What rear axle to purchase and narrow

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tooslow

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I would like to narrow my rear axle but do not want to destroy my 8 3/4 .
The car is 69 Dart GT . What is a good axle swap . The car is around 500 hp and has a BB
thanks for your suggestions
 
best bang for the buck is the Ford Explorer rear axle -- 31 spline axles stock and lots of parts available -- easily takes 500 hp ,,,and details on narrowing are posted here on the site.,,,, next bet is a custom 9 inch Ford from Moser , Strange etc .
 
How much are you going to be narrowing the axle and what modifications have you done to the car that require a narrower axle? Have you done the 3 inch spring relocation location kit and installed mini tubs or widened the stock wheel wells?
 
15X12 inch 7 1/2 Back space wheels with 29 x 14.5 hoosiers with a factory width 8 3/4 rear and a lot more then 500 HP . Easy gear swap and its mopar. Over 10 years of abuse with big motors and no issues. Back brace it. Flex is the downfall of the 8 3/4. Flex the rear housing and the axles will stress the differential caps.

10 inch wide wheels with a 6 1/2 inch back space will fit right on a Dart with an inboard kit. I left my factory spring perched in place and just added two others incase I wanted to reuse it in another car.



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Steve 109.JPG
 
Ford 9" or Dana 60. You'll get arguments from the Mopar chest thumpers but either of those is arguably a good bit stronger than the 8 3/4, plus, you won't be sacrificing your 8 3/4. I would choose the Ford 9" simply because of it's brute strength and its immense aftermarket support. IMO it's stronger even than the Dana 60. Let the arguments ensue. lol
 
The Chrysler 9-1/4 is also a viable option. You’re into it for minimal expense to start with and the cost of axles from Cass (Dr. Diff) and narrowing.
 
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The Chrysler 9-1/4 is also a viable option. You’re into it for minimal expense to start with and the cost of axles from Cass (Dr. Diff) and narrowing.

I agree! That one seems to be overlooked a lot. Only "possible" drawback is, it's not supported "quite" as good as some of the other choices.
 
You are going to get opinions from ALL over the map and that is good . I suggest a 9" custom made with axel and brakes . Why? Comes to your door ready to install , your choise of ratios , your choise of width , AND , 31spline axels . Cost ? Unless you have a yard full of parts , in the long run , the cost is the same . JMO
 
If you decide to go with a Ford 9 inch you can get stock disc brakes if you look for a 70s 80s Versailles and loaded Granadas and Monarchs.
 
Agree with a lot of the above, a Dana just looks right under a Mopar, a nine can be unbelievably strong, a 9 1/4 has a good lsd available, and custom axles can be had for almost anything, but.....
if you can do some or all of your own work, an 8.8, basically a copy of the beloved-by-the-chevy-crowd 12 bolt, can be narrowed, with gears, disc brakes, and a posi (sorry) for about a quarter of the price of the others, depending on what you find under an explorer, or mustang.
I have a Dana under one car, a nine under two others (both narrowed with a spool) and a 8 3/4 with gears and a locker. If I were looking (and I am, for a 57 chevy) I would absolutely get an 8.8 .
If you can weld, there are videos on you tube that show you how to narrow a 8.8 at home.
 
If you use a 9-1/4 and stay with the small bolt pattern wheels, you can use your existing brake setup off of your 8-3/4. Depending on what you get into a 9-1/4 for, it has potential to be significantly less expensive than the other options.
 
Cost wise 8.8 explorer I bought a running/driving explorer 4:10 gears pulled diff sold the rest of truck for what I paid cost me 150$ for machine shop to shorten long side will be into the diff for 500$ bought 2 new short side axles and it has disc brakes !
 
We went with a truck Dana 60 from a bigger Ram or B van. Most will be 3.54 or 4.10’s and a 4.56 mixed in.

Toss all the brake and axle stuff, cut and jig weld the ends on and go from there.

Last two were $150.00 ea. Down side, no pinion snubber mount but then you give that up with an 8.8 and 9”

Cliff Ramsdell
 
If you decide to go with a Ford 9 inch you can get stock disc brakes if you look for a 70s 80s Versailles and loaded Granadas and Monarchs.
I would not go that route and I have two of them (Versailles). Parts are hard to get for the disk setup

The correct answer is FORD 9 INCH. 3rd member, so it's easy to swap gears (even for an old man) tons of support and parts available, and "looks enough like" an 8 3/4 that you just don't need to say anything if you don't want to LOLOL

Beware in your travels, that you don't get a Ford 8-ish inch used in some of the smaller cars (looks just like a 9) or the Lincoln type 9" "plus" which looks like a 9, uses a different ring gear, and has LARGER than 4 1/2" bolt pattern

Ford Axle History and Identification: Ford Differentials

Here's some stuff on the "bigger" oddball Lincoln axles

How to identify 9 3/8 LS or open axle from the outside? - Ford Truck Enthusiasts Forums

You CAN, I am told, install a 9" 3rd member into a "big Lincoln" 9 3/8 housing. IF you are having custom axles made, one of those housings "cheap" might be an option
 
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If you decide to go with a Ford 9 inch you can get stock disc brakes if you look for a 70s 80s Versailles and loaded Granadas and Monarchs.
I've got one from my 71 Duster. Seriously, you don't want to use the brakes from those.

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Somebody thought it was a good idea at some point, but after thrashing around trying to get a decent set of brakes of it I gave up and replaced it with an 8-3/4"
 
Quick Performance 9" or start with a housing/axle package from Speedway Motors. They have tons of widths for for around $799
 
Doesn't the caliper interfere slightly with narrowing the rearend farther? I know the 7.5 axles can be used in the 8.8 so that the small brakes and backing plates can be used; allowing farther narrowing.
 
I went with a Dana in my 70 Dart. Strange S60. Detroit Locker 3:73 gears. 35 spline chromoly axle shafts. The only reason I’d use a 9” is for the easy gear swaps.

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I say mopar 9 1/4. Local junk yard $350 out of a truck and will go through it to make sure it’s good. Told him I was going to narrow it for a dart and new gears with a sure grip and he said $250 as is.
 
There's so many companies building custom nines that it would be very difficult for me to make any other choice than that for high horsepower; and stick with an 8.8 for around 400 hp because they're vastly cheaper to initially purchase and the short axles are practically free.
 
I shortened an 8¾ housing from a B body myself (then save your A body housing)and ordered axles from Dr Diff for like $300 been hammering on it with 500+hp 440 with no issues so far
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