Looking for advice on rear end width and wheel/ tire info for a Bo29 clone

[1cerberus4u]

Hey All, I posted this in another section of A-bodies, but now I think it may be better placed here....I'm not trying to create a new thread if one already exists (or point me to any other source for detailed info) but what I need to do, to turn my 68 barracuda into a Pro Street.

Is there a good thread or place to go, to better understand and see what specifically I need to do for....

So my questions are: Did the BO29's have tubs? if so, were they just to the frame or was the frame moved/knoched?
How wide was the rear end width wise? Stock or cut down?
What sized tires were the cars running?

Any thing else I need to do?

I already have a 400bb in it and an original Mr Fiberglass hemi hood

Looking for that BO29 factory Hemi look, with the rears tucked up under the rear, Something like this (if I can upload the pic)

I want my car (which is a 68 fast back that is in great shape) to look like this....

 

[abdywgn]

I think the springs were moved to the frame with offset hangers and the outer wheel houses might have been pounded upwards a bit? thought the original axles housings were unnarrowed B-body with 7" wide rims with a deep offset in toward the frame.

 

[Professor Fate]

You need to decide what you want out of the car and stick with it.
"Original BO29" and "Pro Street" as you show are nowhere near the same thing and represent two totally different outcomes.
THE original BO29:

BO29s as delivered:

Equipment (like the rear end) varied depending on whether the car was a manual or automatic, and some points could have varied during the construction run.
Manuals got Danas (IIRC narrowed to A body spec, also offered in the DC catalog), automatics got an 8.75.
No tubs, factory-type suspension using SuperStock springs, no relocation. Skinny steel wheels.
Most were modified almost immediately, or as class rules changed, or as cars migrated into new or different classes.
The Legendary 1968 Super Stock HEMI Barracuda ‘Mule’ to Lead Parade at Inaugural Sox & Martin HEMI Challenge - MoparInsiders

https://smclassiccars.com/plymouth/159913-1968-hemi-super-stock-factory-b029-best-of-the-best-arlen-vanke-original.html
NHRA BO29 information from 1968
Lots of info on L0/B0 cars in the forum dedicated to them...
If you want Prostreet, as in your picture; then build it how you want it. There are no set rules or specs for a Prostreeter.
If you want "original B0", go ahead.
But don't mix the terms together.

 

[1cerberus4u]

I think the springs were moved to the frame with offset hangers and the outer wheel houses might have been pounded upwards a bit? thought the original axles housings were unnarrowed B-body with 7" wide rims with a deep offset in toward the frame.

Wow, strange to think one could fit a tire that large in without a shorter axle or tubs... It would save me a ton of money if I could

 

[1cerberus4u]

You need to decide what you want out of the car and stick with it.
"Original BO29" and "Pro Street" as you show are nowhere near the same thing and represent two totally different outcomes.
THE original BO29:
View attachment 1716526486
BO29s as delivered:
View attachment 1716526497 View attachment 1716526518
Equipment (like the rear end) varied depending on whether the car was a manual or automatic, and some points could have varied during the construction run.
Manuals got Danas (IIRC narrowed to A body spec, also offered in the DC catalog), automatics got an 8.75.
No tubs, factory-type suspension using SuperStock springs, no relocation. Skinny steel wheels.
Most were modified almost immediately, or as class rules changed, or as cars migrated into new or different classes.
The Legendary 1968 Super Stock HEMI Barracuda ‘Mule’ to Lead Parade at Inaugural Sox & Martin HEMI Challenge - MoparInsiders

https://smclassiccars.com/plymouth/159913-1968-hemi-super-stock-factory-b029-best-of-the-best-arlen-vanke-original.html
NHRA BO29 information from 1968
Lots of info on L0/B0 cars in the forum dedicated to them...
If you want Prostreet, as in your picture; then build it how you want it. There are no set rules or specs for a Prostreeter.
If you want "original B0", go ahead.
But don't mix the terms together.

Yes, I want a "Pro Street" look as I am planning on a lot more cruising than track time and I like the way they look. I agree I am wanting to build it as I want, which is why I am looking at cars I like and asking what the combo is. Just trying to get info and compile what I am looking to do... Fun times!

 

[Professor Fate]

Yes, I want a "Pro Street" look as I am planning on a lot more cruising than track time and I like the way they look. I agree I am wanting to build it as I want, which is why I am looking at cars I like and asking what the combo is. Just trying to get info and compile what I am looking to do... Fun times!

Then quit worrying about the "original B029"s.
Concentrate on Prostreet or class cars- to fit that much tire you're going to have to back half the car.

