66 B body 8 3/4 to 72 A body swap

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IowaValiant72

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I have found a 8 3/4 locally that came out of a 66 belvedere.

Curious how well this will work in replacing the original 7.25 in my 72 Valiant. Im going from a slant 6 to a 318/904 combo and want something stronger out back.
 
I used a 1963 b-body in my 71 demon and it was a direct bolt in ...all I had to do was slot the perches.....only .5 of inch difference on each side compared to abody one...only drawback was tapered axles...Cass @ Dr. Diff....can fix that
 
Mtrhead said:
I used a 1963 b-body in my 71 demon and it was a direct bolt in ...all I had to do was slot the perches.....only .5 of inch difference on each side compared to abody one...only drawback was tapered axles...Cass @ Dr. Diff....can fix that
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Thanks for the info! I think i saw somewhere that only the early 8 3/4 have the taper but unsure
 
Probably true because the one I have is only ones I've seen....61-63 b - body...it's only an inch longer than an abody one....
 
So I have the exact same plan for use in a 72 duster. I used a 66 model year 8 3/4 to get the big bolt pattern.
Your only concern is that the valiant doesn’t have the wheel space a duster does.
The extra inch of axle width (at the axle flange) can be corrected with wheels.

Are you making any brake changes?
 
So here’s mine. I moved the spring perches in 1/2 by cutting the old ones off and welding new ones on. This makes it an easy fit.

4678F25E-FAF0-46E7-BE30-2A4CEBC73A5A.jpeg
 
AbodyBB said:
So I have the exact same plan for use in a 72 duster. I used a 66 model year 8 3/4 to get the big bolt pattern.
Your only concern is that the valiant doesn’t have the wheel space a duster does.
The extra inch of axle width (at the axle flange) can be corrected with wheels.

Are you making any brake changes?
Click to expand...
Eventually plan on going 4 wheel disc but probably only front disc for time being.
 
But like he said a valiant is not an open wheel well car like a duster and the maximum rim for that stock car is 7" wide until scraping
 
thanks mtrhead.

As for brakes I’ve danced this a while and want to finally prove this but I believe if you use the 10 x 1 3/4 drum from a six cylinder b body and the a body backing plate then you have the a body sized rear brakes with big bolt pattern.

Most go right to the 10 x 2 1/2 drum because they are still easy to find. I prefer to stay with the smaller drum because even that was too much brake for the big block cars. (Find the car reviews from when they were new) Even with the 10 x 1 3/4 brake as original the rear would lock up early.

What I’m really getting at is that with how we use our cars we will never need any more rear brake than what was original.
 
AbodyBB said:
thanks mtrhead.

As for brakes I’ve danced this a while and want to finally prove this but I believe if you use the 10 x 1 3/4 drum from a six cylinder b body and the a body backing plate then you have the a body sized rear brakes with big bolt pattern.

Most go right to the 10 x 2 1/2 drum because they are still easy to find. I prefer to stay with the smaller drum because even that was too much brake for the big block cars. (Find the car reviews from when they were new) Even with the 10 x 1 3/4 brake as original the rear would lock up early.

What I’m really getting at is that with how we use our cars we will never need any more rear brake than what was original.
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ive also seen evidence of this with other vehicles of the era. the plan is a unique street cruiser with intentions of a few passes a year on the track for fun. Having multiple little ones and the misses wanting to be able to take it out whenever is main factor in changing fronts to disc. Back in the day we would run old farm rigs with no rear brakes once the lines finally went
 
I absolutely recommend front disc brakes. When you brake the majority of the cars weight transfers onto the fronts. Given the brakes modern cars have we have to step up our game to stay safe.
As for track it’s been over 30 yrs since I’ve run anything. I can’t say anything there. ( I ran all 6 stuff because there was almost a half mile to stop)
And I can appreciate wanting to load the family up for an early evening cruise and ice cream
 
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