Modified Mustangs & Fords
Rear Disc Brakes Conversion
SVO's Bolt-On Rear Disc Brake Conversion Kit For 9-Inch Fords
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Disc brakes on the rear axle of a car are impressive for many reasons, but usually their cost keeps the majority of enthusiasts in drum brakes. Recently, Ford Motorsport Performance Parts made a new kit available, reasonably priced, that comes with everything you need to bolt disc brakes on a Ford 9-inch or 8.8-inch big-car or truck rearend (or any rearend with the correct housing ends on it). Although the kit is very straightforward to installas you will see when Ford-rearend specialist Currie Enterprises in Anaheim, California, installs a kit on a 9-inchmany tips and tricks shown here will make the job easier when you decide to install this kit on your own.
What Is Needed?
The five-lug brake kit uses an 11-inch solid rear rotor clamped by a single-piston floating caliper. The parking brake mechanism uses the hub of the rotor as a brake drum, so it is hidden under the rotor. This design looks clean from the outside but still offers the safety of a parking brake system. The kit is actually the rear brake setup straight off the Ford Explorer 8.8-inch rearend, so the components are proven on the streetin case you doubted that a solid rotor could handle the punishment.
The keys to bolting on this kit are the housing ends and the axles on the rearend. This kit is designed to bolt on to a truck or big-car housing end because the backing plate/caliper mount for the disc brake kit has a 2x3.56-inch bolt pattern, which corresponds to the 9- and 8.8-inch truck and big-car housing ends. Also, the axles need to be a minimum length from the bearing surface to the wheel flange to provide enough clearance for the parking-brake mechanism. There are plenty of Ford rearends that meet these requirements, and if you dont start with one of these, Currie can modify your existing rearend to work with this kit.
According to Currie, this kit will be a direct bolt-on to rearends from 7379 big passenger cars and 7786 pickup trucks. An easy way to identify the ends is to look for 3/8-inch bolts on the housing ends versus the ½-inch bolts used on the other rearends. Currie calls all of these Torino housings. If you dont know if you have one of these rearends, check out the photos of the housing ends needed and the dimensions of the axles. With this infomation, you can decide what youll need to do the job.
Installing the Kit
In our example, the rearend did not have the correct housing ends, and the axles were too narrow to clear the parking-brake assembly. This was good and bad, because it made us go through every step necessary to bolt on this kit, but it also added cost in parts and labor. A lot was learned from this situation, which is included in the story, so we are hopefulthat it will make your life easier when you decide to install this kit.
This Ford 9-inch rearend was from a 5772 Ford car. It has big-bearing ends with ½-inch holes. The rearend had big drum brakes that were able to stop the car just fine, but the drum brakes didnt look good through the aftermarket wheels, so the owner had been looking for a reasonably priced, clean reardisc-brake kit that offered good stopping power. He felt this new kit fit the bill perfectly.
Unfortunately, this rearend needed new ends, at a cost of $49.95 (from Currie), plus $89.95 for Currie to cut off the old ones and weld on the Torino ends. This rearend also needed to be narrowed, included in the $89.95, and new spring pads needed to be welded on, which cost $26.95 to install. The stock axles were replaced with Currie forged-alloy axles. Check the photo of the axle dimensions to understand why the axles needed to be swapped. The axles cost $299.95 for the pair, cut to fit. All this expense should encourage you to find a rearend with the proper housing ends and axles. Even if you need to have the housing and the axles narrowed, its best to start with the right components.
All the steps to installing the brake kit are covered here. The installation of the brake lines and the parking-brake cable will be a custom application for your vehicle, so they are not shown. You could probably modify the existing brake lines to mate with the disc brake calipers, but the safest method is to bend up new lines. Making new brake lines requires a double-flaring tool, a tubing bender, and new line and fittings. The parking-brake levers and cable anchors that come out of the backing plates accept many different cables, so the factory parking-brake cable on your car (whether it is a Ford or not) may work. Also, the backing plates can be swapped to locate the parkig-brake lever either above or below the tubes on the housing to clear springs, shocks, or any other interference problems.