Transfer case failure

[nj swb]

For those who haven't been following an obscure thread in "Forum Meets / Where to Go!", the following information was originally posted here.

As this event may be of interest to a much wider audience, I thought I should re-post it in this forum, and leave the trip thread for discussion of the good times that were had.

On the weekend, my transfer case overheated, and auto-installed a custom breather.



Well, that's one possible explanation...

Attempting to climb a steep, deep, damp sand track without using masses of momentum - those who had conquered it before me had left it a bit cut up, as I had left it for them after previous failed attempts.

Front & rear lockers in, low range, run up the hill until the car stops & cut the power before it digs in. I was entertaining myself (but probably not those watching) trying to work out if I was getting a little further each time, as I've had some success using a similar technique in other places.

On about the 10th run, something went bang and made a horrible noise. Spectators heard it clearly too. I had to turn the engine off to stop the noise - neutral on the trans wasn't enough.

After a few seconds, I started the engine again & all was quiet. I started backing down the hill, and immediately could smell gearbox oil - it's a rather distinctive smell. About half way down I looked back where I had stopped, and could see something dark on the track - not a good feeling.

At the bottom of the hill it wasn't hard to spot the oil draining into the sand from under the centre of the vehicle. My immediate thought? Catch the oil to avoid environmental contamination... Somebody entertained me & found a plastic bag to catch what was left. Was that geopaj? Whoever it was, thanks.

Somebody also identified that the front right CV joint was shattered.

The whole group came together to help, for which I don't think I thanked them all enough. m_and_m was quick to volunteer to tow me back to the campground, and letsgoplaces offered to take me on a reconnoitre trip to find an easy tow route back. We very quickly met Richo, a member of our host Holden 4wd Club, coming the other way with similar thoughts in mind, so we went back to my Paj & waited for guidance.

It still drives - in high range. Obviously, without oil in the transfer, I wasn't keen to drive it too much, but I had to put it in gear & drive some of the trickier twists & turns on the way back. Later, I had to drive it on & off a tow truck, but that's a minor side story.

Back at the campsite, others offered heartfelt condolences that were much appreciated. A few also made some phone calls for some advice, which is also much appreciated. I decided that, since my driving was over for the weekend, it was time to open a bottle (or three?) of red. Some joined me in drinking the red - again, much appreciated.

Seriously, the help and support I received was awesome. Thank you all.

The next day, after a few phone calls back & forward (talking to sootyNT, amongst others) it was all organised. After a leisurely pack-up, m_and_m again agreed to tow me out to the road. Where he crawled underneath, and took some more photos.




It was delivered to a Mitsubishi dealer this afternoon, and I'm waiting for a phone call. I have 4 questions:

1. What happened?
2. Why did it happen?
3. How do I know it won't happen again?
4. How much will it cost to fix it?

I've already rung Wholesale Automatics, to find out if they have any crawler sets left. No. If anybody knows of a set, please let me know.

When I spoke to the Mitsubishi service department, I asked if they knew if the transfer from the new Triton (with a 2.56:1 low range) will fit. They had previously wondered about that, and said they would do some more research - which will be nice if they do.

Having had a closer look at the bits & pieces collected from the sand (by others - thank you) it's clear that a number of teeth have failed - but why? Something like this has happened before, in Queensland about 11 years ago. I was there when it happened, and at the club meeting when the vehicle owner explained that it was all repaired under warranty - for him. I'm not the original owner of this Pajero, and the vehicle was first sold late '09, so I don't believe I'm covered.

I've been wondering if it was simply too much load, but I don't think that would explain the chipped & broken teeth - and too much load typically kills CV joints, not Pajero transfer cases. Failing teeth and/or jumping gears could (conceivably) produce a shock load through the drive train and shatter a hard-working CV, so I'm (now) comfortable that the failure of the transfer killed the CV, and not the other way around.

So I'm waiting for a phone call from Mitsubishi. I'll post the results.

[Alex86]

OUCH!!!!

Without seeing the broken off piece, my only thought is that maybe for some reason the teeth were mashing against it at some point weakening the case, and it fractured and split from there?

I'm not sold on that idea. The next I have is torque. But still, crikey what you've done is epic!

[bacon]

Should have brought a JEEP

[nj swb]

Should have brought a JEEP

I know! It would've caught fire, and this would be an insurance claim.

[MTN-KAT]

For those who haven't been following an obscure thread in "Forum Meets / Where to Go!", the following information was originally posted here.

As this event may be of interest to a much wider audience, I thought I should re-post it in this forum, and leave the trip thread for discussion of the good times that were had.

