ir3333
Well-Known Member
For those using a B body 8 3/4 in a Duster, what wheel, backspace and tire combination did you use?
Would 15" x 6" or 6 1/2" be a good fit?
Would 15" x 6" or 6 1/2" be a good fit?
B body rear axle in an A body
- Thread starter ir3333
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txstang84
Well-Known Member
I'll be doing that one as well, but it depends on what year B body. The Duster has a little more room in the wells than a Dart or Val...you have room for 15x8 with the right backspacing on the wheels-- @nublu72 is probably who you need to talk to
B-Body 8 3/4 Rear End in an A-Body | For A Bodies Only Mopar Forum
7th post 72bluNblu.
I have the earlier B Body axle with 15" Rallyes (don't recall the width-sorry). I am running (wider than ideal) 275/60-15 tires on a 68 Dart, the narrower wheel does pull the width of the tire in a little. It did require some lip trim which I wish I didn't do way back then. During rebuild, I rolled the edges rather than cut them, but I will also be looking for a little narrower tire for these wheels and a set of 17's with more backspace for better grip. That way I can change the looks or purpose of the car at will.
7th post 72bluNblu.
I have the earlier B Body axle with 15" Rallyes (don't recall the width-sorry). I am running (wider than ideal) 275/60-15 tires on a 68 Dart, the narrower wheel does pull the width of the tire in a little. It did require some lip trim which I wish I didn't do way back then. During rebuild, I rolled the edges rather than cut them, but I will also be looking for a little narrower tire for these wheels and a set of 17's with more backspace for better grip. That way I can change the looks or purpose of the car at will.
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Dartnut
Don't hate me because i'm beautiful
I run a stock width '69 B-Body rear end with factory axles and 10'' drum brakes in my '74 Dart Sport.
All I had to do is move the spring perches in 1'' on each side.
The wheel and tire combo I use is a stock 15 X 6 1/2'' Mopar rally wheel with 255 60 - 15'' radial T/A tires.
Also, I use Super Stock 002/003 springs on it.
I rolled the inner wheel lips in but I didn't need to, It was done for safety's sake.
There is a good 1 1/2'' room between the tire and the spring as well.
I could easily run 275 width tires with the correct offset.
All I had to do is move the spring perches in 1'' on each side.
The wheel and tire combo I use is a stock 15 X 6 1/2'' Mopar rally wheel with 255 60 - 15'' radial T/A tires.
Also, I use Super Stock 002/003 springs on it.
I rolled the inner wheel lips in but I didn't need to, It was done for safety's sake.
There is a good 1 1/2'' room between the tire and the spring as well.
I could easily run 275 width tires with the correct offset.
Depends on what B body.
I had a 66 Coronet 8 3/4 under my 73 Duster and used factory 15x6.5 rallye wheels, whatever that backspacing is.
It did bring the rear wheels out even with the factory disk brake front wheels.
I had a 66 Coronet 8 3/4 under my 73 Duster and used factory 15x6.5 rallye wheels, whatever that backspacing is.
It did bring the rear wheels out even with the factory disk brake front wheels.
ir3333
Well-Known Member
How about a picture
ir3333
Well-Known Member
What backspace on the 6 1/2 Rallies...4.25?
Tx guys...any pictures?
Tx guys...any pictures?
My '72 Dart has a B-body housing, not sure of the leaf spring offset, for a wheel, hold your breath, Mustang bullet wheels. The rear backset is about 6". Not sure of the rim width, they are 17". Tires are 245/45/17's. The fronts are from a different year and have a little less backset, but have a spacer to get clearance for the rod end. I bought the car this way. If you would like more information, I will be out in the woodshed (garage) later.
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txstang84
Well-Known Member
if those are factory style 17x8 bullitt wheels, they're 5.78" backspace (30mm offset).
Pretty sure the rears are 6". The spokes are slightly different than the fronts, and have a different backset. Center caps are also different. I bought some aluminum Center caps from Hughes, they fit the fronts, had to machine the rears to fit.
Seems like everybody's nailed it so far. B-body 8 3/4 in a Duster is a pretty good swap, especially if you want to run larger diameter wheels (17/18) because they generally have the backspace you need right off the shelf. Stock perches on a B-body are 44" center to center, so you will need to move the perches to 43" for use in an A-body with the stock spring locations.
