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Best Rear Axles

Posted in How To: Body Chassis on December 1, 2006 Comment (0)
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Best Rear Axles
Contributors: Alan Huber

Whenever we put together a list of "best" or "top," we know we're in for some trouble. So, to try to diminish the rolling of eyes and the letters of hatred, we'd like to begin by saying that these may not actually be our favorite axles. There is indeed a difference between best and favorite. Take the Rockwell-why can't we forget you? Big, heavy, expensive, impractical in many cases-yet cool. But not here.

What we have defined as the best are ones you should consider because they are readily available (junkyard or aftermarket), easy or sensible swaps, and all-around decent pieces of hardware. But don't just take our word for it-we also asked industry experts to weigh in on our picks. And just as it was the case with us, these may not be their 10 favorites either. We forced them to have no further opinion beyond ours.

Some vehicles that came with it: Jeep, Chevy, Ford, International, Dodge, Isuzu.
ID it: Looks like a baby Dana 60; 10-bolt cover.
Good for: Downsize Jeeps, Scouts, Samurais, Cruisers, minitrucks, or S-10 Blazers that will have 36-inch or smaller tires (it's not a heavy-duty axle) and that are currently sporting the AMC or little Dana axles; also, a Toyota solid-axle conversion.
What's to like: 30-spline axleshafts, 8.5-inch ring-and-pinion, better bearing design than the smaller Danas and AMC, and decent ground clearance. Plus, lots of aftermarket parts. Get a Rubicon Dana 44 housing from a Jeep dealership for around $800.
What's not: Bolt-in, but not a full-floater. Tire-size limitations.
Make it better: Scott Frary from Eaton/Detroit Locker recommends aftermarket alloy axleshafts if you're planning on 35 inches or more of rubber. Ray Currie from Currie Enterprises said the company's own 44s have 9-inch Ford-style housing ends with large-bearing-style axleshafts for boosting strength and bearing payload, and for offering more brake options.

Some vehicles that came with it: Ford Explorer, F-150, Ranger, Aerostar, and Bronco.
ID it: Diff cover has 10 bolts and a round-square shape (it makes sense); 8.8-inch ring gear.
Good for: Jeep YJ Wranglers and Cherokees with the rear Dana 35 (31 splines versus 27).
What's to like: It's almost a complete bolt-in for the leaf-spring YJ or XJ-width is nearly identical and the lug patterns are the same-save for some suspension bracketry. Going with the Explorer 8.8 can also get you disc brakes, as many of the 8.8s were factory equipped.
What's not: Jon Mullenhour from West Coast Differentials said you probably won't like the wear that's common, the C-clip, or the Trac-Lok. Frary notes that the coil springs in the '97-and-later Wranglers make installation more of a challenge.
Make it better: Anthony Santure from Reider Racing recommended a good and reasonably priced upgrade: a reinforced girdle cover and/or chromoly axleshafts (plus a Precision Gear ring-and-pinion).

Some vehicles that came with it: GM pickups and vans, Blazer.
ID it: 12-bolt diff cover.
Good for: When would you recommend a 12-bolt as an upgrade? Anyone with a 10-bolt truck that doesn't want eight lugs was the fighting answer for why this axle is here. It's strong and reliable and has tons of aftermarket parts to fix what isn't. Currie added, "It can be swapped into Chevy trucks and Blazers that were originally equipped with 10-bolt GM rearends for those who want to keep their GM vehicle all GM."
What's to like: It has 30-spline axleshafts and a decent 8.875-inch ring-and-pinion (the 10-bolt has 28 splines and an 8.5-inch ring gear). Plus the width, lug pattern, and bracketry make it an easy exchange for a 10-bolt.
What's not: 35s are about as big as you can go. And it has a C-clip design (though it can be eliminated with a kit from Moser).
Make it better: Currie suggests the 9-inch housing-end upgrade to get rid of the C-clips, plus you'll increase the brake choices.

Some vehicles that came with it: 3/4- and 1-ton Dodges and GM dualies.
ID it: 10-bolt cover, more webbing than the Dana 60.
Good for: Diesel power, lots of torque, big tires.
What's to like: 10.50-inch ring gear, big tubes, 23-, 32- and 35-spline axleshafts, and up to 7.71 gearing-bring on the 44s.
What's not: It's really heavy.
Make it better: You may want to swap out the big drums for discs and upgrade the axleshafts if you have the 23- or 32-spline versions.

Some vehicles that came with it: 1/2-ton and 3/4-ton Dodges.
ID it: 12-bolt cover that looks like a stop sign, 9.25 ring-gear diameter, C-clip, and five lugs for 1/2-tons, eight lugs for 3/4-ton vans.
Good for: As a replacement for the smaller-ring-geared Chrysler axles.
What's to like: The largest common 1/2-ton axle you can get.
What's not: 4.88 is the lowest ratio, and it has a limited number of locker choices.
Make it better: Add a Detroit Locker, Auburn Gear, or something in place of the Trac-Lok. Mullenhour said you might think about using 31-spline 9-inch axleshafts and housing ends.

