2003 Rubicon lockers (and also a question)

danwink

danwink

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Good morning all!

My new to me Rubi (03, 72k miles) has been with me since Tuesday.

When I was looking at it, I verified the air lockers both were functional.

I was on the trail last night and engaged front and rear. Both locked up and worked normally for about 5 minutes then the light went out and they were unlocked.

I’ve dug around in the forums, I will pull the lines (carefully) and check for leaks.

As it is shutting down, I suspect the compressor may be overheating. Figured someone here may have had a similar experience.

I don’t mind fixing them, but don’t want to throw good money after a poor design. How much time/money is it worth throwing at them versus upgrading to ARB’s or some e-lockers?

The last thing I want is these being unreliable on tough trails.

Appreciate any perspective.
 
You need to do some troubleshooting. And that starts with knowing how it's supposed to work.

Why do you think the compressor(s) overheated? Did you hear them running and then stop?

Is the entire locker setup original as in the lockers, compressors, switches, ...?

Assuming it's all OEM, each locker is powered by a small compressor. In a quiet environment, you should be able to hear the compressors running. When you activate the switch to engage a locker, the compressor is turned on to pressurize the actuator. The compressor should only run for a few seconds until the system is pressurized and it should hold pressure while the locker is engaged. If the compressor runs continuously or almost continuously, you have a leak somewhere. A small leak causing the compressor to run occasionally isn't a concern. There is no way a compressor should overheat unless it's running a lot more than it should.

Assuming it's all OEM or equivalent, here's the expected locker behavior:
  • Must be in 4low and below a certain speed to engage lockers.
  • I believe if you exceed a certain speed, lockers will disengage. Is that possibly what happened?
  • Pressing the locker switch once, engages the rear locker and light on dash should illuminate.
  • Pressing the switch a 2nd time engages the front locker and should illuminate the dash light.
  • Additional presses will toggle the front locker on-off-on-off...
  • Lifting the locker switch will disengage both lockers.
To test the actual locker engagement, raise 1 wheel off the ground on each axle with trans in neutral and TC in 4low with key on. Then go through the different scenarios and test that they engage and disengage as expected by trying to rotate the raised wheels.
 
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FYI, my rig has roughly 130K on it and the front locker is original. The rear locker was good until an installer I hired most likely dropped the rear actuator while doing a re-gear. Not positive how it got damaged but the rear actuator suddenly had a leak where the mounting bracket was welded to the main assembly after the dude installed new gears. The bracket was clearly bent so I can't blame the locker for the failure.

That said, the Rubicon has both a locker and limited slip in the rear diff. That LSD is known to fail if worked hard at all and it destroys the locker when it goes. Keeping the rear locked when wheelspin is anticipated helps keep the OEM rear locker alive and well.

I wouldn't invest a ton of $$ into fixing the original lockers but you might have a simple fix to get things working. If 1 or both actuators are leaking, nobody makes replacements so used OEM or aftermarket lockers are your only options. Good used compressors should be easier to find since they only work with OEM lockers and many OEM locker are upgrade to something from the aftermarket.
 
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g.hayduke said:
FYI, my rig has roughly 130K on it and the front locker is original. The rear locker was good until an installer I hired most likely dropped the rear actuator while doing a re-gear. Not positive how it got damaged but the rear actuator suddenly had a leak where the mounting bracket was welded to the main assembly after the dude installed new gears. The bracket was clearly bent so I can't blame the locker for the failure.

That said, the Rubicon has both a locker and limited slip in the rear diff. That LSD is known to fail if worked hard at all and it destroys the locker when it goes. Keeping the rear locked when wheelspin is anticipated helps keep the OEM rear locker alive and well.

I wouldn't invest a ton of $$ into fixing the original lockers but you might have a simple fix to get things working. If 1 or both actuators are leaking, nobody makes replacements so used OEM or aftermarket lockers are your only options. Good used compressors should be easier to find since they only work with OEM lockers and many OEM locker are upgrade to something from the aftermarket.
Click to expand...

So apparently I am losing my mind. I checked both pumps, inflating quickly and not cycling.

I then went over to a trail, hit 4L and engaged both. Confirmed they lock and went on a 10 minute drive. Practiced locking and unlocking the front. No problems, they worked perfectly.

Maybe I accidentally toggled them off this weekend and tried to engage them above 10 mph.

Thanks for the tips above.
 
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danwink said:
So apparently I am losing my mind. I checked both pumps, inflating quickly and not cycling.

I then went over to a trail, hit 4L and engaged both. Confirmed they lock and went on a 10 minute drive. Practiced locking and unlocking the front. No problems, they worked perfectly.

Maybe I accidentally toggled them off this weekend and tried to engage them above 10 mph.

Thanks for the tips above.
Click to expand...

Or could they have unlocked automatically because you exceeded the maximum speed? I forget what the max speed is but it's not fast and they will auto-unlock if you go too fast.
 
Maybe, I tried to go fast but it is pretty hard with 4.88's in low. It could have been on a downhill as I was going down last time. Thanks again for your help!
 
danwink said:
Maybe, I tried to go fast but it is pretty hard with 4.88's in low. It could have been on a downhill as I was going down last time. Thanks again for your help!
Click to expand...

My top speed in 4L is 20 mph in 5th gear. :unsure: I read they won't engage above 10 mph and will disengage at 45 mph. I've never tested either.
 
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I was just reading the sticky on how to activate lockers in 4H or 2wd. It indicates that 45 is the speed that it automatically disengages. An impossibility for me (and you).
 
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TheBoogieman said:
My top speed in 4L is 20 mph in 5th gear. :unsure: I read they won't engage above 10 mph and will disengage at 45 mph. I've never tested either.
Click to expand...

I'm curious where you found the 45 MPH top speed. I couldn't find that nugget myself.

My rig no longer has the OEM locker setup but I'm pretty sure it auto-unlocked on me more than once when going faster than it allowed in locked mode. I can't test it since I changed the wiring. So I can't verify it but I really thought that was a thing with the Rubi lockers.

And while 45 is beyond top speed in 6th in 4Lo, it's totally obtainable downhill in neutral :)
 
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Okay- I’m back. Did some more wheeling yesterday.

So, they will lock up fine and work well…. until they don’t. They turn themselves off after a while and won’t reengage unless I turn the jeep off.
 
danwink said:
Okay- I’m back. Did some more wheeling yesterday.

So, they will lock up fine and work well…. until they don’t. They turn themselves off after a while and won’t reengage unless I turn the jeep off.
Click to expand...

Maybe it's losing a safety input.
For example, a flaky 4-low switch.
 
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