A Little History
Wondering what axles your Bronco came with? Here's a little helper.
Front
Axle: Dana 30
Found In: '66-'711/2 models
Notes: Drum brakes, small 260X-sized U-joints. Can be upgraded with aftermarket shafts and disc brakes, but it's better in the long run to swap in a later Bronco Dana 44.
Axle: Dana 44
Found In: '711/2-'75 models
Notes: Drum brakes, 297X/760X-sized U-joints. Six-bolt spindles easily converted to disc brakes. '711/2-'721/2 spindles utilize outer axle seal that presses into back of spindle. '721/2-'75 utilize outer seal that presses onto stub shaft.
Axle: Dana 44
Found In: '76-'77 models
Notes: Disc brakes, 297X/760X-sized U-joints. Five-bolt spindles are unique to '76-'79 Ford 1/2-ton Dana 44 axles so crossover of brands (Chevy/Dodge/Jeep) not possible.
Rear
Axle: Ford 9-inch
Found In: '65-'75 model
Notes: Small bearing housing ends with 3/8 bolts (backing-plate mounting-hole measurements 35/16x2 inches). 10x21/2-inch drum brakes. Driver-side shaft length 271/8 inches; passenger-side length 295/8 inches.
Axle: Ford 9-inch
Found In: '74-'75 models
Notes: Medium duty, large bearing housing ends with 3/8 bolts (backing-plate mounting-hole measurements 39/16 x 2 inches). 10x21/2-inch drum brakes. Driver-side shaft length 271/4 inches; passenger-side length 293/4 inches.
Axle: Ford 9-inch
Found In: '66-'75 models
Notes: Standard duty, large bearing housing ends with 1/2-inch bolts (backing-plate mounting-hole measurements 31/2x23/8 inches). 11x13/4-inch drum brakes. Driver-side shaft length 2615/16 inches; passenger-side shaft length 291/4 inches.
Axle: Ford 9-inch
Found In: '76-'77 models
Notes: Heavy-duty housing, large bearing housing ends with 1/2-inch bolts (backing-plate mounting-hole measurements 31/2x23/8 inch). 11x21/4 inch drum brakes. Driver-side shaft length 273/16 inches; passenger-side shaft length 2911/16 inches.
Rear Axle Upgrades
Although the '76-'77 heavy-duty housings left the factory with larger 31-spline shafts, most Broncos are packing spindly 28-spline shafts. While they'll do for moderate wheeling, it's a sure snap in the making to run them with big tires and a locker in the rocks. Once again, Drivetrain Warehouse had the parts in stock we needed to upgrade not only the shafts but the factory gray steel carrier as well.
The third member arrived with...
The third member arrived with the Genuine Gear G2 ring-and-pinion all set up on a Detroit Locker and ready to drop in. Again, check the beefy carrier caps and overall quality of the 9-plus case.
Check the sidebar, "A Little...
Check the sidebar, "A Little History" for more information about determining exactly which 9-inch you've got. It's important to know since Broncos used four different housings, and each one uses a different length axleshaft. We opted for Genuine Gear's new G2 line of 31-spline alloy axleshafts. The splines are rolled, not cut, into the shaft and feature induction hardening for strength and torsional flexibility.
It's an often-forgotten component...
It's an often-forgotten component when it comes to upgrading, but unless it's sporting a big "N" above the pinion, the factory third member casting is a relatively low-grade gray iron that can crack with big power or the stress of big tires. Drivetrain Warehouse sent us an assembled third member built with a Currie Enterprises 9-Plus nodular-iron centersection. In addition to the better material, the improved housing also has more webbing and thicker surfaces where it counts for performance applications.
The Five-Bolt Curse
When we decided to convert our buddy's front axle from six-bolt to five-bolt we didn't know what we were getting ourselves into. We thought we'd just drop by the local wrecking yard and nab the five-bolt spindles, backing plates, and other stuff we'd need to make the swap. Long story short, after much scrounging through boneyards, craigslist, and eBay, we dropped by Jeff's Bronco Graveyard. That is to say, we dropped by Jeff's Web site. There, staring us in the face was a complete kit for the five-bolt Ford Dana 44 axle with everything we'd need and more. The company is super-knowledgeable about these trucks and quickly had everything we needed out the door to us.
The Jeff's Bronco Graveyard Extreme Outer Rebuild Kit (PN 12213) included everything we needed to convert our buddy's six-bolt Dana 44 with the exception of the caliper brackets. But wouldn't you know, JBG had a set of those as well. The kit is too nice for words, and includes new spindles, Timken bearings, seals, studs, ball joints, calipers, high-performance cross-drilled and slotted rotors, spindle nuts and washers, and everything else you see in the photo.