Nuts & Bolts: 14-Bolt Disc BrakesPosted in How To: Suspension Brakes on November 30, 2016
I have a 1986 GMC fullsize pickup with 1973 4x4 truck running gear under it. Where can I find more info for a disc brake setup on the rear end?
Your truck’s1973 3/4-ton running gear means that the rear axle is most likely a burly 10.5-inch full-floating 14-bolt. While not completely bulletproof, it’s pretty close even in stock form. Putting disc brakes on a 14-bolt is one of the most common disc brake conversions out there, so you have a number of choices. Both Offroad Design (offroaddesign.com) and Ruffstuff Specialties (ruffstuffspecialties.com) offer a simple kit that includes caliper stands that bolt into place, so no is welding required. We even did an article a while back on the Offroad Design kit, which you can view on our supersite (fourwheeler.com/how-to/transmission-drivetrain/129-1103-14-bolt-disc-brake-conversion/). With both kits, the factory wheel hubs are retained and you source your own calipers (GM 1/2-ton or 3/4-ton calipers are the most common), pads, and brake rotors, all of which are commonly available at your local auto parts store. Both kits will net you disc brakes, but that’s not all you will need. Often longer wheel studs will be required for 3/4-ton rear ends, and you will need to do some plumbing work to attach the calipers to the rest of the brake system. Most of the time you can shorten and reflare the factory hardline that runs along the axle and then attach short flexible lines between the hard line and the calipers. The flexible line is necessary to allow the caliper to move or “float” over the rotor as the brake pads wear. Both companies offer the wheel studs and brake hoses you need as well.
Doing the disc brake conversion is arguably easier than rebuilding the stock drums. You lose over 50 pounds per side, and you net better, more reliable rear brakes. Best of all, the whole swap can be done for well under $500 all-in.