Making The Weak 7-1/4 Rear Axle Live... Kinda

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While I don't recommend welding the spider gears together, or really locking the carrier at all in any way, I will say this. If you run a tall enough tire, you may never know the axles are locked, because the tires will take up some of the shock. I had some L-60/15s on the back of an old Chevelle with a welded up carrier...was like that when I bought it and it never made the tires chirp. When I romped it, it was a different story.
 
RustyRatRod said:
While I don't recommend welding the spider gears together, or really locking the carrier at all in any way, I will say this. If you run a tall enough tire, you may never know the axles are locked, because the tires will take up some of the shock. I had some L-60/15s on the back of an old Chevelle with a welded up carrier...was like that when I bought it and it never made the tires chirp. When I romped it, it was a different story.
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I might try this thing once I get some measurements to see if I can make it fit. The good about these experiments is that I can still get spider gears, so some things I grind and modify.

images.jpeg
 
Ant said:
Howdy!
I have a challenge for my self and would like some constructive input.
I'm building a 318 for my 73 Dart, it should make somewhere in the ballpark of 300HP. It will be bolted to the A904 auto transmission with a stock-ish stall converter. The car's weight is somewhere around 3450 pounds with driver.

So, I don't have a stronger rear yet, so the challenge becomes making the 7.25 rear hold up in the meantime. So far I know the spider gears in the diff are pretty weak, so let's start there. I have some ideas, like:
Welding the spiders together.(May not be good for street use)

Somewhow converting the open diff to a LSD.(Will be lots of research to be done for cheap)

Tuning the car to accelerate softer from a stop.

Not driving like an idiot.

Now before anyone replies with "Go buy a Dana 60 or Ferd 8.8" please understand that this is for fun and I'm not running a torque monster of an engine.
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The welded spyder gears are not for street. Making turns, especialy right, it will tend to hop and chirp the inside tire. The car will want to go straight instead of turn.
An earlier Dakota rear with 8.25 may be an easy conversion. I know they are not overly strong either, but better. Just that road apples 6 bolt pattern they used. Get the axles redrilled for the 5 on 4.5 pattern. Some came with Sure Grip. Later ones even have disc brakes.
 
Ant said:
Howdy!
I have a challenge for my self and would like some constructive input.
I'm building a 318 for my 73 Dart, it should make somewhere in the ballpark of 300HP. It will be bolted to the A904 auto transmission with a stock-ish stall converter. The car's weight is somewhere around 3450 pounds with driver.

So, I don't have a stronger rear yet, so the challenge becomes making the 7.25 rear hold up in the meantime. So far I know the spider gears in the diff are pretty weak, so let's start there. I have some ideas, like:
Welding the spiders together.(May not be good for street use)

Somewhow converting the open diff to a LSD.(Will be lots of research to be done for cheap)

Tuning the car to accelerate softer from a stop.

Not driving like an idiot.

Now before anyone replies with "Go buy a Dana 60 or Ferd 8.8" please understand that this is for fun and I'm not running a torque monster of an engine.
Click to expand...
Drive gently until you find and 8 3/4 but you will have to pony up some bucks I have broken several 7 1/4s with a slant six
 
Just for the sake of conversation.

The offroad VW powered Dune Buggies, we built the transaxle differential with a Super Diff. 4 spider gears instead of 2.

Doubled the strength of them, yet with these we did not need the locking diff as we use Steering Brakes to assist steering in the soft sand terrain.

Also did a nice 280-Z drive shaft conversion that eliminated the weak factory VW CV Joints.

Unbreakable . . .

large-AC301132__32491.jpg


ac301132_2.jpg


Took 4 stock spiders to make it work.

Screenshot_20230520-194152_Firefox.jpg


Brings back a lot of fond memories looking at this again.

Screenshot_20220109-201330_Gallery.jpg


Twin Steering Brake levers at the center console.

Only limited by your imagination.

☆☆☆☆☆
 
George Jets said:
Just for the sake of conversation.

The offroad VW powered Dune Buggies, we built the transaxle differential with a Super Diff. 4 spider gears instead of 2.

Doubled the strength of them, yet with these we did not need the locking diff as we use Steering Brakes to assist steering in the soft sand terrain.

Also did a nice 280-Z drive shaft conversion that eliminated the weak factory VW CV Joints.

Unbreakable . . .

View attachment 1716092388

View attachment 1716092389

Took 4 stock spiders to make it work.

View attachment 1716092390

Brings back a lot of fond memories looking at this again.

View attachment 1716092391

Twin Steering Brake levers at the center console.

Only limited by your imagination.

☆☆☆☆☆
Click to expand...
If I could, I would. That would make it much stronger, but what is available for the Chrysler 7-1/4? I and many others just can't find upgrade parts for them, which seems kinda weird since the 7-1/4 is a very popular rear axle.

I have a few ideas, maybe I'll get another carrier just for doing some experiments.
 
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