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Stop Your Jeep CJ Faster

Posted in How To: Suspension Brakes on December 21, 2018
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The nostalgia and feel of driving an older Jeep on a nice day is quite special. On the other hand, stopping that older Jeep with front drum brakes can be a little too much of a throwback experience. Under panic braking, you may be asking yourself two questions: Will I stop this Jeep in time and will I still be in the same traffic lane when I do?

There are several downsides to front drum brakes when compared to disc systems. Adjusting front drums can be bothersome and, in our experience, they often want to pull one way or the other upon hard braking. With the drums hiding the brake shoes and other components, it can be difficult to see leaking fluids inside that can contaminate the shoes and cause braking problems. If you dunk your front axle in mud and other muck, dirt and gravel may find their way into your drums, affecting braking behavior. Disc brakes don’t really suffer from this problem because the brake rotor is open and the foreign debris can escape easier.

The front brakes on a vehicle provide the majority of the stopping power, so an improvement on this axle can make a significant change in overall braking performance. Disc brakes also do not fade as quickly under hard braking as drum brakes do. It was these motivating factors that prompted the owner of this 1976 CJ-5 to upgrade the front Dana 30 brakes.

Jeep started offering factory disc brakes about the time this CJ-5 was built, so it’s possible to do the conversion using stock parts from that era. However, the price of these salvage axles has risen considerably, and the parts seem to be harder to find these days, with the caliper brackets being the most sought-after piece for the swap.

Summit Racing offers a complete drum-to-disc SSBC Performance Brake Systems conversion kit from for these early Jeeps. It includes almost everything needed for the installation. The conversion is easily done as a driveway project in a single day using common mechanic tools; however, the Dana 30 axle did require a 2 1/16-inch hex socket for the spindle nuts.

With the new discs, the Jeep stops straighter on a more consistent basis, and we know the front brakes will require less maintenance. Stay tuned and we’ll soon be detailing another upgrade to the brakes when we step up to vacuum-boosted power brakes.

Here’s where we started: a mid-70s Dana 30 axle. It’s got Warn hubs and an air locker inside, but the steering brakes are all vintage-era components.
The disc-conversion kit comes complete with calipers and mounts, rotors, a master cylinder, braided stainless steel hoses, seals, and assembly hardware.
The front drum brakes weren’t shot, but they weren’t delivering the necessary performance. We started the conversion by removing the heavy drums.
Locking hubs were removed, revealing the spindle nuts that secure the wheel hub. With those removed, the wheel hub was pulled from the axle.
The last disassembly step on the axle was removing the complete brake backing plate and all its components. It was held to the knuckle with six studs and nuts. At this point, we did a quick check of the knuckle condition. We found all the ball joints in good condition, so we didn’t dig any deeper into the axle.
The old rubber brake lines might have been the original ones. They weren't leaking, but their outer layers were decomposing, so it was a good time for their replacement.
The stock master cylinder was removed. It was disconnected from the brake pedal and unbolted from the firewall after the two hard lines were removed. Jp Pro Tip: We used an air hose and applied low-pressure air to the front brake line to push the old, contaminated fluid out of the lower lines before installing the new brake parts.
We took the stock wheel hubs and replaced the lug studs with new ones provided in the kit. It’s possible to do this with a hammer, but a shop press ensures smooth installation and the confidence that each stud is fully seated.
We checked all the wheel bearings, found them to be in good condition, and simply regreased them. A new seal was installed in the rear of each of the wheel hubs.
The new brake caliper brackets were bolted to each knuckle. They face rearward and each positions its caliper just above the centerline of the axle. Then, each wheel hub could be reinstalled.
We’ve seen a lot of mistakes made bolting the wheel hub back on the spindle. Consult a shop manual if you’re unsure of the assembly. The inner spindle nut also sets the wheel bearing preload.
New SSBC rotors were slipped onto the wheel hubs.
The disc brake calipers are reliable single-piston floating units. Jp Pro Tip: Before installation, we gave each a solid coat of caliper paint to retard rusting of the bare metal casting.
The calipers come preloaded with brake pads and were easily secured to the caliper mounts with two bolts. We also had painted the non-braking surfaces of the rotors to prevent rust there.
We installed the provided DOT-approved stainless brake lines, positioning them to avoid any contact with the nearby shock or tire. We anchored the frame end in the stock bracket but had to make a small modification and use extra clips not included in the kit to secure the lines to the bracket.
This Jeep runs 15-inch aftermarket steel wheels, and our post-install test-fit revealed the inside of the wheel contacted the pointed ends of the calipers. We ground a bit off the edges of each caliper, but in the end still needed at least 1/4-inch wheel spacers to keep these wheels from contacting the calipers. Vehicles with wider or larger wheels may have less of an inference issue, or no issue at all.
With the axle work complete, it was time to address the master cylinder swap. Here you can see the new aluminum master. The adjustable pushrod is provided with extra length so it can be trimmed to the proper length. We cut it to closely match the dimension of the old one.
The pushrod eye on the stock master cylinder was smaller than the new one. We machined a steel bushing to press-fit into the new eye and provide the proper diameter to mate with the brake pedal.
We clamped the new master cylinder in a vise and used the provided bench bleed kit to run some fresh Red Line synthetic brake fluid through it to purge all air from the fluid passages.
The new master cylinder was bolted to the firewall and connected to the brake pedal. With the fluid lines reattached, the brake system was bled, completing the brake upgrade.

Sources

Summit Racing
800-230-3030
www.summitracing.com
Red Line Synthetic Oil
Benicia, CA 94510
707-745-6100
http://www.redlineoil.com

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