Transfer case seems to be putting itself into 4H

[jaido]

not exactly sure how to explain this but even since a 4wd trip a few months ago, my transfer case is randomly putting itself into 4H, I will take off from lights and it will just slip itself down into 4h, slowing down to go around corners and when i accelerate again it will do it. like i can be doing 80ks and i can hear the gears grinding coz the lever and transfer is tring to go into 4h.
I have auto locking hubs could this have anything to do with it? or could my transfer case be buggered, ive looked under the car and theres nothing stuck on any of the linkages. im about ready to just cut down a old broom stick and jam it inbetween the transfer lever and my center console.

And also another thing, my car makes a weird grinding noise sometimes in the mornings when i take off and the noise wont stop until ive slowed down to a complete stop and then there is like a massive clunk like as if something is going back into a spot where its ment to be, i first thought it might have had something to do with my swivel hubs because they were leaking, but thats all fixed and ive still got the problem. only thing i could think of is could that be related to the transfer case issue and i just think its the front end because its echoing up to the front of the car. or could there be something wrong with my front diff when the air locker got installed. And i never drove the car before the air locker went in because that happened when i was doing the engine conversion

[tuckertrucker]

It shouldnt be your hubs mate as they only engage when theyre driven. And even if theyre engaged all they'll do is turn the axle, diff and front drive shaft which is no problem when the transfers in 2H.
If you've got a problem with your front diff lock it shouldn't affect your transfer because if the diff is locked, all you'll get is binding across the front axle, and the front drive shaft will turn. But because youre in 2H the front drive shaft isn't engaged to anything.
I'd say your problem is, like youve said, in your transfer. And it is 'slipping' out of 2H into 4H. Im not too familiar with the inner workings of the case so someone else will have to come along and fill us in. But the problem will have to be in there.

This 4WD trip you did, did it involve any prolonged submersion in water / mud?
I could be wrong so someone else come in on this one.

[jaido]

nah, 4wd trip was quite short, i did a power steering hose.
Could i have damaged anything because ever since ive had the gu ive never reversed to unlock the front hubs like the manual says.

[happygu]

No, the transfer case won't be affected whether you go into reverse or not .... I never have and it doesn't affect mine.

Sounds more like a link issue between the lever and the case....

[the evil twin]

Some strange issues there... you can change from 2H to 4H 'on the fly' in a serviceable vehicle so that shouldn't be a "grinding" issue anyway.

How many K's on the vehicle?

When you say it is going into 4H does the 4WD light illuminate and the lever go all the way from 2H to 4H?

How long before the "4WD trip a few months ago" was the vehicle operating normally?

If I had to go with a theory I reckon there is maybe a few issues and first one to sort out is there is a good chance the Auto Hubs are chewed out or packed with too much grease after the swivel hubs were serviced.
Lock the hubs and see if the grinding noise goes away.

Who installed the Air Locker? Is there a possibility the install is wrong or diff is shagged?
Reason I mention that is because perhaps there is enough backlash from faulty components to drive back to the transfer case

[jaido]

185k

yes the green light iluminates, thats how i know its happening so much, i can be driving along the hwy and see the green light flickering coz its trying to engage.

the cars been fine up until i went 4wding. and locker was installed by a mechanic who does the lockers for the local arb store.

[tuckertrucker]

Im just thinking aloud here so take note that I could be totally wrong.

When the hubs are locked the wheels will turn the axles and vice verca. When the diff is locked the two half shafts will turn at the same speed. When the diff turns the drive shaft to that diff will turn with it - and vice verca.
But when the transfer case is in 2H, the front drive shaft is not engaged to anything and so is free to turn in anyway it likes with out affecting anything in the transfer case, transmission or rear drive components. Hense why leaving the hubs locked in 2H is no problem because although they will turn the front drive shaft through the diff, the front drive shaft wont turn or engage to anything inside the transfer case.

This is where I start thinking aloud:
Presuming its a TX12A transfer case. The TX12A case is a chain driven transfer case with a big assed chain connecting the front drive shaft to the main drive shaft running through the transfer case. The sprocket that engages the front drive shaft to the main drive shaft is floating on bearings on the main drive shaft. This allows the main drive shaft to turn inside the sprocket without driving the sprocket (and hence through the chain the front drive shaft). A dog gear is splined to the mainshaft and is hence permenantly engaged to the mainshaft. The dog gear is free to slide back and for'd as to engage and disengage with dog teeth on the sprocket. This is how the main drive shaft is engaged to the front drive shaft. I've attempted to draw what I'm describing here.

Like I say, I've never had one of these transfer cases in pieces, this is based on a single speed transfer case from an old toyota that didnt have low range. But if this transfer case works in this way, it may be possible for the dog gear to have too much free play, perhaps in the linkages, allowing it to slip back and forward and engage against the sprocket.6231462314