8 1/4 rearend question.....

[70-duster]

How reliable are these rearends? I have a 8 1/4 out of a 74 dart that has 36,000 original miles on it. I also have a b body 8 3/4 out of a 67 coronet. Neither of the rearends are posi and I'm not sure what gears they have in them. I am just trying to figure out what my best option is. The car will be a weekend cruiser and the engine will be slightly modified. I like the option of being able to just bolt in and go, but is that the best. I just don't know much about the 8 1/4's.

 

[superdart]

Some people are going to say to narrow the 8.75, but really, if you are planning a mild to moderate engine build the 8.25 will hold up just fine.

Once upon a time everyone thought the 8.25 was crap and the 8.75 was the only way to go. Now that 8.75s are drying up (or at least getting expensive) people have figured out that 8.25s can take the power, they just need a little love.

There is a good Mopar Action article about building up the 8.25. I have it in PDF format. PM me your email address and I will send it to you (I do not want post it here and piss off the copyright gods).

Your housing "should" have the larger carrier bearings. In '75 they went to a small diameter (inside diameter is the same). The carrier was a 27 spline unit, and there were two types: 2.45 gear set version, and everything else.

All carriers up to 1996 and older will be a drop in fit. In 1997 they changed to an improved 29 spline version that has bigger C-clips. These can be found in Dakotas and Durangos (non-5.9L vehicles).

The late model Dana Trak-loc that is factory in the late model is very affordable, even from the dealer (under $200). The catch is that you will need to order specific axles that are "A-body" but with 29 spline late model ends. It will also use the larger C-clips that are readily available from the dealer.

There is also the benefit that 94-98 Jeep Grand Cherokee rear disc brakes (11" rotors) are a near bolt-on mod for any 8.25 with a 5x4.5 bolt pattern.

Having said all that, I have just completed rebuilding my 8.25 from a stock 2.45 open unit to a 29-spline 3.55/Trak-Loc with custom axles, cover and the Jeep brakes. Thread is here:

http://www.forabodiesonly.com/mopar/showthread.php?t=153229

 

[oldkimmer]

............Ur B body 8.75 is only about an inch wider each side.........move the spring pads i 1/2 ea side........depending what ur putting it into u wont even need more offset on ur wheels.........the 8.25 will do just fine.......kim..........

 

[leblanc]

8.25's can handle in the ballpark of 350 HP with no issues
The 8.25 you have would be an easier swap than the 8.75
How much HP do you have? My 76 Dart Sport has about 325 and still has the 7.25 that came with it.
can't do burnouts with it though, it will go pop!!!

 

[yellowdartdave]

can't do burnouts with it though, it will go pop!!!

It is not the burnout that destroys them..it is when the tires finally hook that kills them.

...don't ask how I know of this fact. ops:

 

[cudamark]

Of your two choices here is the good and bad......

8 3/4
Good.....very strong and reliable. Easy to swap gears and sure grips as a unit.
Bad.......in your case, just the fact that it's a B-body one and needs to be modified to
fit an A-Body and wheel/tire clearence can be an issue in some cases.

8 1/4
Good......fairly strong center section. Relatively easy to find and parts are plentiful
Bad........Weak axle shaft design (C-clip type retainer and axle bearing runs on axle
shaft), changing gears requires a complete re-setup and in some cases, a new
carrier.

 

[pettybludart]

Do the B-body rear,find a good sure-grip center section with your choice of gears.There is 3 kinds of 8 3/4 centers with the last 3 numbers being 741,742 and .489.I prefer the 489 myself,more plentiful.If your just using as a daily driver,with no racing the 8 1/4 will work fine.

 

[rumblefish360]

The 8-1/4 is plenty tuff, very durable and will take over 400 HP/Torque with out issue.

You'll have people try and scare you about it being a C clip rear and it is infeior to the 8-3/4. Worry not. For a cruiser with power, you'll be fine.

 

[superdart]

Agree with Rumble....people are scared of the C-clips, but keep in mind that there are tens of millions of C-clip vehicles on the roads:

All non-8.75 Darts
All FMJ bodies
All Dakotas and Durangos ever built
All Rams (including the new ones)

All the Ford 8.8s out there (Mustangs and F-150s, anybody?)

Yeah, there is nothing wrong with C-clips for most applications.

 

[Brad4406]

I would put in the 8 3/4". I've ran pre 71 B-body 8 3/4 rears in a 75 Dart Sport and in 71 Duster. No modifying of the housing is required, other than cutting off the spring perches and welding them back on once you ensure the rear is centered and set to the proper pinion angle. If you do decide to do this, I recommend going ahead and installing the 3/4" spring relocation kit which has offset front hangars and offset shackles. This will allow you to run a wider tire and you have to weld the spring perches in anyway, so why not weld them in the relocated position. With the 8 3/4" you'll also have the option for quick and simple gear ratio swaps.

The photo I've attached is of my old 71 Duster. I installed a pre 71 B-body Dana, SS springs, MP 3/4" spring reloction kit, 10" wide Weld Draglites w/6.5" backspacing and 305 50 15 BFGs. No tub and never a rub.

 

[pishta]

Agree with Rumble....people are scared of the C-clips, but keep in mind that there are tens of millions of C-clip vehicles on the roads:

All non-8.75 Darts
All FMJ bodies
All Dakotas and Durangos ever built
All Rams (including the new ones)

All the Ford 8.8s out there (Mustangs and F-150s, anybody?)

Yeah, there is nothing wrong with C-clips for most applications.

The 8.8 is a nice rear, I was suprised when I took the axles out that the rollers ran right on the axle too, cook an axle bearing and you'll likely damage the axle itself.