 

[1cerberus4u]

Hey Professor... Guess that was one of the questions. Only way to get pro-street big tires in is to back half? Ok, well I build road race cars for fun so I do have tubing benders and migs etc so I can, but I was looking for something that I could get done easily/quickly (shorter axle and offset leafs) and be able to drive this summer, what with limited time to work on it. That said, any thoughts as to how tall/wide of a tire can fix (approx as all these cars are a bit different) with just shorter axle and inboard leaf kit?

 

[mopowers]

Like Professor Fate said, that car in the first photo likely has a full back half. No way that car has stock frame rails - at least not in the factory location.

Just doing a spring relocation and minitub, you should be able to fit a 325/50/15, 315/60/15, and 295/65/15 with a lot less work than a back half job.

 

[Professor Fate]

Hey Professor... Guess that was one of the questions. Only way to get pro-street big tires in is to back half? Ok, well I build road race cars for fun so I do have tubing benders and migs etc so I can, but I was looking for something that I could get done easily/quickly (shorter axle and offset leafs) and be able to drive this summer, what with limited time to work on it. That said, any thoughts as to how tall/wide of a tire can fix (approx as all these cars are a bit different) with just shorter axle and inboard leaf kit?

"Inboard leaf kit"? Which one? The 1/2-3/4 offset hangers? The framerail hangers?
Unless you plan to minitub it at a minimum (widen the tubs in to the existing frame rails) there is no reason to do anything other than the offset hangers, as your limiting factor will be the inside tub size (and the fender lip, of course).
With the 1/2" relocation, you should be able to tuck a 275 up into the stock wheel well with the proper backspacing on your wheel. No reason relocate the springs into the frame rail unless you do a minitub.
A minitub and relocating the springs to the framerail should allow use of (approx.) a 12" wheel with up to a 345/355 tire... maybe more, maybe less.
There is absolutely NO reason to have your rear end narrowed unless you back half the car, you just need the proper backspace on your wheel.
What is the proper wheel backspacing? You need to answer this yourself, as it will vary depending on which rear end you have (an A body 7.25, 8.25, 8.75 w/sbp and 8.75 w/lbp all have different measurements) as well as normal frame/body production variances, which can range pretty widely. A wheel measuring tool (or at least a tape measure and some basic math skills) are your friends.
To put it bluntly, you're not going to get anywhere near what you see in your mind's eye until you start cutting, big time. And when that time comes you'd better know what you're doing, or all you'll be doing is creating a pile of parts and taking another Barracuda out of circulation.

 

[mopowers]

One thing to keep in mind is that a shorter backspace makes it a LOT easier to remove and install the wheel/tire - especially with longer wheels studs. That means narrowing the axle is a good idea if you plan on running a big tire.

On my '66, with 315/60s or even the 325/50s, I had to have the rear at full droop and air down the tires in order to remove them. I've seen some folks even have to pull off one end of the rear shock and/or pull either the front hanger or rear shackle/hanger to remove the tires. That **** would really get old after a while.

 

[Professor Fate]

One thing to keep in mind is that a shorter backspace makes it a LOT easier to remove and install the wheel/tire - especially with longer wheels studs. That means narrowing the axle is a good idea if you plan on running a big tire.

On my '66, with 315/60s or even the 325/50s, I had to have the rear at full droop and air down the tires in order to remove them. I've seen some folks even have to pull off one end of the rear shock and/or pull either the front hanger or rear shackle/hanger to remove the tires. That **** would really get old after a while.

Excellent points. Especially if you're frequently switching between street tires and slicks. A second gen Barracuda (or Duster/Demon/Dart Sport) shouldn't be *quite* as much of an issue, but it's still a consideration.

 

[autoxcuda]

Originally delivered cars:

• ‘68 B-body width rear ends ( 4spd=Dana, Auto=8.75)
• Special offset rear rims to make up for the wider rear ends
• Offset front hanger, rear shackle (rear end perches put on to match)
• No wheel tub mods on the Barracuda’s
• Super stock springs

Special A-body width Dana came in the mid 70’s as a direct connection piece.

 

[autoxcuda]

Hey All, I posted this in another section of A-bodies, but now I think it may be better placed here....I'm not trying to create a new thread if one already exists (or point me to any other source for detailed info) but what I need to do, to turn my 68 barracuda into a Pro Street.

Is there a good thread or place to go, to better understand and see what specifically I need to do for....

So my questions are: Did the BO29's have tubs? if so, were they just to the frame or was the frame moved/knoched?
How wide was the rear end width wise? Stock or cut down?
What sized tires were the cars running?

Any thing else I need to do?