It does matter which B-body rear end you use, because there are different widths. You can see that here, and compare to the A-body width. The perch location also changed for the '71+ cars.
8 3/4" Rear end widths, drum-to-drum:
A-BODY
Before I did the disks and larger wheels I was running 15x7's with a 4.25" backspace, I had 225/60/15's on those but that was about all the room I had to the uncut quarter lips. If you wanted to run wider tires than that on the 68-70 B rear you'd need more backspace. A 15x6" seems really small, especially on a Duster. Those little guys will get lost in the wheel wells. Even the 15x7's with 225's looked tiny on my car.
Keep in mind that a Duster has an entire extra inch of room to work with to the quarter lip compared to a Dart. Springs and frame rails are in the same place, but the Dusters/Demons/Dart Sports have wider quarter panels and outer wheelhouses.
It does matter which B-body rear end you use, because there are different widths. You can see that here, and compare to the A-body width. The perch location also changed for the '71+ cars.
8 3/4" Rear end widths, drum-to-drum:
A-BODY
- '66-'72= 57 1/8” (or 57 13/16” for BBP axles and brakes)
- BBP 8.25/7.25= 56 3/4”
- '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"
Before I did the disks and larger wheels I was running 15x7's with a 4.25" backspace, I had 225/60/15's on those but that was about all the room I had to the uncut quarter lips. If you wanted to run wider tires than that on the 68-70 B rear you'd need more backspace. A 15x6" seems really small, especially on a Duster. Those little guys will get lost in the wheel wells. Even the 15x7's with 225's looked tiny on my car.
Keep in mind that a Duster has an entire extra inch of room to work with to the quarter lip compared to a Dart. Springs and frame rails are in the same place, but the Dusters/Demons/Dart Sports have wider quarter panels and outer wheelhouses.
txstang84
Well-Known Member
Center caps have to be different because the OE ones sit deeper in the hub register and can't accommodate the grease cap on the rotor when installed...pretty well documented swap. No factory bullitt wheel has a 6" backspace...factory (and factory mimic'd) 17x8s have 5.72" backspace (30mm offset) for 99-04, and 6.295" (44mm offset) for 05-09 year models. There are some 17x9s with a 5.94" backspace though...
goldduster318
Overzealous Car Modifier
The good news is if you have the large bolt brakes in the front, you could basically have "square" and rotatable tires.
My friend has my old wheels which were 15x7 4.125 backspacing and they have a mile of clearance on all stock everything but the axle in the rear on a 71 Demon.
I have 275-35-18's now but with offset shackles, but it would have cleared with the axle in the stock location I would think too. My car is extremely similar to 72bluNblu for the rear axle setup.
The B-body axle is the right choice for a Duster/Demon/Dart sport. Will look better with ANY set of wheels than the OE width.
My friend has my old wheels which were 15x7 4.125 backspacing and they have a mile of clearance on all stock everything but the axle in the rear on a 71 Demon.
I have 275-35-18's now but with offset shackles, but it would have cleared with the axle in the stock location I would think too. My car is extremely similar to 72bluNblu for the rear axle setup.
The B-body axle is the right choice for a Duster/Demon/Dart sport. Will look better with ANY set of wheels than the OE width.
OK, I was off, 5 15/16" rear. Fronts are 5 3/8" backset. Sorry, I don't measure like you do, that's bead to the hub. My perches are 42, 1/2" offset shackels.
Did not mean to bog down this thread with this.
Did not mean to bog down this thread with this.
txstang84
Well-Known Member
It's not bogging down anything lol-I agree with you!
Your experience is valuable to this thread because someone else may want to replicate your setup and measurements are relevant to the swap. 72bluNblu has provided his info on numerous other threads, but yours may be the path others would choose instead of 18" Enkeis like his Duster. As a matter of fact, this was the route I was planning as I have an 8 3/4 from a 66 B body with 1/2" offset shackles I bought from a seller on here, and will be running Cordoba rotors up front, so what you already have is what I've wanted to do-for that, I greatly appreciate that you've posted your setup and experience. I just can't get on mine yet because i have other projects in front of my Scamp.
Dartnut
Don't hate me because i'm beautiful
I'll do better than that.
If you click on the link at the bottom of my post, you can read my build thread that has lots of pictures etc. on the modifications and installation in my car.
