Rubicon Front Locker Permanently Locked

DougVA

DougVA

New Member
Joined
Jan 23, 2020
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Virginia
Howdy,
I'm new here and new to TJ's. I used to mess with CJ's and decided to get back into the Jeep world with an '04 Rubicon. I've had it for about a month and noticed the passenger side front axle seal was leaking. So I tore into it yesterday and got it all back together today.
When I took it for a test drive, I noticed that the front axle is now locked. If I hit the locker button inside, the light on the dash just flashes. I've tried going from forward to reverse, but it won't unlock. Everything worked great before I did the seals.
I couldn't find any videos on reinstalling a center section that has the locker in it. All of the ones on YouTube for the Dana 30 & 44 seem to be for open diff's. Is there a trick to reinstalling a Rubicon center section? I plan to pull the cover back off and look for anything obvious. Any guidance would be greatly appreciated.
Thanks in advance!
 
Did you use the toothpick on a string trick to set the plunger sensor before putting the carrier back in?
 
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DougVA said:
Nope. I'm guessing I'll need to pull the carrier to set the plunger?
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Most likely. Get access to the plunger switch in the rear upper right corner of the housing. Cut a small stick to be long enough to hold the plunger in the extended position. Tie a string or thin wire around it. Set the plunger. Install the carrier. Pull the stick out. The locker should work after that.

Right now the plunger is almost certainly holding the locker in the locked position.

Also be sure that the drain plug isn't screwed in too far. That can also interfere with the locker.
 
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jjvw said:
Most likely. Get access to the plunger switch in the rear upper right corner of the housing. Cut a small stick to be long enough to hold the plunger in the extended position. Tie a string or thin wire around it. Set the plunger. Install the carrier. Pull the stick out. The locker should work after that.

Right now the plunger is almost certainly holding the locker in the locked position.

Also be sure that the drain plug isn't screwed in too far. That can also interfere with the locker.
Click to expand...

That's great information. I figured it must have been something related to the locker that I didn't do right. Thanks so much!!!
 
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I use masking tape. I take a piece about 24" long and place the toothpick in the middle, fold the tape on itself and trim the excess at the toothpick. It is much less tedious for fat fingers and aging eyesight.
 
That should do the trick indeed. Let us know if it ends up solving the issue.
 
You really need to avoid driving it ... typically if the sensor pin is behind the flange , it wont disengage completely, feel full locked , and can do some real damage .

If you have to drive it , its best to activate the locker so at least its full on ...the light will flash , as if it isnt .

Go easy.
 
Before you get too deep into make sure you didn't just overtighten the lube fill hole plug. If that plug is in there too tight that means it's in there deep enough to jam the locker up. Loosen the fill hole plug substantially and drive it around to see if it makes any difference.
 
Thanks for all the information. I tore it back down today and did the toothpick and string trick. When I put the carrier back in and pulled the string I heard the plunger snap back against what ever it rides against. I applied air to the actuator with a small compressor, and it does push the ring in. I also tightened the drain plug to 25lbs, which is what I saw online.
I put it back together and now the front locker light flashes all the time, and the front locker is still engaged. When I hit the lock button the light goes solid. I loved it around my gravel driveway outside the garage and its definitely locked.
So, it's back into the hog's head again. Hopefully third time will be a charm.
Here's a thought. The first time I pulled the carrier, I had to pry on the passenger side, and I took a strap and looped it around the carrier to get pressure on the other side. Of course it came all at once while I was standing up and dropped into a box with padding. The shim on the passenger side remained in its place next to the seal. The other shim fell out.
I've assumed that the shim that came out goes on the driver's side which is next to the locking mechanism. The ring and pinion seem to turn fine. Yet is it possible that both shims go on the passenger side and me putting on the driver's side is causing enough pressure to lock it? It differential locks even when there is no air on the actuator.
I'll be happy to get it fixed, the smell of gear lube is not my favorite :)
Thanks
 
Chances are good that there is only one shim per side. But it is incredibly important that they not be mixed up or you risk ruining the ring and pinon.
 
jjvw said:
Chances are good that there is only one shim per side. But it is incredibly important that they not be mixed up or you risk ruining the ring and pinon.
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Right....I've been keeping track of them even though they do mic the same thickness.
 
Jerry Bransford said:
Before you get too deep into make sure you didn't just overtighten the lube fill hole plug. If that plug is in there too tight that means it's in there deep enough to jam the locker up. Loosen the fill hole plug substantially and drive it around to see if it makes any difference.
Click to expand...
I think the over-tightening issue only applies to the rear locker, the front fill plug is located slightly higher which allows sufficient clearance between the locker and fill plug.
 
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mrblaine said:
Assuming that the cover hasn't been swapped.
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Good point, I never thought about a cover swap. Have you ever ran across an aftermarket cover that the plug will interfere with the locker operation? Up until my current Rubicon with an ARB rear diff cover I’ve only ever ran stock-ish covers on my Jeeps, usually front covers from early 2000’s Dodge 1/2 tons
 
DougVA said:
It's the stock dana cover. The Jeep has 107k miles, and I think I'm the first one into the front diff.
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Still, it wouldn't hurt to eyeball the relative height of the f/r fill plugs. The front should be noticeably lower than the rear (I'm betting that's what Vinman meant to say:)). If they had been inadvertantly swapped front and rear, the higher plug in the front could contact the locker. And just as bad or worse, the lower plug in the rear could eventually starve the axle bearings of lube.
 
Vinman said:
Good point, I never thought about a cover swap. Have you ever ran across an aftermarket cover that the plug will interfere with the locker operation? Up until my current Rubicon with an ARB rear diff cover I’ve only ever ran stock-ish covers on my Jeeps, usually front covers from early 2000’s Dodge 1/2 tons
Click to expand...
Back cover on front may do it. Lots of folks may not pay attention to plug location.
 
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