4 Low unlocked

[nj swb]

So twisted32 very graciously developed a problem in his NW to take my mind of the problem I have in my NT - no centre diff lock.

I can still get low range, and all the lights are happy. It's not an electrical problem. The way my Gen 4 box is designed, if the actuator selects low range is has also locked the centre diff.

But on steep climbs I realised something was wrong, and have recognised a number of new situations:
1. Traction control was working much harder than I was accustomed, on tracks I had driven before (and others in the group with similarly equipped Gen 4s were experiencing much less intervention).
2. With rear ARB locker selected, traction control was still working hard, and cutting out on me - unheard of on the climbs we were on, and others weren't having the same problem (no, not a tyre issue - good tyres, lower than anybody else).
3. Watching the traction control lights, I was regularly getting one front (lightly loaded) light flashing at a time. With centre diff locked, a wheel needs to spin on each axle - it's not unusual to occasionally have TC flash only one light, but not as often as I was having.
4. On steep descents, as wheels lifted and the vehicle tried to run away, the brake intervention (whatever it's called) would activate, and flash one rear (lightly loaded) light at a time - again, with centre diff locked, it should detect issues with one front and one rear.
5. Back at camp, where I would normally need to revert to 4H for reversing my Paj into where I normally park (position the rear door under one edge of my gazebo) it was quite happy to do so in 4LLc.
6. I spent some time doing low speed circles in different modes, and could detect no difference in full-lock circles in any of the 4wd modes.

So, I'm convinced my centre diff isn't locking, but I also have no doubt that low range is working.

What's happened?

[twisted32]

What's happened?

You have been having too much fun for the past year, and the transfer police say "no"

[Pickle]

You have been having too much fun for the past year, and the transfer police say "no"

Ha ha More like as soon as you cross the border
Dave

[nj swb]

You have been having too much fun for the past year, and the transfer police say "no"

Ha ha More like as soon as you cross the border
Dave

So it will all return to normal once I get home?

[twisted32]

So it will all return to normal once I get home?

Yes, because you won't be using the centre diff lock as a Toorak tractor....

[Alben]

Haven't gen 3 and 4 paj owners wanted this as an option for ages? When you find what's going on you might be able to sell the secret to others for easier reversing trailers uphill etc.

[NJV6]

Given the centre diff is locked when in 2H, how does it behave in this mode?

[geopaj]

I’m getting increasingly worried about the strength of these gen 4 transfer cases!

Have you had a chance to check the oil?

I’m wondering if its physically destroyed the centre diff lock mechanism/splines?

Between you and Twisted32, it sounds like a trip of carnage! Not good

[old Jack]

The saying used to be "play hard or go home" maybe it should be "play too hard and you won't get home".

Over diameter tyres, diff locks and power enhancements all put extra load on the "mechanical fuse" that is between the engine and driveline, in a manual transmission it is the clutch and in an automatic it is the torque converter. Travel heavy and or play hard and the nearer you are to "blowing the fuse", at some stage you will go over the limit and something will break.

Walking the fine line between recreational and "wreak-reational" is something many of us do regularly that go offroad, sometimes the line gets crossed and we get away with it and other times we do not.

OJ.

[nj swb]

Given the centre diff is locked when in 2H, how does it behave in this mode?

Good question - I don't know.

For some time now I haven't been using 2H because I had flashing front wheel lights, and I could hear the transfer shift mechanism "hunting" - presumably for the switch indicating 2H. 4H worked fine, so I was lazy and didn't attempt to fix it.

Until I recognised that I had this problem, I had no issues changing between the 4wd modes, but on this trip (after I realised my centre diff isn't locking) I began to have trouble - the actuator would drive, but then all the green lights would go off and the centre diff light flash. With a bit of mucking around I can select any mode I choose, and the dash lights work as they should for that mode - except the flashing front lights in 2H mentioned above.

Off road, I can still access 4L, and I can still lock my front & rear diffs - in the immortal words of Meatloaf, two out of three ain't bad.

[Just Cruzin]

Easy fix, get a gen 2 (that goes) with manual front hubs and just ignore the flashing xmas tree lights.

[NJV6]

Over diameter tyres, diff locks and power enhancements all put extra load on the "mechanical fuse" that is between the engine and driveline, in a manual transmission it is the clutch and in an automatic it is the torque converter. Travel heavy and or play hard and the nearer you are to "blowing the fuse", at some stage you will go over the limit and something will break.

