NM Transfer case

[psproule]

Hi Folks, if any of you also hang out on the pajeroclub or overlander forums you may have followed the first part of my story with an NM centre diff lock that doesn’t lock:

http://www.pajeroclub.com.au/forum/foru ... =9876&PN=1 (fourm is down at the moment)
http://forums.overlander.com.au/viewtopic.php?t=38948

The short story is that under load it lets the diff lock go with a graunch and sends all the drive to the wheel with little / least traction. Mitsu have firmly claimed that this is normal behaviour. The have had this one apart before to fix a sticky actuator & shift rail. Anyway, I have given up fighting with Mitsu so this-morning we pulled the transmission out ready to drop it off to a trans specialist tomorrow. Once we had it on the ground we popped off the top cover to have a look at wether they had set up the shift rail properly last time they worked on it. Here is the manual. Have a look at page 115, item V here:

http://athene.csu.edu.au/~psproule/22C.pdf (3.6mb download)

The left hand gear in this one is in about 5 teeth anti-clockwise of where it should be from the picture! I'm guessing that is what is causing our problem. It's interesting though that all the sensors show that the diff-lock is going in properly. However the diagrams don’t state what position the actuator is in for the picture to be correct. I am assuming the default of 2H, which seems to be with the shaft all the way in?

The other thing that I can’t exactly work out without tearing the case down is how the diff lock engages. There is very little reference to it in the manual. On page 107, item 47 is listed as the diff lock hub, but I cant actually work out the mechanism by which it is locked. Is it by item 42 2-4WD clutch sleeve moving further back to grab it? If so how does that lock the viscous coupling out?

The dilemma now is wether to simply put the shift rail drive gears back in as they should be and put it back in the car, or to get the trans specialist (who has never had a late one of these apart) tear the case down to see if there has been any damage of gears due to the grinding noises on the occasions it has let go.

Has anyone else had one of these apart that can shed some light on the internals of NM/NP Super Select II?

Cheers & thanks - Pat.

[-Scott-]

Hi Pat

I'm sure you're already aware, but the "letting go" is NOT normal. Mitsubishi are lying to you.

I'd be looking to have a "qualified" specialist pull it down, inspect and report, with a view to taking the report to Mitsubishi and reaming them with it. Consider getting an auto club/MTA involved, to nominate somebody "qualified."

Good luck, and keep us informed.

Scott

[Bitsamissin]

Pat, from what you have said it sounds like the actuator is not engaging the centre difflock clutch sleeve properly. So when it's under load it's slipping causing the grinding noise. The question is has it done any damage by doing this ? Since you have it out I would open it up for an inspection. A competent gear mechanic will quickly see how it works.
It must be engaging enough for the centre diff detent switch to complete the circuit and hence light up your dash light.
The NM/NP's have a remote actuator system which I personally don't like with the older lever models there was no mistake which gear you were in.
The 12V remote actuator winds the selector rail in and out for the desired gear ratio. If the gear mechanism is out of sink then you will have major problems.
The centre diff and viscous coupling are an integral unit in both SS versions, SS1 uses a conventional spider gear centre diff, SS2 uses a planetary gear centre diff.
Both are locked in high or low range via a dog clutch sleeve.
I've had the SS1 & SS1.5 t/cases apart before (the SS1.5 is the larger one for the 3.5 V6) but I've never had a SS2 apart before. The internals work pretty much the same though except for the remote actuation.
My advice is to let your gear mate pull it apart to check for any damage especially the centre diff itself and the dog clutch sleeve. Once it is mechanically ok and reassembled then the actuator system has to be thoroughly checked for correct positioning.
Good luck with it all and let us know how you get on.
Also I'm not surprised to hear that Mitsu had no idea

[psproule]

Thanks guys - this helps quite a bit. I am going to ask the trans guy to at least take the back cover off and have a look for damage to the diff lock hub and 2WD / 4WD clutch sleeve.

Re the diff-lock detent switch. I have had a good look at the diagrams now and can see why the computer shows the correct positions. It is the left most switch of the three along the actual actuator shift rail and thus will show the correct position even if the shift fork is out of place due to the gear being incorrectly positioned. Bugger.

As you can imagine, a suitable letter is currently being written, acompanied by photos.

Pat

[psproule]

Looks like I was wrong about the shift rail drive gears being out of place (sorry Mr Mitsu mechanic). The diagram is misleading as it shows them both in a particular position at the same time. The way it actually works is that the rear gear is in the home position with the actuator rail all the way in, and the front one with the rail all the way out. It does not make reference to that anywhere but the trans guy worked that out fairly quickly.

So they are going to pull the back cover off it and start looking for damage. I'll let you know what we find. Cost of parts could get interesting.... I'm wondering if it may not end up more economical to source a 2nd hand replacment? Anyone know of rough prices or any good wreckers I could ring?

Regards - Pat

[psproule]

Just an update on where we are at with this (have posted similar on the pajeroclub forum)

Well, the transmission shop promised to tear it down and have a look but warned that the likely failed parts would be very expensive. I suggested that in the meantime I would price a second hand unit and get back to him.

A week later and he hadnt had time to tear it down, but meanwhile I had turned up a transfer for $500 from a Sydney wrecker and we decided that this would be the easiest way to go. So I dropped it off to the trans guy to swap them over. Another 4 days and :

Problem #1 - the wrecker supplied a transfer from an auto even though they said it was from a manual. Ugh! It turns out that they are quite different - different shafts, mounting plate, oil capacities, missing hole for manual shifter. He had a look at swapping the required bits but it was looking too difficult.

Problem # 2 - when he split my original transfer and transmission he discovered that the output shaft of the transmission is just about stuffed. All the splines are rusted out and about to shear off. Interestingly - this turned out to be RallyPaj's problem with his transfer failure in the other thread - his actually did shear. And I have also just heard of a Gen II doing the same.

I have now sourced a whole transmission / transfer from another NM @ $1650 - we will see how that goes.

Pat :(

[psproule]

.... and now the wreckers have discovered that the one they have in stock is from a GL - ie not super select II.

ARRGGGHHHH - will this ever end?

Pat

[psproule]

I've found one... Before I exchange the transmission, transfer and $2,400 for a S/H one I
thought I would take the back cover off for a look-see. The results can be
seen here:
http://athene.csu.edu.au/~psproule/transfer/transfer.html

Re the failed transmission output shaft... I have now heard of 3 others that have worn the splines right off - one of them had done it twice. It was regularly used for towing ski boats. Ours probably wasnt far away from doing same.

Pat