pridero

At about 75 miles into a 100 mile trip, I was running up a long grade when it sounded like my drive train broke. Looking under the truck expecting to see horrible things, I saw the following: All bolts connecting the front drive shaft where gone and the drive shaft was resting on the cross member, One of the bolts attaching the Getrag to the bell housing had worked itself out, the head of the opposite side bolt had sheared off, top bolts tight.Transfer case in neutral hand spun it without any noticeable issues. Went ahead and drove off and was able to make it the last 25 miles. Here is the remaining issue: The Getrag shifts up fine and operates as it should under load but as soon as the tranny is unloaded it makes a bad sound. It sounds like a hammer is beating on metal really fast. One more item that may be a clue. My 4x4 engagement light has been blinking on and off as I drive. I assumed it was a bad connection or switch as the transfer case operates fine. Now I'm thinking I may have been driving it with a partially engaged case. Is my getrag failing? If so, how long do I have before it fails completely. Its my daily, so I will baby it as long as I can. Thanks.

BearKiller

To understand sort of what happened, it must be pointed out that a "married" transfer-case puts a TREMENDOUS amount of leverage against a very weak bell-housing/connection.

Like column-mounted accessories, in-tank fuel-pumps, rack-and-pinion steering, and FWD engine/transaxle assemblies, they are not used because they are better, but to speed up and cheapen the assembly-line process.


I am gonna bet that that missing bell-housing bolt did not back out of it's threads, but was yanked out by the roots.


Your bell-housing might very well also be cracked.



I had a very similar incident once with a 4x4 Chevy 4-speed NP-205.

Big trailer in tow, I was cruising along about sixty-MPH, when KER-SLAMMMM!!!!, and then the rear drive-shaft went dancing across the road.


What caused this was the big nut that holds the transfer-case yoke backed itself off.

When the spinning shaft started wobbling at the very last edge of the splines, it siezed while the U-joint was trying to articulate and thus slammed the whole driveline HARD, just before slinging loose.


I am sure there was more damages, but the ones I recollect most are :

It sheared the rear-end yoke.

It snapped a mounting "ear" off the transmission.

It split the bell-housing like a water-melon.



I had no indication that there was anything wrong with the bell-housing, until I got everything else put back to rights and tried to drive it.

I could push the pedal plumb through the floor and the clutch still not release.

I crawled under the truck while someone else worked the pedal.

When the pedal was pressed, the bell-housing spread apart, and went back together as soon as the pedal was released.




I figure upon closer examination, your findings will be similar.

BearKiller

The blinking indicator-light was probably caused by the front shaft being about to fall off; and, as it rotated, it was "kicking" the transfer-case enough to momentarily engage the light.


It could have knocked a hole in the oil-pan.

BearKiller

I am gonna add that many transfer-cases, especially the NP-205, hydraulically DRIVE the front shaft at a very high RPM when the shifter is in the 2WD position and the hubs are un-locked.

This front shaft spinning is not intentional, but it happens none-the-less; which is why the C-V-joint and fore U-joint will wear out so quickly on a street-driven truck that is seldom put in 4x4.


Your little episode should be a wake-up call for all the rest of us to crawl around under our trucks with a hand-ful of wrenches, checking the tightness of the many fasteners under there.

93flatbed

And some lock tight! I've had problems with the front drive line on all of my piles! I would just tighten them up each oil change until I had a vision in a dream...Lock tight.
50k or so on my extra cab and still no loose bolts!