Starting in 1973, millions of 14 bolt rear axles were produced for use in Chevrolet and GMC trucks and vans, as well as quite a few commercial vehicles. The 14 bolt is revered for its toughness and reliability, and the 14 bolt is particular popular with off-road enthusiasts.
Many people refer to the 14 bolt as the “corporate” axle, and the question is, why? In this article, we’ll explain, and also share some 14 bolt axle history.
Here’s Why The 14 Bolt Is The “Corporate” Axle
To understand why the 14 bolt is called the “corporate” axle, it’s important to understand some things about General Motors:
- In the 1950s and 1960s, each division of GM was fairly independent. This meant, for example, that you’d have a V8 engine designed and developed by Chevrolet, exclusively for use in Chevrolet vehicles. Then Buick would have a V8 engine for their vehicles, Pontiac would have an engine for their vehicles, etc. and so on.
- GM divisions didn’t just develop their own engines – they had division-specific versions of everything. For example, a 10 bolt axle used on a mid-60’s Chevrolet is different than the 10 bolt axle you’d find on a mid-60’s Buick, Olds, or Pontiac. Some parts are interchangeable, some parts aren’t. The same goes for a lot of components – GM divisions were all working from different parts bins.
- Then, in the late 1960s and early 1970s, GM determined that all of these variations were unnecessary and wasteful. So, they started to standardize components across all the divisions to simplify and cut costs.
Which brings us to the “corporate” 14 bolt axle: The corporation headquarters (aka GM) told all the divisions to start using standardized parts. When the 14 bolt axle debuted in 1973, it had been developed under the “corporate” umbrella with GM providing standard design specs for all divisions. This made it a “corporate” axle rather than a division-specific axle. Thus, it became the “corporate” 14 bolt.
GM first built the corporate 14 bolt in Saginaw, Michigan, and eventually spun off the operations in Saginaw to investors who called the new company American Axle & Manufacturing (AAM). Founded in 1994, AAM continues to produce the 14 bolt for GM to this day.
The Different Types of 14 Bolt Axles Throughout the Years
The expression “if it ain’t broke, don’t fix it” largely applies to the 14 bolt axle. While variations have been produced and small changes have been made throughout the years, the basic components and overall design of the 14 bolt axle has been fairly consistent.
In 1973, GM introduced the 14 bolt axle to the world. At that time, it was a “full-float” axle only, with stud-mounted brake drums. The axle was designed for use in heavy duty trucks.
In 1985, the pinion bearing was upgraded to a slightly larger version. This is notable if you have a 14 bolt from this era that you’re trying to upgrade.
In 1986, GM started making both a new “semi-float” style alongside the “full-float” style. This semi float axle had a smaller ring gear (9.5″), as it was designed for lighter vehicles than the larger full float 10.5″ 14 bolt. The semi float came in both an 8 lug and 6 lug configuration, and was mostly available on 3/4 ton trucks and vans from Chevy and GMC. They stopped producing this axle in 1993.
If you’re not sure whether you’ve got a full-float or semi-float axle, this 14 Bolt Axle Identification Chart may help.
In 1988, GM began to offer full-float axles with slide-on brake drums. This style was a little easier to service, as the drum was easier to remove. However, to make things interesting, GM offered both the ‘stud mounted’ drums and the slide-on drums on 14 bolt axles produced in 1988 and later. So, even if you have a relatively new axle, it’s important to check the drum mount type before buying something like one of our brake conversion kits.
GM’s Saginaw axle operations were spun off as a separate business called American Axle and Manufacturing, Inc. (AAM).
AAM began to offer an even beefier version of the 14 bolt axle with an 11.5″ ring gear. However, AAM continues to produce the 14 bolt with the 10.5″ ring gear for GM today. Additionally, GM started to offer the 14 bolt axle with disc brakes rather than drum brakes on the Silverado/Sierra pickup, only they continued to build 14 bolts with drum brakes for vans and other applications.
Chrysler began using the 14 bolt axle on some 3/4 and 1 ton RAM trucks, and did so thru 2013.
Pro Tip: Upgrade the Drum Brakes on Your Old 14 Bolt Axle To Discs
PLEASE NOTE: When it comes to disc brake conversion kits offered by Lugnut4x4, all our kits are intended as bolt-in replacements. This is because our kit is designed to work with the standard OEM brake system (including master cylinder and proportioning valve). As long as you’re installing one of our disc brake conversion kits on an original vehicle application (meaning it’s not an axle swap), the existing brake system will work just fine.
There are lots of great reasons to upgrade the drum brakes on your old 14 bolt axle:
- Drum brakes can be difficult to service, especially on the axles with stud mounted drums.
- Drum brakes don’t have the firm pedal feel of disc brakes, and they tend to fade more quickly than discs.
- Drum brakes don’t stop as well as disc brakes.
To upgrade your drums to discs, you just need to know the specific type of 14 bolt axle you have (full-float or semi-float), and then determine if you have a slide-on or stud-mounted brake drum. Once you know that, you can find all our 14 bolt disc brake conversion kits here.
All our disc brake conversion kits are designed to work with the OEM brake system that came with your vehicle, and the kits include everything you need to complete the swap (well, everything except elbow grease and brake fluid).