Rear end upgrade??

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BlueDream

BlueDream

Aspiring Mopar enthusiast
Joined
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Hey guys I've been looking around for a rear end to replace the 7 1/4 that i've got in the Dart. It was fine behind the slant but I don't think it will last very long behind the 318 that I'm dropping in. An 8 3/4 is just too expensive for me and I can't find an 8 1/4 around here. Are there any good alternatives? I saw the 8.8 swap but I don't think I need a rear that big for just a 318 and it also looks like a lot of work. Would something from a Dakota fit? I just need something with a low enough gear to be fun on the street and strong enough to take some abuse from the 'teen. Thanks
 
I'm sorry. Is that a Dart Sport?
If so check a Diplomat 8 1/4. You have to move the spring perches but it fits good. A fellow just listed one for sale, but it's in Illinois.
If it's a Dart, never mind. I think it would be too wide.
 
7 1/4 will be fine, run it. If you can find a Sure-grip center, even better, but don't loose any sleep over it, plenty of folks who run one with a teen. Driving style helps too, if your not neutral dropping and being an a**hole, it will last just fine.
 
Finding good rear ends is becoming an increasingly problematic situation for Mopar guys as well as in life in general. They're all either too wide in the beam, or just too expensive.

Many 318 cars came from the factory with 7.25s, so it might not be that bad unless you are planning on racing the car or really thrashing it on the street.

After looking at the options of narrowing and rebuilding an 8.75 or a 9" Ford (yuk) for my BB A body, I found that a super strong Strange S60 in the box was more economical. Just my 2 cents.
 
It is indeed a Dart Sport. If the 7 1/4 would live through burnouts and WOT on a regular basis then I'd change out the ring and pinion and try to find a sure grip for it, but I really don't think it'd live for more than a few months. It's not an automatic so I know I'm not going to be able to drive it gently all the time... or at all..
 
I read in the forums on here that a 8" from a furd ranger 4.0 would work. About stock A body length. Worth a look. Or, you could get a 87-96 Dakota rear, get it narrowed and just buy new axles or get a stock set cut and resplined The spring perches are 43" center to center from what I understand. Just a thought.
 
Some of the chuckle-head brand loyalists turn their nose up at the 'F' Word, missing the bigger picture. If your gonna chop and cut anything, a 8.8 is in a league on its own. Its price-point, strength, and the fact you get disk brakes is enough to say screw everything else.


The way I see it, if someone want's me to put the more expensive, harder to find, less optioned part on my ride, then hunt it down and pay the difference; nobody takes me up on it, and they always walk away.

Shock breaks axles, be it launching with a sticky tire, or dropping it in gear; smoothly applied power doesn't.
 
Is it possible that I could have an 8 1/4? I've read that you could get the 8 1/4 with a slant in 73 and when my grandpa bought the thing new, he knew he would be using it to tow stuff like boats and kids.
IMG_3325_zps98c5ed3d.jpg
[/URL][/IMG] I know it's not the best picture but it's the only one i've got where you can see the rear end. From what I've seen the 7 1/4 looks more angular and mine looks more rounded. I'm confused :wack:
 
Can't see it real good in the picture but it does look like an 8-1/4. Compare the cover shape to the pics in the chart Poison posted and you'll be able to figure it out.

BTW: the pic of the 8-1/4 cover in the chart shows the cover to be more oblong than round. I have also seen them with a more rounded cover, which is what yours looks like if I'm not mistaken
 
Another way to tell the difference is to measure the diameter of the axle tubes. 7-1/4 rears have 2-1/2" diameter tubes and 8-1/4 have 3" diameter tubes
 
Dude just count the bolts if you can't see the difference. In reality the 7 1/4 will work fine for a 318. Mine lasted five years behind a mild 360 and 3 sets of tires.
 
OldmanRick said:
This pic is a 8.25...

