DartThis74
Well-Known Member
I installed A b-body 8-3/4 rear in my '74 dart sport. If anyone is running American racing torque thrust II, what are you using as the offset to keep the wheel away from the wheel lip?
Anyone using American racing torq thrust on 8-3/4?
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Marcohotrod
Well-Known Member
how much wider is your b rear than the a was, b rears came in 2 different widths. and any brand wheel info about diameter, width, and backspaceing will help. what size tire are u thinking, with around an 8" wide wheel max? look at t thrusts with the most backspace
DartThis74
Well-Known Member
I first had a 7.25 rear original from factory under my 74 dart sport. The transplanted 8.75 b-body rear has been untouched, other than moving spring perches in 1/2 inch. I want to use the tires I have on my current wheels (15X8") which are cooper cobra GT's 235 width.
DartThis74
Well-Known Member
I'll get back with you on what the current offset is on the wheels I have
loganscuda
This/These
air shocks
Why would you do that? American Racing Torq Thrust II's are plentiful. Go on Summit and there are plenty of different offsets. I say, install the leaf and rear end into the car. Put some jack stands under the rear end and put some weight on the rear to simulate drive height. Measure/guesstimate where your mating surface of your brake to wheels are going to be and measure multiple times.
There are plenty of styles and designs to choose from...
http://www.summitracing.com/search/...4294909655&SortBy=Default&SortOrder=Ascending
Are a great way to destroy your shock mounts. They don't belong on anything. Do it right or don't bother.
Actually, B-body rears came in 6 different widths. Although, before '65 they had tapered axles, so it probably isn't one of those. That still leaves 4 different widths.
Rear end widths, drum-to-drum:
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"
A BODY
'66-'72= 57 1/8"
More than likely though it's either a 65-67 or a 68-70 B rear. If you've got a 68-70 B rear in there, I'd say with a 235 on a 15x8 you'd want a minimum of 5" of backspace, 5.25" would be better. You can go with more backspace than that too (probably up to about 6.25" of backspace), but the TTII's don't come with more than 5.25" of backspace in a 15x8. If it's a '65-67 than a 15x8 with a 5" backspace should be a piece of cake, and anything up to about 6" of backspace on a 15x8 would be fine.
I have a '68-70 B rear in my Duster. I run 18x10's with a 7" backspace and 295/35/18's, although I also added a 1/2" spring offset kit when I converted mine (perches at 42"c-c) and trimmed the outer quarter lip a little to squeeze the 295's into the stock wheelhouse.
69_340_GTS
Well-Known Member
Wheels with that much backspacing are going to be custom one-offs (usually). Many wheels cannot be custom ordered, and many styles can't even be made with those dimensions. Trying to find a 15x8 with 5 3/8" backspacing for mine right now, and cannot find anything. What wheel companies are you getting this type of wheel from? And then what do you put on the front that matches?
In 15 it might be hard but once you move up from there most modern rwd vehicles are designed with higher offset numbers and there are plenty of aftermarket wheels companies that make wheels for them.
My wheels are from a new edge mustang.
My wheels are from a new edge mustang.
69_340_GTS
Well-Known Member
Yeah, I can see Mustang wheels working on the back, if they want 17" or bigger wheels. But you can't run those large positive offset wheels on the front. So what goes on the front?
Mine are 17x9 33 offset rear, 17x8 0 offset up front. So 6"+ in the back, 4.5" front.
Wheels with that much offset are common in 17"+ diameters. In fact, wheels with that much offset are the norm with 17"+ wheels.
My rims are off the shelf, nothing custom about them. Enkei RPF1's. The rears are 18x10 with a +38 offset (7" backspace). I run 295/35/18 tires on them.
As for the front, once you go up to a 17" rim you can run as much as 5.7" of backspace on an 8" wide rim before you start to run into outer tie rod end clearance issues. I've seen a 17x9 with 6" of backspace on the front, but that would be specific to the design of the rim, most of the Mustang Bullit rims start to hit at 5.7".
