8-1/4 Diff Mod

[Denno]

Hi all, I Need Your Guidence! The 72 charger I have brought has a 8-1/4 single spinner diff.
Can I upgrade it while keeping the original housing? I want both wheels powering with good all round Street Gears to get it boogieing.
People here are all "Build a 9" rarrarar! but it's big dollars & I want to keep it genuine Dodge.
Please Advise.

 

[HALIFAXHOPS]

Yes you can what gears are in there now? 2.45 carrier and up your kind of stuck with high gears.

 

[Darter6]

72 carrier should be ok to add a sure grip. Don't let anyone kid you into thinking the 8 1/4''
is a poor rear. Unless you are throwing some real horsepower at it they work just fine.
Cost wise a Spicer Trac-Lok is about the way to go.US cost is around $350-$400.
Then the labor it have it installed. Ball bark figure around $1200 total is what you are looking at.

 

[HALIFAXHOPS]

I run a 8 1/4 with 500 hp. holds up fine. you can steal a sure grip with 3.55 gears out of a late 90.s jeep that has a dana 35 in it. What I did way cheaper.

 

[Denno]

Yes you can what gears are in there now? 2.45 carrier and up your kind of stuck with high gears.

I don't know at the moment mate, it is still on the water heading here. The previous owner said it was a single spin 8 1/2 but didn't mention the ratios.

I run a 8 1/4 with 500 hp. holds up fine. you can steal a sure grip with 3.55 gears out of a late 90.s jeep that has a dana 35 in it. What I did way cheaper.

That's a good idea! thanks mate

 

[Denno]

72 carrier should be ok to add a sure grip. Don't let anyone kid you into thinking the 8 1/4''
is a poor rear. Unless you are throwing some real horsepower at it they work just fine.
Cost wise a Spicer Trac-Lok is about the way to go.US cost is around $350-$400.
Then the labor it have it installed. Ball bark figure around $1200 total is what you are looking at.

That's heaps cheaper than the 9" option & is definitely the way I want to go!

 

[beanhead]

Hi all, I Need Your Guidence! The 72 charger I have brought has a 8-1/4 single spinner diff.
Can I upgrade it while keeping the original housing? I want both wheels powering with good all round Street Gears to get it boogieing.
People here are all "Build a 9" rarrarar! but it's big dollars & I want to keep it genuine Dodge.
Please Advise.

You can definitely upgrade it, but can be tough to find stuff for the 8-1/4. You didn't mention your power/transmission combo, but unless you're making serious oats and have a 4-speed, your diff will hold up fine.
Get in touch with Cass/ Dr.Diff (Montana, USA) he should have diffs and gear sets for that axle.
You have my deepest sympathy on shipping to Oz...

 

[Justasgood]

I have an 8 1/4 that initially had a sure grip 3:73. Engine is a 383 punched .40 over, 11:5 compression, aggressive cam.


Just bought a Ring and pinion to bring the gear to a more streetable 3:21

I see no issue with the 8 1/4

 

[RemCharger]

8 3/4.

 

[Denno]

You can definitely upgrade it, but can be tough to find stuff for the 8-1/4. You didn't mention your power/transmission combo, but unless you're making serious oats and have a 4-speed, your diff will hold up fine.
Get in touch with Cass/ Dr.Diff (Montana, USA) he should have diffs and gear sets for that axle.
You have my deepest sympathy on shipping to Oz...

It runs a 360 Mag & 904 auto, beefy cam but nothing wild

 

[Cranky]

I have a couple of mid 90's Dodge Dakotas (both have the 8 1/4) and one has had nothing but abuse shoved to it with 1600 lb loads and one wheel peels and it's hanging on. Both have 3.55 gears and both trucks have V6's so that might not amount to a hill of beans but taking on 1600 lb loads going down a wavy freeway has gotta say something not to mention how hard I've been to the 95 over the years. Screw that 9" crap!!! They ain't any better than the 8 3/4 in stock form imo and the 8 3/4 is easier to work on.

 

[Darter6]

Get in touch with Cass/ Dr.Diff (Montana, USA) he should have diffs and gear sets for that axle.

Don't know if you have heard of him but he is first class. Also a member here and good to all of us.

 

[1STMP]

Should be no problem with an 8-1/4
lowering the gear with a sure grip.
The thing to safeguard is wheel hop
and the tendency to puke the internals
out the back under hard acceleration.
A girdle will help to control this
tendency.

LPW Chrysler, Dodge, AMC, Jeep ULTIMATE Support Cover, Differential Cover, Rear End Girdle

Strengthen your vehicle's rear end with the strongest rated support covers you can buy! These lightweight aluminum covers strengthen the rear housing from case distortion under load, preventing increased side bearing clearance and ring gear deflection.

www.lpwracing.com

 

[Denno]

Should be no problem with an 8-1/4
lowering the gear with a sure grip.
The thing to safeguard is wheel hop
and the tendency to puke the internals
out the back under hard acceleration.
A girdle will help to control this
tendency.

LPW Chrysler, Dodge, AMC, Jeep ULTIMATE Support Cover, Differential Cover, Rear End Girdle

Strengthen your vehicle's rear end with the strongest rated support covers you can buy! These lightweight aluminum covers strengthen the rear housing from case distortion under load, preventing increased side bearing clearance and ring gear deflection.

www.lpwracing.com

Thank you! Is there a center you would recommend for this? The axles would also be stock, but will buy new ones if needed. i would buy everything then have it shipped & fitted.

 

[1STMP]

Thank you! Is there a center you would recommend for this? The axles would also be stock, but will buy new ones if needed. i would buy everything then have it shipped & fitted.

I modified mine to get rid of the
swivel feet so the screws make
direct contact with the bearing caps.
To this:

From this:

The girdle also helps to reinforce the
case, and finned to help cool the diff
fluid.
You can get the spool from Year One.

Mopar Performance P4529273 8 1/4 Sure Grip Differential A...

YEARONE Classic Car Parts for American Muscle Cars | Barracuda Cuda Challenger Charger Chevelle Road Runner Camaro Super Bee Dart Duster Valiant Firebird GTO Cutlass 442 Mustang Nova GM Truck Skylark GS Monte Carlo El Camino Mopar Chevy

www.yearone.com

Can't attest to it's availability, and you
may have to do some searching to
find one. Early to late '80's Dodge
Diplomat police cars are a good
alternate source besides Jeep's
D-35.
How long it will last is the age old
debate. Beat it hard, it's gonna die.
Block long burn-outs behind a 500hp
440....nope. There were thousands
of these diffs built in the 8-1/4 dress.
Put one of these behind that sanely
driven 440 they'll last you a good
long while.