Super 14 Bolt Axle - 4-Wheel & Off-Road Magazine

Fred Williams Brand Manager, Petersen’s 4Wheel & Off Road

The Super 14 is a new suit for the good ol' GM Corporate 14-bolt axle. The GM 14-bolt is a great rear axle because it is strong, has many gear ratios, and has various types of lockers and limited slip differentials available. In addition, used 14-bolts are often dirt-cheap, making them a great low-buck upgrade for big tires on your trail rig.


gm Coporate Leaner Super 14 Bolt Axle dedicated Off Road Racer Photo 29163835

Of course there is a price to pay for all these benefits. For one, it is heavy, and less weight is almost always a good idea for a trail rig. Also, the 14-bolt's ground clearance isn't great, as the centersection has a low-hanging lip. The Super 14 addresses both these issues and turns your heavy 1-ton axle into a sleek go-fast race rearend.

gm Coporate Leaner Super 14 Bolt Axle axle Photo 29163901 The Corporate 14-bolt is found in many different General Motors 3/4- and 1-ton trucks and vans. 14-bolts have a Gross Axle Weight Rating (GAWR) of 5,700 to 7,500 pounds depending on application, and they use a 101/2-inch ring gear with 11/2-inch 30-spline axleshafts. Though a light-duty semifloat 14-bolt with a smaller ring gear is found in some light-duty 3/4-tons, we are concentrating on the full-float version found in the heavy-duty trucks.

We went through the steps to make a dirty junkyard 14-bolt into a lighter, leaner Super 14 at Superior Axle & Gear. There are many options to build a Super 14, with hi-zoot shafts, special lockers, and TIG-welded chromoly housings, but our plan was taking off-the-shelf parts and seeing what we could gain (or lose) by going from a used Corporate to the Super 14.

Is It Worth It?
The Super 14 can save you between 32 and 97 pounds from a basic Corporate 14-bolt. There are also lighter-weight brake and hub options. But weight savings isn't the only plus for the Super 14; ground clearance also surpasses the Corp. version by 13/8 inches of smooth bottom ground clearance. Plus, the fabricated steel housing is much more versatile for welding axle trusses and link mounts to versus the cast centersection of a Corporate 14. However, the low pinion gearing of a 14-bolt still applies, but with this much axle 40-inch tires are easily in your future. Superior is selling a builder kit for approximately $1,950 with housing and third member. It is up to you to decide if the price is worth the benefits. We think if you're looking for a lighter, faster rearend then it definitely is.

gm Coporate Leaner Super 14 Bolt Axle rear Axle Photo 29163925 PhotosView Slideshow When outfitted with an open carrier, drum brakes, and stock axles and hubs, this 14-bolt from a mid-'80s Chevy weighed in at 428 pounds. This rearend has a 67-inch surface width from wheel mounting surface to wheel mounting surface (WMS to WMS) and 33/8-inch axletubes.
By removing the drum brakes and adding an Offroad Design disc brake conversion, we lost 65 pounds to a total of 363 pounds; but different 14s used different drums so the weight loss varies depending on which axle you start with. The disc brake conversions use front calipers and eight-lug rotors from a '73-'87 3/4-ton Chevy 4x4 truck or Suburban.
The Super 14-bolt is a dropout-style axle that uses a Super 14 aluminum carrier housing and a fabricated axlehousing. We built our axle with an 85-pound fabricated housing (bottom) with 31/2-inch tube, but set it up to use the factory axleshafts and hubs from the 67-inch '80s 1-ton Chevy housing (top). There is also a highly trussed 123-pound chromoly Super 14 housing available from Tubeworks (middle) that uses giant spindles, hubs, 4-inch tubes, and special preload bolts that support the side bearing caps, but it is more of a dedicated race axle.
PhotosView Slideshow The Super 14 carrier housing is cast aluminum for weight savings. We used the basic design, but there is a motorsports version with additional bracing across the bearing caps as well as optional load bolts that support the ring gear from deflecting under heavy load.
The Superior technicians set up the Super 14 third with a set of Superior 5.13 gears and spool. We chose the spool for its light weight and rock-stupid simplicity (left); however, one benefit of a dropout-style axle is the ease of setting up gears and lockers, such as an ARB Air Locker (right) without having to wrestle with the entire housing. The Super 14 uses standard 14-bolt bearings and races.
The 14-bolt uses three pinion support bearings to better locate the pinion against the ring gear. There is a small bearing that the tip of the pinion fits into and two on the pinion shaft. This requires a removable pinion support to install the pinion in both the standard 14-bolt and the Super 14.
PhotosView Slideshow The spool we're running in our Super 14 weighs 27 pounds; an open 14-bolt carrier is 31 pounds. A 14-bolt Detroit Locker replaces the spider gears inside the open carrier and combines to weigh 30.95 pounds. ARB also offers an Air Locker for the 14-bolt, and it weighs approximately 45 pounds.
The Super 14 housing comes with a fabricated centersection made of 3/8-inch plate on the face and 1/4-inch-thick plate for the curved body. Axletubes are 31/2 inches in diameter and available in either 1/4- or 3/8-inch wall thickness.
To use our junkyard axleshafts and hubs, first measure from the overall width and the pinion centerline to the spindle opening of the junkyard axle. Then duplicate those measurements with the Super 14 carrier housing in the fabricated housing with the Spyntec spindles.
PhotosView Slideshow Aligning the spindles in the housing is tricky. The Spyntec spindles are a tight fit, and this should be enough to align them perfectly from side to side through the differential. However, it is not a bad idea to take the housing to a professional axle shop for alignment and final weld. The fabricated housing with brake stands, fill plug, and spindle weighs 85 pounds; the Corp. 14 housing is 141 pounds.
The completed Super 14 axle with gears; bearings; a spool; stock axleshafts; weld-on Offroad Design's disc brake stands, disc brakes, and caliper; and the housing has a final weight of 326 pounds. The drum-brake and disc-brake Corporate 14s weigh 358 and 423 pounds, respectively.