7 1/4" rear end

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MrJLR

MrJLR

Built, not bought
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Can my 7 1/4" rear end be modified for the 4.5" bolt circle?
Also, is it even worth bothering with it - can it be built up to handle around 450 HP?


:cheers:
 
spool it. for the "build and drill" price, you can get a bolt in strong 8.25 SG.
 
MrJLR said:
Where should I look? I just google it and I find the differential - I need the whole unit.
Click to expand...

The classified section on the forum has a few for sale usually or craigslist. They are expensive though and I bet a 8 1/4 could handle 450 for much cheaper.
 
if you can afford to buy or build a 450 horsepower Mopar and the transmission that can hold up, it will be a drop in the bucket as far as the cost of a rear end 8 3/4 or other..... 450hp mopar 5-7k. Built transmission 2-3k. 8 3/4 1-1.5k. 10k easy. Or Coble together old junk for 5k.
 
MrJLR said:
Where should I look? I just google it and I find the differential - I need the whole unit.
Click to expand...

Just go down the 15 to Ontario. The pic a part there has a few right now in there lot. MT
 
In order to confuse you more, I had a Dart Sport 340 car when I was a kid. The motor was strong but it was built by a guy (me) who was an expert parts-changer but knew nothing about setting things up. No way it was anywhere near 450hp, and I clearly remember exploding the original stock 8.25 with it. Never had a problem with the 8.75 that I replaced it with.
In my days as a Chrysler parts man in the 80's, I also clearly remember selling guts for 7.25's practically every day, even for Grandma's 225 Swinger.
 
last week, near the front where they keep the 'OLD" stuff three 70 to 80 a bodys. Mostly all there. A valiant four door V8, 60 something dart, slanty, to stripped to tell what year, at least for me, And a 360 powered four door with rear end still in it
 
MrJLR said:
Turns out I have an 8 3/4" rear end.....I was shown an identification chart and I lucked out....BIG relief!
Now it just needs a rebuild!
Click to expand...

OH BROTHER!!! #-o. now we know when the Lord was handing out brains we know who was holding the door for everyone else!
 
I must say, im very impressed with the way you modified that 7 1/4

just be sure its bolted in right
 
MrJLR said:
Can my 7 1/4" rear end be modified for the 4.5" bolt circle?
Also, is it even worth bothering with it - can it be built up to handle around 450 HP?


:cheers:
Click to expand...

No. I looked into doing it with my Dart and found that the axle shafts are thicker and a little longer. IIRC, 73 > had BBP on disk brake models. This carried with it, 10" drums on the rear. The hottest Mopar I've seen a 7¼" rear hooked to was a '66 Dart GT, with a 273-4 & a 904 transmission. IIRC, the 273-4/833 combo had an 8.75".

IIRC, The existing axle shafts & drums can be drilled for the 4½" BP. This is the sort of work for a pro and not for someone in their backyard with a Makita drill. If not dead on, vibrations rolling down the road or under braking will be plentiful.

IMO, 450 hp through a 7¼" would turn the interior of the housing into a greasy mess of something like chopped spinach. If the failure is really catastrophic, you won't win any friends at the drag strip by oiling down the starting line, either. [ame="https://www.youtube.com/watch?v=k6CnpWOGMFg"]https://www.youtube.com/watch?v=k6CnpWOGMFg[/ame]

Someone would be miles ahead to avoid the frustration expense of beefing up a 7¼ and go to an 8¼. Avoid any with less than a 2.76:1 ratio. They have been known to live well behind 450 HP and there is a lot more aftermarket support for it as well.

After re-reading the thread and finding out you have an 8.75 rear end. Ignore the above. I didn't edit it out because in a few weeks someone else will have a very similar question. It will be a reference for them.
 
MrJLR said:
Can my 7 1/4" rear end be modified for the 4.5" bolt circle?
Also, is it even worth bothering with it - can it be built up to handle around 450 HP?


