Search and found a 2006 LR3 90k miles with rear locking diff.... That rear locking diff is not easy to find but I wanted it. First thing was had all fluids changed including front and rear diff + tranfer, trans, and oil. My thought was to drive over semi mild hills rutted sand on my property a couple times a week to engage the lockers in hopes this will keep the in better working condition vs lack of use.... And a bit fun.

Initially found rear diff rarely locked in Sand and Mud Rut but sometimes in Rock Craw even when needed. Now, rear diff engages more often and sooner in all three modes mentioned. However, if front and rear is locked and the LR3 climbing sand hill looses traction, I reverse to descend hill a bit and the rear diff unlocks. When the rear diff unlocks, it make a Pop or Clunk sound due to pressure on it when it disengages. That can't be good!
Questions:
1. Is this 'Cluck' normal? Is the a way to change gears or settings while driving to prevent the 'Cluck'
2. why does the rear diff unlock when put in reverse? I don't think the rear diff has ever locked in reverse. Is that normal? I wish the rear diff would just stay locked as it would help if your in a bad spot plus get you in a location where it would be free of stress and then no 'Pop' sound. BTW, when rear diff is unlocked when not in load, there is no 'Pop' sound.
3. is engaging the locking diffs weekly good?

Need your words of wisdom. I love this LR3 and want to keep it a long time.

 

It could be any number of things along the driveline including the brakes. If you want to be certain its the rear diff you can take it out of special programs while locked and under load. Therefore it should unlock and make the noise for verification. But the rear diff engages clutches to lock, its not like a specific pin drops into place to physically hard lock it. So its not normally noisy engaging/disengaging. If the rear diff is not the issue, look at the driveshaft, diff mount, etc. The center mount of the rear driveshafts can partially fail causing more shaft flex than normal.

The e-diff engages when needed. In certain programs its more sensitive jus like traction control. For example in sand mode there is more slip allowed than in rock crawl. The diff acts the same way making each program unique. But like traction control, once you left off the gas all the way it often disengages. This is why people need to learn how to properly operate these system. Keep constant pedal contact to keep the system active. Of course changes gears means you are not moving and therefore it may unlock. If needed, it will engage again. It will lock, if needed, when going in reverse.

There is not really need to lock/unlock the diffs as part of maintenance. For most people this would be pretty hard to even do. Fluid changes are more important. Also engaging low-range once a month or so is a good idea.

 

Great info.... And you are correct about learning to drive with systems correctly. I know this from doing it wrong, trail and error. I am getting better as I learn.

Is there anyway to keep all locked when doing from drive to reverse? That would, I think, solve the concern.

 

When you are in reverse, your rear locker is effectively a front locker. If there is steering input, the computer is going to disengage it because having your fwd-facing wheels locked in a turn is not a great idea. Mine unlocks in R consistently too, I would not worry about that.

The clunk sound: if you've ruled out other sources and it's for sure the diff, then it's from the clutch packs. I experienced this. I wound up replacing the diff and the locking actuator since the latter doesn't come with the diff. I think that was the culprit in fact because that out-going diff only had 18k miles on it but the actuator was original. I had the rear driveshaft changed too for the hell of it.

I don't know what the long term effects are of simply not fixing it. I couldn't live with the clunk since it's obviously non-normal. My LR3 is my baby and I'm gonna have it forever so I do stupid **** like that.

 

I love my LR3 too. Almost as much as I seaplane I bought for a while nearly 20 years ago

I get what your saying about rear locker become front in reverse and can unlock due to uneven wheel rotation during a turn. But my rear lock disengages the moment the reverse is used and does not come back on, even if experiencing traction loss at front that is locked.... Inspecting the rear diff, I see blue gasket sealant looking fairly new (the LR3 condition is nearly a 9 of 10... 90k miles). That blue makes me think something was done to it within the past 6 months. Also, I noted the mechanism that engages making a locking rear diff looks original.

I bought the LR# from NC from speaking with them and pics, then had it shipped to FL. Learn a lot since then... questions I should of ask. Will be making some calls Monday for more history. But so far, no regrets and happy I researched enough to know about that rear locking diff. Some say a rear locking diff does not really help, the computer or ECU will do it, but I rather have it. My jeeps in the past have be stuck with one wheel in front turning and one in rear... did not what that

Heading out now to check shaft, u joints, and yes.... reverse up a sand hill and note results... Let you know

Thanks

 

Tried everything to get rear to show lock in reverse and could not. Odd though.... Reversed nearly about a 60 degree dirt incline, front showed locked, rear showed unlocked, but that LR3 went up that dirt like it was on concrete.... implying the rear wheels where pulling.

It was tough to get the rear lock light to show RED LOCKED, but when it finally did, it was very consistent in Sand and Rock Crawl... Never in reverse though.

Checked as much as possible on drive shaft and all felt and look good.

I think the 'Pop' sound is the rear diff clutch plates releasing when put in reverse and not the motor engaging lock rear diff. I also think the motor engaging rear locking may weak or failing. As soon as it's ask 4 or 5 times to engage, the rear locker engages as soon as it is put in drive, off as he shift t reverse, on back t drive. The rear diff even stayed locked at times the front diff auto unlocked driving straight. The front and rear showed locked while turning sharp on side of sand hill pulling well..

Any thoughts? Worries?

 

There is no way to practically override the programed behavior. And I agree with hour_wa, fix it dont ignore it. You need to be certain of the noise. It could even just be loose upper control arms (I have this my truck right now). As for steering and such when in reverse, that makes no sense at all. Its no different when driving forward into a turn, the rear end arch will be identical. With that said extreme wheel turn will disengage the rear locker whether in forward or reverse, but direction of travel is irrelevant.

If you can, get someone to go with you and see if they can help pin point the noise a little better from outside the vehicle. Just keep ruling out things until you can make a better conclusion.

On a side note, did they put in the proper rear diff fluid? Castrol BOT 720 is the latest one can get. There is also a GM fluid. Otherwise you have to go LR brand. The fluid is specific to carbon clutches, you can not use regular limited slip stuff.

 

Still need to take it out of all programs while in load.... back later

 

Yes I do believe they got the fluid correct. I spoke to the mechanic and he knew immediately the correct mix for the electronic locking diff. But I can't be sure. And there seems to be some debate about correct current fluid... Amsoil products kept coming up. I know Amsoil was used in the engine.

 

As long as it carbon clutch compatible, that's all that matters. The correct stuff is rather hard to find outside of the dealer. I was lucky to pick up a bunch from eBay for $26/quart (BOT 720). But after my next change, I am out.