View attachment 1714717781

Someone changed it at some point.....That likely didn't come from behind the original /6. Strong enough, Yes. As far as gear ratio, likely in the low to mid 2's unless it was pulled from a 360 car? You may get lucky enough to have a 3.21?
Click to expand...

My grandfather is the original owner and he said the only big thing thats been changed was the engine. He broke the original 225 in the early 80's. He told me the 3 speed and rear end are original to the car so I always just thought it was a 7 1/4. Assuming he's not just old and forgetful and the rear end is actually original to the car, how many /6 darts came with anything other than a 7 1/4?
 
BlueDream said:
My grandfather is the original owner and he said the only big thing thats been changed was the engine. He broke the original 225 in the early 80's. He told me the 3 speed and rear end are original to the car so I always just thought it was a 7 1/4. Assuming he's not just old and forgetful and the rear end is actually original to the car, how many /6 darts came with anything other than a 7 1/4?
Click to expand...

forphorty said:
It probably has the 8.25 because of the standard transmission.
Click to expand...

I never actually eyeballed a 73' up slant with a stick. While surprised, I can see why they upgraded the rear with the 3spd. Thanks guys.....I'm never to old to learn. :thumleft:


P.S. I'm curious as to if it's a frt. disk car? Looks to be a big bolt pattern also?
 
My advice is quit the knitting circle, and slide your butt under there and get to counting bolts, and marking the tires and spinning them 1 full turn and watch how many times the drive shaft spins to get a good bead on what you have. Either way will work for your application.
 
OldmanRick said:
I never actually eyeballed a 73' up slant with a stick. While surprised, I can see why they upgraded the rear with the 3spd. Thanks guys.....I'm never to old to learn. :thumleft:

P.S. I'm curious as to if it's a frt. disk car? Looks to be a big bolt pattern also?
Click to expand...


Since drum brake 73' cars had small bolt patterns and 7.25" rears, does that mean the manual slant's required frt. disks if they indeed came with a 8.25? Just looking for knowledge...
 
PoisonDart74 said:
Some of the chuckle-head brand loyalists turn their nose up at the 'F' Word, missing the bigger picture. If your gonna chop and cut anything, a 8.8 is in a league on its own. Its price-point, strength, and the fact you get disk brakes is enough to say screw everything else.


The way I see it, if someone want's me to put the more expensive, harder to find, less optioned part on my ride, then hunt it down and pay the difference; nobody takes me up on it, and they always walk away.

Shock breaks axles, be it launching with a sticky tire, or dropping it in gear; smoothly applied power doesn't.
Click to expand...

I suppose that's why there are Mopar and Ford enthusiast sites. I'm a Mopar guy. I don't want a bunch of stinkin' Ford or Chebby parts on my ride. If you consider me ignorant for my opinion, go buy a camaro or mustang.
 
I had a 73 with a disk brake master cylinder, disk brake proportioning valve, and drum brakes. The car had 4-wheel drum brakes. Can't make the call whether it's a BBP car without checking the wheels. BTW - There are no 4-wheel drum brake A-bodies from the factory.

One of the problems you're going to find is that few of the 8¼ axles you'll find is going to have a gear ratio that will facilitate your desired use. Don't despair, after market support is out there for the 8¼. Just budget for the rebuild as you make your initial purchase.
 
Tube diameter is the easiest way to tell 7.25 from others. The 73 with LBP front disk brakes could very well have LBP 7.25 rear. I've got 2 of those laying here, one from a 73 V8 build and other from 75 \6 build. These are plentiful and cheap.
Reading you comments suggests to me that you will loose your drivers license long before you go through two 7.25 rears.
 
If it's 10 bolt, 8 1/4.

Something to keep in mind is a B body 8 3/4, I have one in my Dart Sport and it works perfectly. It's about 1 5/8" longer on each side. That would open up the door for a wider selection of gears.

8 1/4 will hold up fine for moderate applications.
 
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