How to Swap Budget Disc Brakes Onto a GM 14-bolt Axle


    Evan PerkinsPhotographer, Writer

    Gold, whether struck by luck or skill, is still gold. And whether GM intended the 14-bolt to be the ultimate in affordable, unbreakable axles or it was simply a fluke we’ll never know. Either way, we’re sure glad. The axle came from the factory in more vehicles than we can count. For the average Joe, it’s more than up to the task of big tires, bigger rocks, and even a good bit of power and torque. The only downside is the hefty weight and the limited ground clearance afforded by its massive 10 1/2-inch ring gear—the latter being both a blessing and a curse.

    One way to trim some of the 14-bolt’s pork is a quick and easy disc brake swap. The standard-issue drums are the size of Bigfoot’s food bowl and weigh a ton! It’s a no-brainer to ditch them in favor of lighter, better-stopping, and easily serviceable disc brakes. Another homerun by the GM crowd is the back-and-forth parts compatibility that allows easily sourced front rotors and calipers to be repurposed at the rear. The job can be tackled in the driveway in a few hours. Better yet, it’s a completely bolt-on affair.

    Our 14-bolt specimen came from a 1985 M1028 diesel military truck and has seen its share of miles, abuse, and geographically classified road grime. On the bright side, it came with 4.56 gears and a Detroit Locker. Now being rebuilt for a second life as an off-roader, the first step is to ditch the drums. Follow along as we detail the process of retro-fitting disc brakes.

    Required Parts

    The grand total for our swap was $280 (includes $40 of core charged for the calipers). We left out the couple bucks’ worth of brake fittings since setups will differ and most axles will already have a bulkhead fitting, and in most cases tube nuts and that sort of thing can be reused.

    PartSource VehicleSourcePrice
    Calipers (front)1977 Chevy C20RockAuto$93.58
    Rotors (front)1977 Chevy C20RockAuto$105.58
    Caliper bracketsN/ABallistic Fabrication$39.99
    Brake pads (front)1977 Chevy C20RockAuto$21.79
    Brake hoses (front)1977 Chevy C20RockAuto$15.12
    Hose tabAftermarketSummit Racing Equipment$3.94