I already have a 400bb in it and an original Mr Fiberglass hemi hood

Looking for that BO29 factory Hemi look, with the rears tucked up under the rear, Something like this (if I can upload the pic)

I want my car (which is a 68 fast back that is in great shape) to look like this....

That car might be back halfed

But you can fit 315 maybe 325 width if you move the leaf springs in. I think USCT sells a kit.

If you straighten the sides of the tubs, they will give you more room. That will take some metal working.

This is a 70 Duster that has extremely similar tubs as a barracuda. Coincidentally being built/owned by the same guy, NS1RM21, who built/owned the primer 68 Barracuda pictured and video’d (by me) in previous post.

 

[1cerberus4u]

Like Professor Fate said, that car in the first photo likely has a full back half. No way that car has stock frame rails - at least not in the factory location.

Just doing a spring relocation and minitub, you should be able to fit a 325/50/15, 315/60/15, and 295/65/15 with a lot less work than a back half job.

Do I just went up to my shop and checked what I have now, which is BFG 275/60/15's and I have about 1/2 inch more to the leaf springs... and as one sees about 5/8" to the inner tub. I do not have offset brackets for the springs...

 

[1cerberus4u]

"Inboard leaf kit"? Which one? The 1/2-3/4 offset hangers? The framerail hangers?
Unless you plan to minitub it at a minimum (widen the tubs in to the existing frame rails) there is no reason to do anything other than the offset hangers, as your limiting factor will be the inside tub size (and the fender lip, of course).
With the 1/2" relocation, you should be able to tuck a 275 up into the stock wheel well with the proper backspacing on your wheel. No reason relocate the springs into the frame rail unless you do a minitub.
A minitub and relocating the springs to the framerail should allow use of (approx.) a 12" wheel with up to a 345/355 tire... maybe more, maybe less.
There is absolutely NO reason to have your rear end narrowed unless you back half the car, you just need the proper backspace on your wheel.
What is the proper wheel backspacing? You need to answer this yourself, as it will vary depending on which rear end you have (an A body 7.25, 8.25, 8.75 w/sbp and 8.75 w/lbp all have different measurements) as well as normal frame/body production variances, which can range pretty widely. A wheel measuring tool (or at least a tape measure and some basic math skills) are your friends.
To put it bluntly, you're not going to get anywhere near what you see in your mind's eye until you start cutting, big time. And when that time comes you'd better know what you're doing, or all you'll be doing is creating a pile of parts and taking another Barracuda out of circulation.

Wow, to all of you, thanks for the input. I appreciate it. So, great to hear no need to shorten rear end, that saves and I do have an 8 3/4, 741 rear end in it.

Yea, I'm thinking I don't want to back half it (although I have the skills to build 8-10 pt full roll cages that get certified for road racing, so I'm sure I can figure it out if needed.... I'm just trying to figure out easy and no so easy options to get there... thank you again!

 

[1cerberus4u]

One thing to keep in mind is that a shorter backspace makes it a LOT easier to remove and install the wheel/tire - especially with longer wheels studs. That means narrowing the axle is a good idea if you plan on running a big tire.

On my '66, with 315/60s or even the 325/50s, I had to have the rear at full droop and air down the tires in order to remove them. I've seen some folks even have to pull off one end of the rear shock and/or pull either the front hanger or rear shackle/hanger to remove the tires. That **** would really get old after a while.

Thanks Mopowers... Yea, I'm looking for easy on/off, although that said, I don't plan to put slicks on it. Just go to shows and get ice cream

 

[1cerberus4u]

Originally delivered cars:

• ‘68 B-body width rear ends ( 4spd=Dana, Auto=8.75)
• Special offset rear rims to make up for the wider rear ends
• Offset front hanger, rear shackle (rear end perches put on to match)
• No wheel tub mods on the Barracuda’s
• Super stock springs

Special A-body width Dana came in the mid 70’s as a direct connection piece.

Autox - is the B body rear end shorter? I thought no...

Though....... In other news I see your avatar and question, do you auto cross your A-body? I happen to also have a 67 coupe and have always wanted to make that a vintage "trans -am ish" road race car.... If you do, I'd love to connect on what you have done. = For full disclosure, I own several road race cars, including some newer and some vintage stuff, so that is more of my zone, although I love 60's muscle cars..

 

[1cerberus4u]

That car might be back halfed

But you can fit 315 maybe 325 width if you move the leaf springs in. I think USCT sells a kit.

If you straighten the sides of the tubs, they will give you more room. That will take some metal working.