:cheers:
Click to expand...

t would probably looks something like this

[ame="https://www.youtube.com/watch?v=099douUPsOE"]What do we need? ... MORE POWER! - YouTube[/ame]


(really, that's a repost?)
 

j par said:
OH BROTHER!!! #-o. now we know when the Lord was handing out brains we know who was holding the door for everyone else!
Click to expand...

That's the exact same way I laugh at you when you need your computer fixed.#-o

I'm brand new to this.
 
MrJLR said:
That's the exact same way I laugh at you when you need your computer fixed.#-o

I'm brand new to this.
Click to expand...

I once thought I had a 7 1/4 and it turns out I had an 8 1/4. I just always assumed since the car had a slant then it'd have the weakest rear end. Sometimes it's good to be wrong. You end up learning something and plus.. finding out you're wrong and have a beefy 8 3/4 rear is waaaay better than being right and having a 7 1/4" grenade.

As for the computer, some of us know a thing or two. I'm getting ready to build a new gaming PC.. full ATX tower, AMD octa core processor (which I'll overclock), liquid cooled CPU, 1 TB HDD, 500 GB SSD, and a Nividia 970 GTX graphics card, 16 GB DDR3 RAM (4GBx4), plus some other goodies.

Congrats on your sweeeet 8 3/4. Have fun :burnout: :burnout:
 
BlueDream said:
I once thought I had a 7 1/4 and it turns out I had an 8 1/4. I just always assumed since the car had a slant then it'd have the weakest rear end. Sometimes it's good to be wrong. You end up learning something and plus.. finding out you're wrong and have a beefy 8 3/4 rear is waaaay better than being right and having a 7 1/4" grenade.

As for the computer, some of us know a thing or two. I'm getting ready to build a new gaming PC.. full ATX tower, AMD octa core processor (which I'll overclock), liquid cooled CPU, 1 TB HDD, 500 GB SSD, and a Nividia 970 GTX graphics card, 16 GB DDR3 RAM (4GBx4), plus some other goodies.

Congrats on your sweeeet 8 3/4. Have fun :burnout: :burnout:
Click to expand...


LOL....thanks!

Computer sounds like a screamer.....I always go Intel but that's a great AMD!


:burnout:
 
MrJLR said:
That's the exact same way I laugh at you when you need your computer fixed.#-o

I'm brand new to this.
Click to expand...
You got me there ! Kinda ? I don't have a computer except for this cell phone and i use voice command at that--LOL! I'll give you credit for finding out before you bought another one.
Here is how I found out what rearend my first duster had- i put a big cam in, headers, edelbrock intake, holley four barrel, and a B&M shift kit. Next thing ya know i'm at the wrecking yard with my rear explaining the god awful noises. And that's the way I learned about a 7 1/4 ! The hard way "as always" !
Your thinking is correct (as far as drive train go's) - start at the back and work your way forward to the 450hp....
 
j par said:
You got me there ! Kinda ? I don't have a computer except for this cell phone and i use voice command at that--LOL! I'll give you credit for finding out before you bought another one.
Here is how I found out what rearend my first duster had- i put a big cam in, headers, edelbrock intake, holley four barrel, and a B&M shift kit. Next thing ya know i'm at the wrecking yard with my rear explaining the god awful noises. And that's the way I learned about a 7 1/4 ! The hard way "as always" !
Your thinking is correct (as far as drive train go's) - start at the back and work your way forward to the 450hp....
Click to expand...

I was lead astray...!
I was "told" it was a 7 1/4" ..."because it was originally a /6"
I didn't know how to identify it until I found that chart.....
It's all good!

I'm just glad I don't have to source a 8 3/4" :burnout:
 
MrJLR said:
Where should I look? I just google it and I find the differential - I need the whole unit.
Click to expand...

ill let you know if i ever see one. there was a 440 FURY in the junk yard in ANAHEIM no to long ago. i think this rear end was on it.

ooh, nevermind. lol damn confused the ifrst page for the last page again/
 
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