OJ.

I guess the disappointing thing about all this is that the gen2’s would take 33’s and even 35’s with very little issue, they seem better in front cv’s and especially transfer cases.

[old Jack]

I guess the disappointing thing about all this is that the gen2’s would take 33’s and even 35’s with very little issue, they seem better in front cv’s and especially transfer cases.

Gen 2's engines where producing less power and torque and diff ratios also where much lower so less loads on the drive line relative to the size of the internal mechanical components. This is not just a Mitsubishi issue all manufacturers have similar issues as they continue to use the same mechanical components but fit more powerful engines and strive for improved fuel economy and greater payloads.

OJ.

[ticky]

Sorry to hear of your troubles mate. Its hard to find a good side of the story but if there is one, i think it would be that you and Twisted, along with Razorback, will work out what caused the issues and no doubt over come them. Yell out if you need any tools or if I can help in anyway.

Steve

[nj swb]

So the fun has continued.

Yesterday the transfer case was stripped, and there was nowhere near as much carnage as I had been expecting.

My guess of the 2wd / 4wd selector fork having broken loose from its rail was incorrect - it's all intact, and appears to be working as normal.

The aftermarket reduction gears are unharmed - they're in perfect condition, and can be transferred to a new transfer case if required.

There are no signs of damage to the centre diff, or the drive chain and sprockets that transfer drive to the front output shaft. No evidence of damage to any of the bearings, such as that discovered by geopaj. The speed sensors look fine.

The 2wd / 4wd shift rail was jammed - it would not move in either direction. On disassembly, it was discovered that a brass synchro ring was damaged - the locating features that keep it in the correct spot have been stripped, allowing the ring to rotate out of its correct place, and prevent proper engagement.

So how did that happen?

Last year, towards the end of a day trip to Jakem Farm, my NT was unable to climb one of the hills. In 4LLc, it would only climb a little way, then effectively became gutless - couldn't climb any further, and there was an unusual clicking / knocking noise that was hard to describe. From outside the vehicle, twisted32 observed that he could see the rear wheels "loading up", but the front wheels didn't appear to be doing anything. I cycled the transfer case back to 2H, then came forward to 4LLc again, and it flew up the hill - no dramas at all.

While the transfer case was in pieces yesterday we spent some time playing with the positions of the gears between the main shift rail and the secondary shift rails (2wd / 4wd, and High / Low). We did find a combination of rail and gear positions that produced 2wd low, with partial engagement within the 2wd / 4wd selection hub - this could explain what happened at Jakem, but we still haven't managed to prove this is what happened.

If this is what's happened (that's a big "if"), how did it happen?

The following is speculation - I need a new synchro assembly to do further testing.

Installation of the after-market low range gears requires removal of the Hi / Low selector fork on its rail. To get this rail out also requires removal of the intermediate gear, and it's possible that the other gear, driving the 2wd / 4wd rail, had been removed too. If those gears weren't put back in exactly the correct spot, that could possibly have been the root cause of subsequent events:

1. I selected 4LLc, and the electric actuator detected the correct combination of switches without the selector hub being in precisely the right spot.

2. High load in the selector hub ("downstream" from the 3.15 low range gears, seeing more load that it would with factory reduction gears) may have created the initial damage to the synchro ring, while the rear wheels were driving but the front weren't, and something sounded like it was "slipping", or "jumping" somewhere.

3. After cycling the transfer case back to 2H and then forward to 4LLc, the actuator then managed to drive everything to where it belonged, and the vehicle performed as expected. But damage had been done.

4. Some time later, on another trip (Warraweena, Saunders Gorge, the Simpson, Peake, Loveday all saw 4LLc use) further damage was done, until one day the hub jammed - and it wasn't until I hit the High Country that I realised something was wrong.

So what does all this mean?

Well, it's still speculation - nothing has been proved. But I don't see this as a serious weakness of the Gen 4 transfer case - it's quite possible that this failure has been caused by pulling it apart, and putting it back together incorrectly. Yes, this suggests lack of robustness of the inherent design, allowing indicators to indicate that all was right when it wasn't, but there also exist many opportunities to assemble an engine incorrectly, which would cause far more trouble than this. With this failure I was able to continue 4wding in the High Country (thanks to front & rear Air Lockers), drive home to Adelaide, and continue to use it as a daily driver until the transfer case was swapped out.

So, next step is new synchro assembly, and more testing. Stay tuned.