This is a 70 Duster that has extremely similar tubs as a barracuda. Coincidentally being built/owned by the same guy, NS1RM21, who built/owned the primer 68 Barracuda pictured and video’d (by me) in previous post.

View attachment 1716526770

View attachment 1716526771

View attachment 1716526773

View attachment 1716526774

View attachment 1716526775

Great pics for mini tub extensions.. exactly what I was thinking. Being I do have a full time job, this would be a 2 ish week job for me, so I have to decide how deeply I want to jump in and then still have fun with the car this summer!

 

[autoxcuda]

Wow, to all of you, thanks for the input. I appreciate it. So, great to hear no need to shorten rear end, that saves and I do have an 8 3/4, 741 rear end in it.

Yea, I'm thinking I don't want to back half it (although I have the skills to build 8-10 pt full roll cages that get certified for road racing, so I'm sure I can figure it out if needed.... I'm just trying to figure out easy and no so easy options to get there... thank you again!

The 68 B-body rear is wider than A-body by 3”. So that’s 1.5” on each side.

To run a 68 B-body in an A-body, you need high backspacing rims especially with Mini Tubs. Most likely custom.


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"

 

[autoxcuda]

Great pics for mini tub extensions.. exactly what I was thinking. Being I do have a full time job, this would be a 2 ish week job for me, so I have to decide how deeply I want to jump in and then still have fun with the car this summer!

NS1RM21 took longer than 2 weekends and you can see the car was striped sandblasted and primered.

If you look closely there stuff done above a typical mini tub. That’s not a kit either. Hand made from flat sheet

There’s a flange he made between the trunk floor and inner tubs that he did on a stretcher. And some big lumps on the original inner was removed… on an English wheel.

 

[Air Grabbler]

My SS “clonish” Barracuda has 28x12” tires on 12” Keystone Klassic rims using a roughly 46” wide Dana 60 housing. The springs have been moved inboard. A larger tire/wheel will not fit the stock wheel wells.

 

[1cerberus4u]

My SS “clonish” Barracuda has 28x12” tires on 12” Keystone Klassic rims using a roughly 46” wide Dana 60 housing. The springs have been moved inboard. A larger tire/wheel will not fit the stock wheel wells.

View attachment 1716528317

Great looking car, congrats on the build! So, 46" wide housing, or 46" wide brake flange to brake flange?

And, what back spacing are you running on the 12"s in the rear?

And that that B/S level, the picture appears to show the wheel is outside the quarter panel? If so, by how much?

Again, such a cool car!

 

[Air Grabbler]

46” flange to flange. There is no choice in back space on the 12” Keystone Klassic wheels, so you can look it up. I don’t recall what it is.

The tires don’t stick outside the top of the wheelwell, but they do stick out down low where the bottoms of the quarter panels tuck inside.

The Hoosier slicks are a little tight on the front inside corner of the wheel wells. I have a half inch of clearance.

This combo works for me with the Cal-track and mono leaf springs, but you will have to mock up the specific wheels and tires that you are going to run on your car with your suspension.

The right way to do it is to tub the rear end. Or at least mini-tub it. The point of my response is that with careful measuring, you can just barely fit a 29x12 slick into a stock wheel well.

 

[dr dodge]

One thing to keep in mind is that a shorter backspace makes it a LOT easier to remove and install the wheel/tire - especially with longer wheels studs. That means narrowing the axle is a good idea if you plan on running a big tire.

On my '66, with 315/60s or even the 325/50s, I had to have the rear at full droop and air down the tires in order to remove them. I've seen some folks even have to pull off one end of the rear shock and/or pull either the front hanger or rear shackle/hanger to remove the tires. That **** would really get old after a while.

my old demon (tubbed) had the "backspace overhang" cragers on it
stock width 8 3/4 A housing
11" slicks. to take the tires off,
2 floor jacks up dangerously high and pull the rear lower shackle bolts and lower shock bolts

you are not wrong about it getting old fast
(we had to change between street tires and slicks at the track)

 

[1cerberus4u]

46” flange to flange. There is no choice in back space on the 12” Keystone Klassic wheels, so you can look it up. I don’t recall what it is.

The tires don’t stick outside the top of the wheelwell, but they do stick out down low where the bottoms of the quarter panels tuck inside.

The Hoosier slicks are a little tight on the front inside corner of the wheel wells. I have a half inch of clearance.

This combo works for me with the Cal-track and mono leaf springs, but you will have to mock up the specific wheels and tires that you are going to run on your car with your suspension.

The right way to do it is to tub the rear end. Or at least mini-tub it. The point of my response is that with careful measuring, you can just barely fit a 29x12 slick into a stock wheel well.

Really appreciate the insights and advice