(It's the little one in blue)
Tell me what you think after.
Exactly!
That was my original motivation for the ‘68-70 B rear. I got greedy with the rear tires and so I ended up with a staggered set up I can’t rotate. But my offsets are basically the same front and rear, +35 front and +38 rear.
But the math works, with a ‘68-70 B rear in a Duster/Demon/Dart Sport and a 1/2” spring offset (you have to move the perches anyway so why not) you basically run a +30 to +35 offset front and rear and can rotate the wheels if you run a square set up.
If you wanted to stick with 17’s that would get you up to 17x8’s with 255/45/17’s with like a 5.7” backspace (+30 offset). The reason for that is the outer tie rod interference, with most 17” rims 5.7” is about the backspace limit before the tie rod becomes an issue. That kinda rules out 275’s with 17’s unless you get into doing more body work.
With 18’s the outer tie rod fits inside the lip of the rim, so running square you could do 18x9’s or 18x9.5’s with a +30 or +35 with up to 275/35/18’s. That’s a 6.1” to 6.4” backspace, for 275’s the minimum backspace is about 6” unless you really roll the fenders.
Obviously that’s a guideline, that’s the offset you need with 73+ BBP disks. Changing the braking set up can change the track width. And the body tolerances on these cars vary, most should be able to run those recommendations without too much trimming or rolling of fender lips but it all depends on the particular car and it’s ride height.
If using a '65-67, you can run any factory wheel you wish.
The 65-67 B body rear only buys you an extra 5/8" on your backspacing compared to the '68-70.
While that would mean you could run a factory 15x7, 4.25" backspace wheel with a 255/60/15, that's the best it'll get you.
Unless, of course, you run the ride height so that your quarter lip is a few inches above your tire. At which point you can run anything you want under 28" tall, because it'll just stick out past the quarter lip and you should have enough clearance that the rubber never hits the body. But that's not actually fitting the wheel inside the wheel well.
I had the 15x7 rallye's, with 235/60r15's. Fit like a glove. However, the aluminum slots in the picture are some deep dished, and I did have to fold the inner lip up to keep them from rubbing. I've always like the 65-67 b bodies in Dusters. In fact, I just set one in my other Duster, still have brakes/driveshaft etc to do.
ir3333
Well-Known Member
That was a fantastic build thread ...congrats!
...the B body 8 3/4 you installed have the 15 x 7 rallies with 275 60R15?
Looks great!
Wvbuzzmaster
Well-Known Member
A good fit on my Duster with whatever unidentified B body rear axle it has was a 15x8 with 5.5" backspace. I am running 255/60R15 but I could probably get a 275 on it using the same rims.
@Dartnut @ir3333
I have a 68-70 B-body housing and 489 I would like to build for my Duster. Currently it has a 8.25".
I would like to run a 15x8 Rallye wheel. They only come in 4.5" backspace. I have the wheel lip trimmed and plan on getting Doctor Diffs 1/2" spring relocation. Wil that wheel work with a 68-70 B-body rear in a Duster?
189871948130848846
I have a 68-70 B-body housing and 489 I would like to build for my Duster. Currently it has a 8.25".
I would like to run a 15x8 Rallye wheel. They only come in 4.5" backspace. I have the wheel lip trimmed and plan on getting Doctor Diffs 1/2" spring relocation. Wil that wheel work with a 68-70 B-body rear in a Duster?
Dartnut
Don't hate me because i'm beautiful
Thank you for the compliment, it was a lot of work!
The car has factory 15 X 6 1/2 rally wheels off of a Cordoba and 255 60 15 radial t/a tires on the rear.
Dartnut
Don't hate me because i'm beautiful
I think it would work depending on how big of a tire you use and the springs used in the rear.
For example, on my car with the Super Stock springs, I could probably run that wheel with a 275 60 15 because the springs lift it up more on the back end and the factory wheel tubs don't come into play.
If your car is lowered for handling or even stock ride height, the tires might rub with that size of tire.
You'll have to mock it up and measure before you buy tires is my advice.
Good choice using the offset hanger kit from Dr. Diff.
He is a great guy and his knowledge, prices, and shipping are very good.
I have bought a fair amount of parts off him in the last several years.
If you decide to change the gears in the 489, get the crush sleeve eliminator kit from Dr. Diff.
I did and it worked out very well.
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