hi all need some help with a 4x4 problem!

[jerryp40055]

4x4 prob

did not see the posts till after mine about the lights. yeah i don't trust the dealers. i can't afford a case new or used right now and with all the rain i don't know if i will drop the shaft today or wait till after the doc appts just in case i can't drive it.

 

[jerryp40055]

4x4 prob

from the pics i see 4lo 4hi/auto and n what does n do?

 

[IZwack]

[N]eutral, its just there because the engagement between 4HI and 4LO is an actual gear change and, just like a manual transmission, you need a Neutral stage between gear changes (see below). You can not, with the in-dash switch, get to Neutral because it is useless for drivers, it is only for the transfer case.

(Shifting from one gear to another in a manual transmission requires the shifter to pass through the center horizontal line of the shift pattern, which is neutral -- this is similar to the 4405 transfer case.)

 

[joecrna]

OK, stupid question but doesn't this transfer case use an electro-mechanical clutch (much like an air conditioning compressor) to engage the front wheel drive output shaft? What kind of a mechanical failure would prevent front wheel drive from disengaging? Seems this would be unlikely. Just trying to better understand how the 4405 case works. Thought I had it down but maybe not.

 

[gijoecam]

The system is similar in operation, although very different in design. In fact, IIRC, IZ had his fail in just that mode back in the day. (i.e. it locked-up) The ball-ramp mechanism in his was fractured, lodging the balls and ramp against the clutch pack, locking it up. The friction plates can fail and lodge themselves against each other, or the fluid pump could fail, leading to a catastrophic failure of the clutch assembly... Just to name a few.

Just like an air conditioning compressor clutch, the t-case clutch can (and does) fail.

 

[joecrna]

Thought it was pure electromagnetic and not a ball-ramp design. Must be similar to an Eaton E-locker diff. Can this clutch slip as opposed to "jamming" or locking up such as when excessive amounts of power are fed through it or it just being worn? I would assume so. Does power transmit from the input directly out the rear output shaft or is there potential for slippage here too?

 

[gijoecam]

From the input to the rear output shaft is a direct drive, so it cannot slip there.

Slippage between the front and rear outputs (i.e. through the clutch) is allowed while the clutch is disengaged, but not when it's engaged. I suppose that, with enough power, some slippage might occur with the t-case locked, but I have yet to hear of anyone pulling that much power from a 4.0 Liter motor and trying to force-feed it through a 44-05 case. Typically the trans will fail first, so with the new trans comes a plethora of other more stout mechanically-engaged t-case options.

For all practical purposes, the case is either locked or it's not. I've not experienced one that has 'locked' and still allowed slippage. We have seen a number of them on here that have remained locked when they should be disengaged, as evidence by the complete electrical disconnect resulting in continued driveline bind-up. That's why we asked you to unplug the connector and see if the binding problem persists. That'll quickly and easily narrow it down to being either a mechanical problem with the case, or an electrical gremlin with the control system.

 

[OldRedB2_84]

how bad is it to drive with it unplugged, mine just failed and i dont have the money to fix it right now?

 

[IZwack]

You wont notice any difference since the vehicles in question are 98 and newer -- just a blinking 4HI/4LO light.

 

[OldRedB2_84]

lol, they dont even blink. i wonder why?

 

[jerryp40055]

prob is the case

took the front shaft out today and as you guys thought the front wheels spin free now. i have been reading glacier991 rebuild diary and may try to see what the prob is some day. since i need the truck in the meantime are you guys sure it won't do other damage driving without the shaft? why are the dealer mechanics so sure that it will? thanks for all the advice so far you guys are all right on the money. by the way once i drove on the street for a few minutes the hi and low lights started to blink(six times each cycle)

 

[IZwack]

So just to clarify things, after you took the drive shaft, there is no more binding in the drivetrain and the vehicle can make turns w/o any problems? If so, then yeah definitely transfer case issue.

 

[gijoecam]

So just to clarify things, after you took the drive shaft, there is no more binding in the drivetrain and the vehicle can make turns w/o any problems? If so, then yeah definitely transfer case issue.

Ditto.

I don't know why they would insist that damage would occur. There is absolutely nothing that can happen because the front shaft is removed. The drive for the rear output is a direct-drive through the transfer case when it's in high range, so there's nothing that can happen there. They probably think (mistakenly) that the automatic 4wd is the same setup as the all wheel drive... it's not, but I've come across many techs and parts guys that are ill-informed as to the actual function of the 44-05 case.

-Joe

 

[joecrna]

The 4405 is definitely a misunderstood case. I agree, disconnecting the front output shaft won't hurt anything. The service guys probably also don't understand the difference in the front axle assembly (disconnect, looking hubs etc.). Not saying they don't know what they're doing, they just don't realize what years/models have which systems.