On the weekend, my transfer case overheated, and auto-installed a custom breather.



Well, that's one possible explanation...

Attempting to climb a steep, deep, damp sand track without using masses of momentum - those who had conquered it before me had left it a bit cut up, as I had left it for them after previous failed attempts.

Front & rear lockers in, low range, run up the hill until the car stops & cut the power before it digs in. I was entertaining myself (but probably not those watching) trying to work out if I was getting a little further each time, as I've had some success using a similar technique in other places.

On about the 10th run, something went bang and made a horrible noise. Spectators heard it clearly too. I had to turn the engine off to stop the noise - neutral on the trans wasn't enough.

After a few seconds, I started the engine again & all was quiet. I started backing down the hill, and immediately could smell gearbox oil - it's a rather distinctive smell. About half way down I looked back where I had stopped, and could see something dark on the track - not a good feeling.

At the bottom of the hill it wasn't hard to spot the oil draining into the sand from under the centre of the vehicle. My immediate thought? Catch the oil to avoid environmental contamination... Somebody entertained me & found a plastic bag to catch what was left. Was that geopaj? Whoever it was, thanks.

Somebody also identified that the front right CV joint was shattered.

The whole group came together to help, for which I don't think I thanked them all enough. m_and_m was quick to volunteer to tow me back to the campground, and letsgoplaces offered to take me on a reconnoitre trip to find an easy tow route back. We very quickly met Richo, a member of our host Holden 4wd Club, coming the other way with similar thoughts in mind, so we went back to my Paj & waited for guidance.

It still drives - in high range. Obviously, without oil in the transfer, I wasn't keen to drive it too much, but I had to put it in gear & drive some of the trickier twists & turns on the way back. Later, I had to drive it on & off a tow truck, but that's a minor side story.

Back at the campsite, others offered heartfelt condolences that were much appreciated. A few also made some phone calls for some advice, which is also much appreciated. I decided that, since my driving was over for the weekend, it was time to open a bottle (or three?) of red. Some joined me in drinking the red - again, much appreciated.

Seriously, the help and support I received was awesome. Thank you all.

The next day, after a few phone calls back & forward (talking to sootyNT, amongst others) it was all organised. After a leisurely pack-up, m_and_m again agreed to tow me out to the road. Where he crawled underneath, and took some more photos.




It was delivered to a Mitsubishi dealer this afternoon, and I'm waiting for a phone call. I have 4 questions:

1. What happened?
2. Why did it happen?
3. How do I know it won't happen again?
4. How much will it cost to fix it?

I've already rung Wholesale Automatics, to find out if they have any crawler sets left. No. If anybody knows of a set, please let me know.

When I spoke to the Mitsubishi service department, I asked if they knew if the transfer from the new Triton (with a 2.56:1 low range) will fit. They had previously wondered about that, and said they would do some more research - which will be nice if they do.

Having had a closer look at the bits & pieces collected from the sand (by others - thank you) it's clear that a number of teeth have failed - but why? Something like this has happened before, in Queensland about 11 years ago. I was there when it happened, and at the club meeting when the vehicle owner explained that it was all repaired under warranty - for him. I'm not the original owner of this Pajero, and the vehicle was first sold late '09, so I don't believe I'm covered.

I've been wondering if it was simply too much load, but I don't think that would explain the chipped & broken teeth - and too much load typically kills CV joints, not Pajero transfer cases. Failing teeth and/or jumping gears could (conceivably) produce a shock load through the drive train and shatter a hard-working CV, so I'm (now) comfortable that the failure of the transfer killed the CV, and not the other way around.

So I'm waiting for a phone call from Mitsubishi. I'll post the results.

WOW! The top photo looks like the gear climbed out of the mating gear it meshes with hence the mashed edge to the teeth. The alloy casing in which the bearing is housed could not hold the flexing shaft under extreme load and so it broke, "literally" in two and spat the broken half thru the outer casing presenting an unimpeded view of the site of destruction. Would appear the lockers overpowered the transfer gears and the weakest link, the alloy housing holding in the large bearing on a flexing shaft went bang. Just like you described.

[sub888]

Sorry to hear Scott. Looks expensive.
I know you usually only use your paj for trips away. Have you driven it since Saunders gorge? Is it possible you gave the transfer a belt there on rocks, put a hairline fracture in the casing, then when it became loaded its exploded?

