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One of the many complaints I’ve had about the Jeep since day one is that the rear brakes and parking brake have never really worked properly. The rear adjusters would always seize up and the brakes would slack off until they really weren’t doing much anymore. Things didn’t improve after swapping the 9" in the rear, either, and so I slowly lost my faith in drum brakes altogether.
Sometime in 2001 I heard about the idea of a transfer-case mounted parking brake. People like Jess at High Angle Driveline have been making them for a while now, but being the cheap SOB I am, I decided to make my own. This would solve my parking brake woes, and keep the Jeep street legal after the new rear rend (which would have no parking brake hookup) was installed. You can read about that project here.
There are a few advantages to putting your parking brake onto the back of your transfer case. First, since the brake is located before the differential, it has to apply a lot less force to stop the vehicle. That means it can be a lot smaller than a conventional brake, and still do the same amount of work. Also, the transfer case location is up and out of the way, so no more long articulation-limiting rock-snagging brake cables to worry about. The only down side is that under certain conditions, the brake may not hold the vehicle still. In a truck with an open diff, both rear wheels need to have traction when the brake is on or else the differential will allow them to turn (in opposite directions), and the truck will move.
Building a transfer-case mounted parking brake turned out to be a surprising amount of fabrication work and parts hunting. The key components are these:
1. A rotor. There are two options here: either make one out of plate steel, or use a motorcycle brake rotor. Lacking a lathe, I chose the motorcycle rotor option. A local bike parts place was going out of business, so I picked up a couple of different sizes for cheap. The trick in picking a bike rotor is to find one between 6" and 8" across, with a big enough hole in the centre to fit around the transfer case yoke.
2. A caliper. There are a few options out there for mechanical calipers. Most of them are small ones, designed for use on go-karts. This type (spot calipers) are actually okay for use as parking brakes on vehicles, but they probably won’t stand up to extended use as emergency brakes. There are also larger ones, but they get expensive in a hurry. Here’s a link to the one I chose.
3. A caliper bracket. Here’s where the fabrication comes in. I made my bracket out of various bits of steel tubing and bar stock, and a lot of welding wire.
Once the rotor and caliper are chosen, the bracket can be built. Depending on the transfer case, there are probably several options for how to attach the bracket to the case. My D20 has a nice flat inspection cover that made an ideal base for the bracket. Having a spare case makes building the bracket a LOT easier, since you can use it as a jig for building it on.
In my case, the rotor is attached to the back of the rear output yoke with a pair of steel tie plates that I made up. These plates adapt the bolt pattern of the yoke to the bolt pattern of the rotor. Unfortunately, the hole in my rotor isn’t quite large enough for it to fit over the large end of the yoke, so I have to remove the yoke in order to get the rotor on. It was very important to make the tie plates symmetric, so the rotor ends up balanced on the yoke. Grinding the tie plates so that they clear the ridges on the backside of the yoke is also a bit tricky. I used a dial indicator to adjust the rotor position for minimal runout.
The rotor attaches to the yoke using the four bolts that fasten the driveshaft to the yoke.
Once the rotor was in place on my spare case, I started building the caliper bracket. The bracket is basically a piece of rectangular tubing cut so the caliper ends up in the right place on the rotor. I ended up adding a piece of steel plate in between the bracket and the transfer case inspection cover, to move the caliper to the right spot on the rotor.
Here’s some pics of all this stuff. First is the rotor and the tieplates that attach it to the yoke.
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Next is the caliper bracket and caliper, shown assembled on my spare case and then in the Jeep:
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Finally, here’s how the parking brake cable is hooked up, with its return spring:
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The parking brake cable is from an 8.8" rear end, out of a Ranger or Explorer. This cable happened to be roughly the length I needed, but most important the ends were right. It hooked up perfectly to the e-brake pedal. The return spring is necessary to get the pedal back up again when you release the brake. The little cup-shaped piece connecting the cable to the caliper is part of a later-model YJ’s parking brake adjuster assembly.
Once I got it installed and adjusted, I found the brake worked pretty well over all. The pedal pressure needed to keep the truck stopped on an incline was very light, and it has no problem bringing the Jeep to a halt at low speeds. Unfortunately, the steel slider bracket that the caliper sits in loosened up pretty quickly, allowing the caliper to cock sideways and jam against the rotor. I’ll be modifying the bracket soon with a new caliper slider mechanism that uses the two bolt holes that go through the caliper.
Questions? Email me!
