by Robert Landrum
In April of 2006, while wheeling in Moab, my front OX locker stopped functioning correctly. This is not the first time this has happened. It would frequently flake out, and stubbornly refuse to lock, even with the shifter in the locked position. I'd heard from several sources that there was a post on JeepsUnlimited.com that outlined how to convert from a cable actuated OX Locker, to an Air Cylinder actuated system.
Despite several searches, I was unable to turn up the post in question. A few months past, and the Jeep sat unused. Until about 2 months ago, when John Borg mentioned that I hadn't been wheeling for awhile, and I mentioned that the jeep was in a minor state of disrepair, casually mentioning my frustration with the OX. He managed to dig up the JU post that outlined the changes. I later received it from Wayne Lau as well.
The premise is simple. Remove the cable, install a small air powered actuator into the OX cover, and connect it to an air switch. The post contained part numbers, which I'll reproduce here, but lacked photos, which would have made my installation much easier.
Parts List
| Part | Quantity Per Axle | Source | P/N | Cost |
|---|---|---|---|---|
| Cylinder,Air,1 1/16 In | 1 | Grainger | 6W073 | $20.00 |
| Valve,Solenoid,1/8 In | 1 | Grainger | 6JJ52 | $27.90 |
| Brass Hose Barb,1/4 In | 5 | Grainger | 4A496 | $0.81 |
| Brass Hose Barb,1/4 In (90 degree) | 1 | Grainger | 4A491 | $3.50 |
| 1/4 In ID Rubber Air Host | 25 ft | Home Depot | -- | $20.00 |
| Host Clamps (Very Small) | 6 | Home Depot | -- | $0.75 |
| 14 Gauge Wire | 25 ft | Home Depot | -- | $9.00 |
| Toggle Switch | 1 | Radio Shack | -- | $2.99 |
| 12 Volt LED | 1 | 12voltguy.com | -- | $6.99 |
| Aluminum Crush Washer 3/4 ID | 5 | pegasusautoracing.com | 3278-08 | $6.49 |
The original JU post suggests using a Allen Cap Head screw, 2 inches long, 28 tpi, which was impossible to find in Warrenton. I bought mine from allensfasteners.com. As it turns out, I didn't need it for my install. It also mentioned using small copper crush washers between the air cylinder and the OX cover. I wasn't able to locate any of these in the sizes needed (larger than 5/8th inch inner diameter). I purchased some Aluminum ones online that were 3/4 inch ID, and those worked fine, but were rather thick.
I also used some crimp connectors, and thread tape, which I assume you already have if your tackling this sort of job. And of course, I also assume that you have some sort of on-booard-air system. Installation of such a system is well beyond the scope of this write up.
Once I had collected everything I'd need, I got started by laying everything out
Now I began by installing the air cylinder into the OX cover. I began with 3 crush washers, as this positioned the exhaust port of the air cylinder in the vertical position when fully tightened.
Unfortunately this pushed the fork away from the inner edge of the housing where it needs to rest.
It should be resting here.
I needed to cut off a few threads. This can be done with a hacksaw or a dremel. I used a big cut off wheel.
I rounded over the end with a file, just to clean off any burrs.
As you can see, the fork now rests against the inner wall. The throw on the air cylinder is 1 inch, which is more than it needs to engage the OX, so cutting of a little bit too much isn't a problem. I removed about 4 threads worth.
At this point, I threaded in the fittings. I didn't tighten down the air cylinder the final half turn needed until after the fittings were in, because the fittings interfere with the OX cover. You can see here that the 90 degree fitting is resting against the cover, and will prevent it from turning any further.
The next step is to install the cover onto the axle. Don't forget to use hose clamps. While the 1/4 inch ID tubing fits snugly over the fittings, 150 PSI is a lot of pressure.
The hose connected to the end of the air cylinder is the main supply line. The host connected to the other fitting is the exhaust port, and isn't connected to anything, but is needed to vent air as the cylinder moves. You could technically not run a hose, but then dirt, mud, and sand would make their way into the hole and ruin the air cylinder. I ran both lines up into the engine bay, following the axle vent tube.
I routed them around the air box and connected the exhaust line to the radiator support. I ran the main supply line over the radiator support to the passenger side, where I mounted the solenoid valve air switch.
I next connected the air cylinder supply line to the clearly marked "Out" port on the solenoid valve. I connected the "In" port to my main on-board-air supply. I connected a hose to the exhaust port, marked "Exh", and ran that up to the firewall. It's there just to keep dirt from fouling the solenoid, since it's only used to vent excess pressure from the air cylinder supply line when the solenoid is inactive. If it didn't do this, the OX would never disengage.
From here, I ran a wire inside to the toggle switch, and from the toggle switch to a LED light, then to ground. I connected the other wire to the positive terminal on the battery. When the switch is on, the LED light is on, and the OX is engaged.
How Does It Work
In my garage tests... Perfectly. The air cylinder is far more reliable than the cable. Every time I flip the switch, the OX engages. If I turn it off, it disengages. Things I could really only hope for when I used the cable and shifter.