[basil]

I have installed a few sets of low range gears and so have seen inside these cases many times when rebuilding them. They are not weak.
Initially my thoughts are that the housing has been weakened in the past by a hit from underneath or servere drive train wind up at some point. Possibly a bouncing of the front end with a lot of throttle. Most likely scenario.
There would have to be servere wear on the input shaft and main shaft bearings both cylindinrical/needle or counter gear bearings to allow any serious misalignment issues enough to cause the sort of side loading required to do this sort of damage and you would hear that.
Flexing of the input shaft, not likely.
Chain snapping or skipping on sprocket would lose drive to the front.

Mark 4x4 adapters may have some low range gears left on the shelf.

Transfer cases for these are cheap as there are so many about due to the low failure rate.

Cheers,

[Dicko1]

Would it be better(cheaper) to have a gearbox specialist look at it over the MM dealer?

[basil]

Call a few wreckers as I have seen them for 450 ish dollars.
Cheapest option I think.

[nj swb]

Update: Mitsubishi rang, and we had a good chat.

I specifically asked them about any signs of impact damage, and they say they looked and found none. So that appears to be excluded.

They proposed that under extreme load the CV let go, and a sudden acceleration / increase in drivetrain revs caused the failure of the teeth in the transfer. He then gave me pricing for repairs with new parts vs second hand. I listened to their explanation, then explained that I don't believe that's what happened.

Looking at this photo:


It appears to me that the bearing outer was spinning in the housing for some time, and some debris was sucked in to the gap. This debris then tracked across the bearing at an angle, suggesting to me that the bearing (at that stage) had been spinning while it wasn't square in its seat. The scar from the debris ended at a point where the case cracked.

In other photos, the bearing appears loose in its spot in the housing, suggesting that the housing had stretched before it shattered. I don't believe all of this would've happened in the immediate aftermath of a broken CV.

I believe [something ] inside the case failed, and created debris that ended up between the teeth, which are constantly meshed and have no space between them for debris. Metal into metal didn't go, so something had to give - which was the alloy housing. I suspect the ultimate TC failure event created a shock load in the drivetrain, which shattered the CV.

I also explained that I was present for a TC failure on an NP about 11 years ago, and a local Adelaide diff & gearbox specialist has seen two similar failures of Pajero transfer cases.

The Service Manager has taken this on board, and will strip the transfer case looking for evidence of another failure that may have started this chain of events. A representative from Mitsubishi SA was already scheduled for a visit tomorrow, so he'll have a look too.

I've also pointed out that the power train would still be under warranty if I was the original owner, and I've asked for Mitsubishi to help with cost of the repairs. The dealer will send the request up the line.

[Bogger]

Looking at your first pic a bit hard to tell but the broken edges look rounded as if the gears have been miss meshing for some time ? Or are they sharp ?
If broken edges are rounded / smoothed I'd say it's been waiting to happen ?

[nj swb]

Good question. It's a bit hard to tell from any of the photos if the edges are rounded or simply blurred - either slightly unfocussed, or noise from a low-light photograph (taken by m_and_m lying on his back under the car - I'm surprised there's this much detail visible).

But while I was having another look something else occurred to me. In all the photos I have the ends of the teeth that are further from the bearing are damaged. I can't see one tooth that isn't damaged at that end.

The other end of the same teeth are in much better condition. Of those visible in the following photos, only two appear to be damaged. If it was simply too much load, wouldn't the damage be more even across each tooth?

[my.paj]

To me it looks like there has been a lot of force on 2 gears for some time until the eventually drove them self away from each other

[stevemc181]

Not a good situation that's for sure! I hope you can get some assistance from Mitsubishi with the repairs, but I am thinking they will probably use the fact you have a front locker as a way out of any liability.

I think it will be hard to prove exactly what went wrong and caused the damage or whether the CV went before or after the Transfer Case. Hopefully they will show some sympathy and assist with the repairs. For what it's worth, I have seen some aftermarket CV shafts to suit the Gen 4 on Ebay. No idea what they are like though, but might save quite a few bucks over the original ones and cheapen the repair cost at least a little.

http://www.ebay.com.au/itm/1x-New-Genuine-GSP-CV-Drive-Shaft-for-MITSUBISHI-PAJERO-NS-NT-NW-M-T-A-T-RH-/171455616887

[GHendo]

Crikey mate, when you do a job on your vehicle you do a good one

It will be interesting to see what the final conclusion is as to why this happened - maybe you'll never know.

By the way, if you've got to get a replacement CV at your own expense, I'd get one from a wrecker if possible as the Mitsubishi CV's are much superior to the Chinese ones, by all reports.

Cheers

Geoff