If you go to 18" rims in the front, you can run even more. 18" rims can fit the outer tie rod inside the diameter of the rim, so, your only limit is the frame. My front rims are also Enkei RPF1's, 18x9" with a 35mm offset. That's a 6.4" backspace. Now, that isn't the whole story, I also have Dr. Diff 13" rotors which widen the track with 3/16", and I run a 3mm spacer. So, my effective offset is 27mm. But I also run a 275/35/18 up front. With a narrower tire you wouldn't need the spacer, and that amount of offset would be fine.
Honestly, the 65-67 B-rear is perfect for the Dusters/Demons/Dart Sports if you're going to run 17+ rims. It makes the backspace needed the same front and back, so you can rotate tires. The 68-70 B rear is a little wider, which is why my offsets are at 38mm in the back and 27mm in the front. The 65-67 B rear would even them up the offsets needed.
Dartnut
Don't hate me because i'm beautiful
I have a '69 B-Body rear in my Dart Sport with the perches moved in 1/2'' on each side.
I then rolled the inner wheel lips for clearance, (i didn't need much).
When i installed 002 and 003 Super Stock springs, i had even more clearance.
I am using 15 X 6 1/2'' with 3 1/2'' back space stock Rallye wheels with 255 60 15 tires. I have at least an inch of clearance to the inner wheel lip and could go about 2'' more toward the spring safely.
I'm sure i could fit 15 X 8'' wheels in there with a 275 60 15 with the right offset and no spring relocation or mini tubbing.
I then rolled the inner wheel lips for clearance, (i didn't need much).
When i installed 002 and 003 Super Stock springs, i had even more clearance.
I am using 15 X 6 1/2'' with 3 1/2'' back space stock Rallye wheels with 255 60 15 tires. I have at least an inch of clearance to the inner wheel lip and could go about 2'' more toward the spring safely.
I'm sure i could fit 15 X 8'' wheels in there with a 275 60 15 with the right offset and no spring relocation or mini tubbing.
Wheels with that much offset are common in 17"+ diameters. In fact, wheels with that much offset are the norm with 17"+ wheels.
My rims are off the shelf, nothing custom about them. Enkei RPF1's. The rears are 18x10 with a +38 offset (7" backspace). I run 295/35/18 tires on them.
As for the front, once you go up to a 17" rim you can run as much as 5.7" of backspace on an 8" wide rim before you start to run into outer tie rod end clearance issues. I've seen a 17x9 with 6" of backspace on the front, but that would be specific to the design of the rim, most of the Mustang Bullit rims start to hit at 5.7".
If you go to 18" rims in the front, you can run even more. 18" rims can fit the outer tie rod inside the diameter of the rim, so, your only limit is the frame. My front rims are also Enkei RPF1's, 18x9" with a 35mm offset. That's a 6.4" backspace. Now, that isn't the whole story, I also have Dr. Diff 13" rotors which widen the track with 3/16", and I run a 3mm spacer. So, my effective offset is 27mm. But I also run a 275/35/18 up front. With a narrower tire you wouldn't need the spacer, and that amount of offset would be fine.
Honestly, the 65-67 B-rear is perfect for the Dusters/Demons/Dart Sports if you're going to run 17+ rims. It makes the backspace needed the same front and back, so you can rotate tires. The 68-70 B rear is a little wider, which is why my offsets are at 38mm in the back and 27mm in the front. The 65-67 B rear would even them up the offsets needed.
Why isn't the rear tire centered in the opening?
I have AFCO springs in the car, which like the MP oval track springs and the SS springs move the axle back about a 1/2" to center the wheel in the wheel tub and maximize tire clearance, unless you use special hangers. It was done for the drag race and circle track cars so they could run larger diameter tires and still clear the wheel tubs. The stock location limits tire height and causes rubbing because it isn't centered in the tubs.
The factory axle position doesn't center the wheels in the openings anyway, which is hard to judge to begin with because the wheel openings are not symmetrical. "Centered" is a matter of where you measure from on the opening, since the openings don't have the same radius, angle, or even height in the front as they do in the back.
Regardless, my wheels are centered to the wheel tub and are probably just as close, or closer, to being centered in the openings than the factory location which is forward of center.
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