Ford 8.8 Axle Swap
After much research and debate I've decided I'm going to give my Dart a new rear axle, but due to the increasing scarcity of proper, vintage A-body MOPAR 8-1/4 and 8-3/4 axles I'm going to use a much more common and readily available Ford 8.8 axle from a Ford Explorer.
So why the Ford 8.8? There are many good reasons for this axle choice but one right off the top is that these axles are very, very common in junkyards right now (2018).
Why the Explorer as the donor vehicle? There are 4 reasons:
1 - You get a choice of drum or disc brakes depending on the year of the donor vehicle. Pre-95 Explorers have 10" (10x2.5) drum brakes, and 95 and newer vehicles have disc brakes.
2 - The Explorer axle is the stronger version with 31-spline axle shafts. Earlier versions and versions used in applications like some mustangs and rangers used weaker 28-spline axle shafts (though likely still adequate for a slant 6). The 31-spline shafts are larger in diameter and the axle tubes are larger in diameter.
3 - The axle is not symmetric/equal length, the driver's side axle tube is longer than the passenger side by 2-7/8 inches. If you cut the driver's side axle tube down by 2-7/8 inches, you can use two passenger side axle shafts and you have an equal length axle. Relocate some spring perches and it will mount into the '64 Dart on the stock 2-1/2in wide leaf springs.
4 - You can get limited slip diffs. It is very common to find Explorers with limited slip differentials. Look for a door tag axle code starting with a D (like D1, D2, D3, D4) or look for an 'L' on the metal axle tag (should be held on by one of the diff cover bolts). If the tag states # L ## (example 3 L 73) then the axle has a limited slip. My example axle would have a 3.73 gear ratio and a limited slip.
But what are my motivations for doing this?
My primary motivation actually has nothing to do with the MOPAR 7-1/4 axle's reputation for being fragile. It actually has more to do with setting up the rear of the car with 5x4.5in bolt pattern hubs. That way when I put a front disc conversion kit from CPP on the front of the car I will have matching 5x4.5in pattern hubs in all positions.
So why the Ford 8.8? There are many good reasons for this axle choice but one right off the top is that these axles are very, very common in junkyards right now (2018).
Why the Explorer as the donor vehicle? There are 4 reasons:
1 - You get a choice of drum or disc brakes depending on the year of the donor vehicle. Pre-95 Explorers have 10" (10x2.5) drum brakes, and 95 and newer vehicles have disc brakes.
2 - The Explorer axle is the stronger version with 31-spline axle shafts. Earlier versions and versions used in applications like some mustangs and rangers used weaker 28-spline axle shafts (though likely still adequate for a slant 6). The 31-spline shafts are larger in diameter and the axle tubes are larger in diameter.
3 - The axle is not symmetric/equal length, the driver's side axle tube is longer than the passenger side by 2-7/8 inches. If you cut the driver's side axle tube down by 2-7/8 inches, you can use two passenger side axle shafts and you have an equal length axle. Relocate some spring perches and it will mount into the '64 Dart on the stock 2-1/2in wide leaf springs.
4 - You can get limited slip diffs. It is very common to find Explorers with limited slip differentials. Look for a door tag axle code starting with a D (like D1, D2, D3, D4) or look for an 'L' on the metal axle tag (should be held on by one of the diff cover bolts). If the tag states # L ## (example 3 L 73) then the axle has a limited slip. My example axle would have a 3.73 gear ratio and a limited slip.
But what are my motivations for doing this?
My primary motivation actually has nothing to do with the MOPAR 7-1/4 axle's reputation for being fragile. It actually has more to do with setting up the rear of the car with 5x4.5in bolt pattern hubs. That way when I put a front disc conversion kit from CPP on the front of the car I will have matching 5x4.5in pattern hubs in all positions.