8 1/4 gear change?

[streetmachine]

Just curious as its an idea for in the future. I have a '79 Cordoba with a mild 360, A999, and 8 1/4 rear with 2.45 gears. One of my ideas is change the gears out in the rear to say something like a 3.21 or so gear to give the car a little more off the line and for a little fun. This car will be a street car anyways so, I'm curious and what parts I would need to make the change and I'm wondering what the swap would cost me if I had a shop do the brunt of the work? Thank you in advance.

 

[PurpleBeeper]

I used to own a '77 Cordoba....I think you will save money + have a MUCH stronger rearend by swapping the whole thing out for a 8-3/4" with 3.23's. It is practically a bolt-in swap except you might need to figure out which driveshaft to use since the length is probably a little different. I bet you can put in a 8-3/4" cheaper than changing gears.

 

[Kevin Adams]

Just curious as its an idea for in the future. I have a '79 Cordoba with a mild 360, A999, and 8 1/4 rear with 2.45 gears. One of my ideas is change the gears out in the rear to say something like a 3.21 or so gear to give the car a little more off the line and for a little fun. This car will be a street car anyways so, I'm curious and what parts I would need to make the change and I'm wondering what the swap would cost me if I had a shop do the brunt of the work? Thank you in advance.

Hey man! I just built a V-8 Vega hatchback with an 8 1/4 that came from my '73 Dart Swinger. The Dart got an 8 3/4. Since MoPar has been using the 8 1/4 since 1964 in everything including pickups, vans, C-body tuna boats and more recently Durangos, Jeeps and Dakotas, I figured it was a better rear end than a GM unit. It has the same pinion shaft diameter as the Dana 60, 12 bolt GM and 8.8 Ford. But, the 8 1/4 came in two differential support bearing configurations depending on what vehicle it was destined for. A large and a small, which isn't really that small. The difference between the two size bearings is the outside diameter race which fits that specific housing. Everything else is the same. In 1997 MoPar upgraded from the original 27-spline carrier to a 29-spline carrier. To swap a '97 up 29-spline posi carrier is direct using the bearings for your housing. You can use a cut and resplined set of 9 1/4 5-lug axles from a pickup or van to top it off or buy custom axles to fit. I had a set from a van cut and resplined for my Vega by Moser. These give you basically Dana 60 axles. Moser tapers them just before the carrier. The 8 1/4 really is a buildable heavy duty unit. Food for thought.

 

[Kernel Sanders]

As was mentioned it would be cheaper to find an original 71-74B 8.75 or Cbody 8.75 (an tad wider and moving perches) than to have a SHOP change and setup the gears in the 8.25 IMO

If YOU do the job it will be cheaper but as the 8.25 is likely going to be worked on and gears set up under the car it can be a real pain in the ***. IMO

 

[HALIFAXHOPS]

Just curious as its an idea for in the future. I have a '79 Cordoba with a mild 360, A999, and 8 1/4 rear with 2.45 gears. One of my ideas is change the gears out in the rear to say something like a 3.21 or so gear to give the car a little more off the line and for a little fun. This car will be a street car anyways so, I'm curious and what parts I would need to make the change and I'm wondering what the swap would cost me if I had a shop do the brunt of the work? Thank you in advance.

Wont work in that carrier the pinion is offset for the 2.45 and higer gears. We started a thread on this in FABO.

Good info here http://www.forabodiesonly.com/mopar/threads/the-8-1-4-thread.350667/

 

[HALIFAXHOPS]

Hey man! I just built a V-8 Vega hatchback with an 8 1/4 that came from my '73 Dart Swinger. The Dart got an 8 3/4. Since MoPar has been using the 8 1/4 since 1964 in everything including pickups, vans, C-body tuna boats and more recently Durangos, Jeeps and Dakotas, I figured it was a better rear end than a GM unit. It has the same pinion shaft diameter as the Dana 60, 12 bolt GM and 8.8 Ford. But, the 8 1/4 came in two differential support bearing configurations depending on what vehicle it was destined for. A large and a small, which isn't really that small. The difference between the two size bearings is the outside diameter race which fits that specific housing. Everything else is the same. In 1997 MoPar upgraded from the original 27-spline carrier to a 29-spline carrier. To swap a '97 up 29-spline posi carrier is direct using the bearings for your housing. You can use a cut and resplined set of 9 1/4 5-lug axles from a pickup or van to top it off or buy custom axles to fit. I had a set from a van cut and resplined for my Vega by Moser. These give you basically Dana 60 axles. Moser tapers them just before the carrier. The 8 1/4 really is a buildable heavy duty unit. Food for thought.

The two carrier bearings are ouside dia 3.2? and 2.8? Just went through this in my dart.

 

[rumblefish360]

I so (partially) disagree.
The 8-3/4 swap is a stronger rear with a 3rd member advantage BUT you'll have to pay the piper and get the rear first which is not cheap and then anti up again for upgrading the gear ratio.

The 8-1/4 will be fine if your not putting a ton of power into it and/or beating then crap out of it.

Cost wise, the parts are MUCH cheaper.
Price everything out part wise to upgrade each rear as if you had them and then add the cost of purchasing the 8-3/4 on top of it.

Been there done that. (F%€* that!)