Some vehicles that came with it: 3/4- and 1-ton Fords.
ID it: It has 12 bolts on the cover, 35-spline axles, and a 10.25-inch ring-gear diameter.
Good for: One could argue why this is on the list-but if you're considering a Dana 70 or 14-bolt, consider this one too.
What's to like: Large carrier bearings, a thick case, and thick axletubes. If you have a 1/2-ton that needs to be a full-floater and/or you want a larger towing capacity, consider the Sterling.
What's not: It weighs a ton. Parts are expensive. There are not many ratio choices. Some have a goofy metric 8-on-170mm; tubes also need to be welded to pumpkin to prevent centersection spin.
Make it better: Find a '99-or-newer for the disc brakes.

Some vehicles that came with it: 3/4- and 1-ton GM trucks.
ID it: It has a 14-bolt cover and six-bolt dropout pinion.
Good for: Any Chevy 1/2-ton with big tires and big power.
What's to like: For beef, it's competitive with the Dana 70 and Sterling. It has a large 10.5-inch ring-gear diameter (the smaller 14-bolt has 9.5 diameter and a more rounded cover), 1 1/2-inch 30-spline axleshafts, and a six-bolt removable pinion support, so you don't have to pull off the rear cover plate to get to the pinion. A contender for towing or a high-torque application. And you can find it really cheap.
What's not: The weight of a beast. And still-only 1 1/2-inch 30 splines despite it being GM's finest.
Make it better: Add disc brakes and shave the centersection for clearance.

Some vehicles that came with it: Fullsize Fords.
ID it: Round, with front dropout third member and no back cover.
Good for: Both high-performance (motorsports) and off-road vehicles. Consider it for 1/2-ton trucks that will be running up to 35-inchers or skinny 37s.
What's to like: No C-clip, three pinion bearings (two is typical).
What's not: Mullenhour said it's the extra torque needed to turn it.
Make it better: Currie Enterprises is the king of 9-inch axles, so you can shop for heavier housings, upgraded third members, a performance version, and brake kits.

Some vehicles that came with it: Toyota four-by pickups, 4Runner.
ID it: Round, dropout-style semi-floater.
Good for: An IFS Toyota, a light-duty Chevy pickup (because it has the same six-lug bolt pattern and 30-spline shafts), and a Suzuki Samurai. "The '85-and-older solid-axle front is a good upgrade into an '86-and-later IFS truck," Santure told us. "A person who uses his truck for heavy-duty off-roading with big tires will often sacrifice the smooth carlike ride of his IFS front for the stronger, solid-axle 8-inch front."
What's to like: "It's a very rugged axle for its size," he added.
What's not: Three words-front Birfield joints.
Make it better: A Birfield-eliminator kit or aftermarket alloy Birfields. And add 4.88s, 5.29s, or 5.71s. Mullenhour recommends making the rear a full-floater with Dana 60 30-spline outers and axleshafts.

Some vehicles that came with it: Fords, GMs, and Dodges.
ID it: Extra-large Dana 44. Has a 10-bolt cover and 9.75-inch ring gear.
Good for: Anything with a Dana 44 that needs more heavy-dutyness to run 37s or bigger.
What's to like: Currie recommends a cast center, large-diameter with strong wall tubes, and the big ring-and-pinion. The driver-side high-pinion, reverse-rotation axle from '77-'79 Ford F-250s and F-350s is the Holy Grail of housings for four-wheeling and towing. There's also the 35-spline shafts and up to 7.71 gearing.
What's not: First, it's really heavy. Second, Jim McGean of Dynatrac pointed out that some early 60s had odd parts that are now obsolete and have zero aftermarket support. Also, there's the Dana 50 introduced in the '99 Super Duty that looks just like the 60, so you want to avoid that mistake. Look at the pinion nut. The 60s requires a 15/16-inch socket; the 50s, a 1 1/8-inch. Plus, if you have anything but a fullsize truck, it might need to be narrowed and the suspension bracketry might not fit without some case-machining.
Make it better: Currie's RockJock aluminum 60R housing is strong and allows the same internal components-but is a third of the weight. The dualie front 60 in '77-'92 GM 1-ton pickups ('87-'92 Crew Cabs only) can be converted to single-wheel hubs using parts from Dynatrac.

Sources

Currie Enterprises
Corona, CA 92880
714-528-6957
http://www.currieenterprises.com
Dynatrac
Huntington Beach, CA 92647
714-596-4461
www.dynatrac.com
West Coast Differentials
Rancho Cordova, CA 95742
916-635-0950
http://www.differentials.com
Eaton/Detroit Locker
www.eatonperformance.com

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