Editor's Note:
Some modifications never become outdated, especially those that are simple bolt-on improvements that can be done with junkyard parts. We still get questions about swaps and conversions we did it over five years ago. This is one of them. And it's the first installment of our new Timeless Tech series.
Early Jeeps with closed-knuckle Dana 25, 27, and 44 front axles are not known for speedy deceleration. In fact, stopping in a hurry with the 9-inch drums can cause a religious experience-or at least the utterance of a few sacred words used in vain. So what is to be done? You could find a narrow-track Dana 30 complete with disc brakes from a later CJ, but that can become quite expensive if the axle needs to be refurbished before installation. So why not put some discs on your early axles using common easy-to-get parts? Here's how it works.
What you need:
* Calipers from a '71-'78 Chevy 1/2-ton or light-duty 3/4-ton 4x4 with a Dana 44* Caliper mounting brackets from a '73-'91 1/2-ton Chevy 4x4* Rotors from a '77-'78 CJ. These rotors are 1 1/8-inch thick* Ten longer wheel studs (we used Dorman PN 610106)* Chevy 1/2-ton brake lines (Pro Comp PN 7220)* A grinder* Standard handtools* Brake fluid, new hard brake line, banjo bolts, and a bleeder kit
1)First, you need to collect the rotors, caliper mounting brackets, and calipers. You can either hit a junkyard to get all this stuff, or you can save yourself the headache and get all-new stuff at the parts store.
2)Start out by stripping off all of your old drum brake stuff. That's right-down to the spindle. Now that you have the hub and drum off, you should find someone who can press the old wheel studs out or you can bang them out with a hammer.
3)Next, place the rotor behind the hub and have the wheel studs pressed through the rotor and into the hub. If you don't put the rotor behind the hub, your brakes won't line up with the calipers.
4)Attach the spindle and Chevy Dana 44 caliper mounting brackets with a couple bolts to test for caliper figment. You will need to replace the 12 (six per side) original fine-thread backing plate bolts with ones that are 1-inch long. You could also step up to some studs at this point.
5)In order to provide clearance for the caliper, you will need to grind a little material off of the knuckle (arrows). With the caliper mounting bracket on the spindle, you can get an idea of how much grinding will be necessary to fit the caliper. Remember that as the pads wear out, the caliper will move inward because of its floating design. If you don't grind enough, your caliper may hit the knuckle and render your brakes useless. We ground the fill plug for clearance, although you could just replace the plug with a flush-mount one. Now you can start grinding the knuckle between the two bolts that are farthest to the back of the knuckle. You don't have to remove a ton of material, but make sure you have good clearance by periodically replacing the caliper mounting bracket and caliper for test fitting.
6)Also grind the caliper a little (arrow) to make sure that there will be no contact between it and the knuckle as the pads wear out, but be careful not to grind through the casting.
7)Once you have removed enough material, you can then begin rebuilding your front axle. Now would be a good time to replace those worn-out bearings and seals. Remember to pack the bearings and grease everything.
8)We decided to move the hard brake lines from the axle to the frame. We used a couple pieces of bendable brake line from our local parts store and a set of stainless steel brake lines from Explorer Pro Comp for a Chevy 1/2-ton. We used the metering block from the new Pro Comp rear brake line to split the front hard lines to both sides. Bleed the brakes, and you're on your way. Make sure to check the caliper clearance as the pads wear.
Stopping is as easy as "holy son of a ?*&@#!"
Prior to converting our Willys to disc brakes, we were fairly sure the huge number of descriptive expletives that we so often used when trying to bring the old Jeep to a stop would result in an eternity in hell spent working on electric-powered RAV4s and Honda CRVs. Now that the Willys has disc brakes, it stops so rapidly that the rear tires in the air cause more expletives to be uttered, and despite our hopes of redemption, all hope is lost. Hell, here we come.