Converting CJ to Disk Brakes

So, an update. I put the '79 housing up on stands this AM and all the '84 brake bits bolted right up. Next trick is to pull the '76 6 bolt hubs, press pout the studs & try & mount the '84 (7/8") rotors to the backside of them. Per every measurement I took this should work, and the parts books say everything should mix & match....weird!

Fun pasr was popping off the old knuckles from the '79 housing. A buddy loaned nme the special socket needed to release the upper ball joint studs. To my astonishment a few good hammer whacks and all four ball joint studs came out clean as a whistle, as did the tie rod ends. No heating, cursing, pounding, etc. Somewhere along the line this is going to go south, but so far, so good.

Decades ago now, my brother converted his `76 CJ to disk fronts. As I recall it was a bolt-up job, no need to even change the knuckles. Pull the backing plates and bolt away. Jeep didn't change many things unless they were forced to.

But if your existing wheels are the originals they will not not fit your new brakes. The disk calipers will not clear by *just* enough to bind on the drum brake wheels.

Thanks, Lee. What I looked for was the 77-78 GM-style 6 bolt caliper supports, which makes the whole deal a bolt-on. Having struck out every time I thought I'd found a set, and not wanting to buy new ones, a buddy finally gave me a 79 housing & knuckles, which use the two-bolt style supports. He also gave me the 5-bolt hubs, disks, calipers, spindles & all the assorted bits from an 84 CJ7. So9 far everything looks like it will work, but I'm puching my luck (naturally) by trying to reuse the 6 bolt hubs off the 76, since I have a brand new sert of Warn premium hubs on 'em. Tomorrow's the big test, watch this space! :-)

Update: so far, so good. Got the '79 knuckles on with nary a snag, and after a mondo clean-up session got the '79 axle shafts & dust shields & '84 spindles mounted. The '79 splash shields had to be trimmed to clear the caliper supports, no biggie.

Anyway, my big gamble was that the '78-later 7/8" disks could be mounted to the back of the '76 6 bolt hubs, per all the parts catalogs...WRONG! Turns out mine's an early, early '76 and at that stage they weren't machining off the back side of the hub. Not to worry, a quick trip to the machine shop and we're in business with the rotors matched to the 6 bolt hubs. Tomorrow they get new bearing races and go off to be surfaced a bit.

Next adventure, installing the rotors, calipers & new brake lines, plus trying a trick that allows using the drum/drum master with front disks. News at ten!

It would be hard to steer his Jeep after that. He is doing the front disc conversion. ;-)

Chris

Uhhh, no, that would be the wr>>Update: so far, so good. Got the '79 knuckles on with nary a snag, and >>after

Update to the updates:

VOILA! It works!

Got the rotors faced off & installed, then buttoned up the new loaded calipers, new front lines and got the 6 bolt hubs reinstalled. Every step during this swap I was sure this Frankenstein of an idea I had was going to come to a screeching halt due to something I'd overlooked. Anyway, the last bit was to see if the '76 drum/drum master cyl. had even a remote chance of working, before I ran off to the parts store for an '82-86 non-power master. I've read a lot of conflicting articles on this. Some say that, like all drum systems, it has residual pressure valves front & rear that will cause front disks to drag, while other articles say it will work just fine. One online article said to pull the front line seat in the master with a sheet metal screw, remove the little check valve & replace the seat.

A bit more reading and to the rescue came the Jeep Bible by Willie Worthy, which correctly states that post-76 CJ masters do not have residual pressure (check) valves front or rear. One other odd thing I learned, post '76 Jeep masters have the primary chamber in front, rather than in the rear of the master. Go figure. Well, with everything buttoned up and with nothing to lose, I pressure bled the system and ..... hot damn, IT WORKS!!!!! Even better, without any adjustment the toe is spot on the money and the steering wheel is perfectly centered. (Think I should have played the lottery this week!)