Main goal of this post. Looking for ways to diagnose and test driveline failure. Differentials, transfer box, drive shafts, CVs. Planning on servicing diff and transfer box fluids. But other than that, what I can I do, or look for to track down the culprit? 06 LR3 with 193k on the clock.

Recently went from 19” wheels with 255/55/19 street tires to 18” 275/65/18 all-terrain tires. Went out for some fairly basic trail play this weekend, and noticed some clunking coming from the driveline when the car is navigating slow speed turns. Ended up turning around and parking the vehicle for the remainder of the weekend. We did some basic troubleshooting and observation once we got back to camp. When the car is in motion, forward or backwards at slow speeds, both high and low range, a sizable clunking can be heard, and the rear wheels are skipping. I was out of town, at a friends cabin, so needed to figure out a way to get home safely.

I have an IID tool, and no noticeable faults are popping up. I performed a self test on the rear locker, which seemed to be successful, I think. We unplugged the battery for a half hour to reset some things. After reconnecting the battery, we performed some moving tests again, and the results were much better. With the wheels turned, forward and backward moment, at first, it seemed like the clunking was completely gone. At least the large clunking had disappeared. There seemed to still be some smaller, more frequent clunking that started after some continued movement back and forth, with the wheels turned both directions.

I determined that it seemed like the car was good enough to get me home. No noticeable noises or clunking the entire way home. Seemed fine at highway speeds, and also navigating turns through intersections. Once I got home, and started to reverse into my driveway, the hard clunking returned once the wheels were turned. After a little bit of reading, I saw some folks talking about running a calibration on transfer case as a potential fix for this issue. I performed the calibration last night, my drive into to work the following morning seemed to be uneventful. Driving in my parking lot at the office involves a fairly sharp turn, and no clunking noticeable.

On my way to lunch, making a right hand turn forward, I heard some small clunking. Seemed to be because there was more load on the driveline to pull out from that turn. The more turns I took, the more I noticed the clunking happening again. It only happens if I’m accelerating while turning. If I’m coasting while turning, everything is fine. It’s not the big hard clunks right now, we’re back to the smaller, more frequent clunks.

 

Are you certain its driveline and not a control arm issue?

 

I'm honestly not certain of anything at this point. I think it's driveline, because I believe it increases frequency with road speed. And when I say road speed, I mean from 0-2mph.

 

If it isn't something in the rear driveshaft like the carrier bearing, then I'd bet on it being the clutch packs in the rear diff. I went through that, myself. There weren't hard faults, just the clunking and once in a while I'd see something about "clutch position not learnt." I don't remember the full syntax. IF that is it, you may be able to R&R the locking motor and re-calibrate, but it may need more than that; like a rear diff.

 

what do you mean by R&R the motor? How is recalibration performed on the rear diff?

 

Remove & Replace. The actuator for the locker is a separate, bolt-on part. I believe the calibration can be done by the IIDTool.

 

I’ll do some searching on this. Curious what others experience when the actuator fails?

 

Just throwing this attached PDF into the mix. I strongly recommend the software update even if getting to fault/code. The actuator replacement apparently requires calibration but one eBay or Amazon seller seems to sell one that skits that issue - not sure how but feedback seems to confirm.

I had a thread on a clunk issues, for me it was my rear upper arms that cause the issue.

 

Additional note. Sunday night, I retrieved a code from the transfer case. P2789-00 (2C) Clutch adaptive learning at it's limit.

One more thought. When I did the wheel upgrade, I swapped my 19's for 18's. I shop I worked with on this trade didn't have all 4 same tires on the wheels they traded me. They put the mismatching wheels on, with larger tires on the rear than compared to the front. I raised a number of concerns about the different sizes, but was encouraged it would be fine. I made it around the first turn, and DSC and TC were going crazy. Was on a one way street, so I needed to go around the block to get back to the shop. I requested that my old wheels be put back on, and I would return the 19s at a later time. How much damage do we think the trip around the block with 30" and 32" tires mounted caused?

 

I doubt there would have been any damage. The transfer case itself is also a differential. So really it would not be much different then spinning in the mud with the transfer case unlocked and the front/rears moving at different speeds. The code however is interesting, but I have nothing to add on that as I have never seen it before.