheel opening. Rears around 27’’ Fronts around 26 1/2’’ from opening to floor.
 
DusterJoe89 said:
That looks good! Just out of curiosity did the disk brake conversion make any difference in width? I know it doesn’t usually but was just curious.
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All of the rear disk conversions add width, the rotor hats are thicker than the drums at the wheel studs. Typically they add about 3/16” per side.

Which fits those measurements pretty well, because a 65-67 B-body 8 3/4 is typically 59.5” wide, wms-wms, with drums. So a ~60” width after adding disks is about right.
 
Actually there is 1 thing. When adjusting torsion bars do they have to be the same amount of turns? At the same # of turns RF LCA bumper is closer to frame than LF side by 1/8 to 3/16. Any thoughts?
 
Tony Barracuda said:
Actually there is 1 thing. When adjusting torsion bars do they have to be the same amount of turns? At the same # of turns RF LCA bumper is closer to frame than LF side by 1/8 to 3/16. Any thoughts?
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The adjusters should be close at the same number of turns but they won’t be identical. The weight distribution isn’t perfectly equal left to right, and even the suspension points themselves have fairly significant tolerances.

Plus all kinds of stuff goes into that, even if one of the rear springs has a smidge more or less arch than the other it’ll throw the front out.

I set the height where I want it and don’t worry too much about the number of turns on the adjusters as long as it’s fairly close.
 
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