m4ff3w
m4ff3w UltraDork
2/15/13 9:39 p.m.

Can yall enlighten me about 4x4?

My '92 Montero has "Super Select 4WD" The transfer case has 4 settings: 2WD 4WD Hi open center diff 4WD Hi locked center diff 4WD Lo locked center diff

The truck is great in 2WD. If I shift the transfer case to 4wd hi there is much wailing and gnashing of teeth.

The same if I go directly to 4WD Hi Loc.

But if I go directly to 4WD Lo Loc 4x4 works as advertised, I can then go from 4WD Lo Loc to 4WD Hi Loc and all is well. But if I go from there to 4WD Hi with the open diff, there is more wailing and gnashing of teeth. Crunchy noises and vibrations.

Any ideas what the problem could be? The hubs are neither manual nor traditional automatic, instead it uses a "central axle disconnect" which appears to function as it should.

Swank Force One
Swank Force One MegaDork
2/15/13 10:47 p.m.

Make sure you're not going just barely past the selector where it needs to go. My Cherokee likes to do that if you try to go all Hulk Hogan on the selector.

But if pull on it pretending that you're a 6 year old girl, all is well.

Tom Suddard
Tom Suddard Intern
2/15/13 11:43 p.m.

How fast are you going when you shift?

crazycanadian
crazycanadian New Reader
2/16/13 12:46 a.m.

How and when are you shifting?? On the fly?? Most older on the fly systems use a set up that looks a lot like a standard transmission.. Where you have a fork that moves a locking collar.. It'll use a syncro ring to make the shift happen smoothly... usually the fork becomes spring loaded when you select the range change, until after the shift is completed..

You might have a worn out syncro set up... I wouldn't know for sure unless I pulled it apart...

You could also have a problem in your center diff from the sounds of what you described... I believe all of it is going to be in the same unit..

Woody
Woody MegaDork
2/16/13 7:00 a.m.

My only experience is with NV transfer cases, but is this shifted electrically or do you have an honest-to-god shift lever? The levers often need to be adjusted, which is usually pretty easy.

iceracer
iceracer UltraDork
2/16/13 9:17 a.m.

All four tires same size and mileage ?

m4ff3w
m4ff3w UltraDork
2/16/13 10:11 a.m.

All 4 tires are same size and mileage. The manual says you can go from 2WD to 4Hi at up to 60mph. I've tried it at all speeds from stationary up to about 30 mph, with the same results. I do let off the throttle when attempting to go into 4Hi.

When engaging/disengaging 4Lo Lock or 4Hi Loc the vehicle must be stationary and in Park or Neutral.

The system is a real lever with a "center axle disconnect" up front that is pneumatically controlled. The actuator works for it.

I'm not ham-fisted when I do anything, I'm usually afraid of breaking stuff. I'll try stopping the lever before it reaches full throw today.

Thanks yall.

crazycanadian
crazycanadian New Reader
2/16/13 11:13 a.m.
m4ff3w wrote: All 4 tires are same size and mileage. The manual says you can go from 2WD to 4Hi at up to 60mph. I've tried it at all speeds from stationary up to about 30 mph, with the same results. I do let off the throttle when attempting to go into 4Hi. When engaging/disengaging 4Lo Lock or 4Hi Loc the vehicle must be stationary and in Park or Neutral. The system is a real lever with a "center axle disconnect" up front that is pneumatically controlled. The actuator works for it. I'm not ham-fisted when I do anything, I'm usually afraid of breaking stuff. I'll try stopping the lever before it reaches full throw today. Thanks yall.

You are getting the noise because the system is trying to lock your front and rear drive shafts together... Thats a pretty simple way of putting it... There is a part in the t-case that will allow this to happen while you are moving... It has to be able to slow or speed up one of the shafts to get them to lock together.. I have had various other shift on the fly 4wd systems apart, but not your type... they all tend to work the same.. usually you have a syncro ring setup that works like a standard transmission.. this can get worn out... Sometimes the actuator for the front axle gets stuck and causes problems as well..

m4ff3w
m4ff3w UltraDork
2/16/13 11:55 a.m.
crazycanadian wrote:
m4ff3w wrote: All 4 tires are same size and mileage. The manual says you can go from 2WD to 4Hi at up to 60mph. I've tried it at all speeds from stationary up to about 30 mph, with the same results. I do let off the throttle when attempting to go into 4Hi. When engaging/disengaging 4Lo Lock or 4Hi Loc the vehicle must be stationary and in Park or Neutral. The system is a real lever with a "center axle disconnect" up front that is pneumatically controlled. The actuator works for it. I'm not ham-fisted when I do anything, I'm usually afraid of breaking stuff. I'll try stopping the lever before it reaches full throw today. Thanks yall.

You are getting the noise because the system is trying to lock your front and rear drive shafts together... Thats a pretty simple way of putting it... There is a part in the t-case that will allow this to happen while you are moving... It has to be able to slow or speed up one of the shafts to get them to lock together.. I have had various other shift on the fly 4wd systems apart, but not your type... they all tend to work the same.. usually you have a syncro ring setup that works like a standard transmission.. this can get worn out... Sometimes the actuator for the front axle gets stuck and causes problems as well..

But even if I'm stationary and in neutral and shift from 2WD to 4WD - open center diffI still get crunch noises.

Onetrillionrpm
Onetrillionrpm New Reader
2/16/13 5:05 p.m.

Output shaft bearing in the transfer case? Is the fluid in it clean? You could try laying under it with a trusted helper shifting it , while you use the long screw driver trick to help pinpoint the sound.

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