Hi all, have the strangest of problems with my '99.

On a 200 mile round trip the other day was rollying up the highway at aprox 70 mph (on cruise control) when there was a big clunk! Gear shift seemed to sort of jump, truck seemed to carry on driving normally.

Get home, truck operates fine, look under the truck and the front driveshaft is lying on the skid plate, the bolts are sheared off in the flange where it bolts onto the transfer case????????

Any idea what may have caused this to happen at highway speed in 2wd???

any ideas welcome.

Thanks.

 

Did you try to turn the output shaft of the transfer case by hand? Only thing I can think of for the moment would be a stuck bearing in there.....
Good Luck!
AlpineRAM

 

Yeah I will try and turn the output shaft and investigate further, just can't possiblyt understand what might have gone wrong when the front driveshaft shouldn't even be moving in 2 wd

 

Yea he has a point, being a 99, the front shaft shouldent of been moving when he was in 2 wheel, unless something wasent working right and the front end was engaged on the axle, spinning the shaft.

 

Sounds like it was indeed in 4-wd and they arent really designed to be ran on the highway in 4wd.. When was the last time you engaged/disengaged ?

 

Hold on. The front driveshaft is ALWAYS moving with this design, as it is always engaged to the left front axle shaft. When you shift into 2wd it disengages the transfer case from putting power to the front drive shaft and slides a collar on the right axle shaft so that the right shaft disengages.
My guess it something hung up, seized, etc., a bearing, whatever, in the transfer case and since the driveshaft is always engaged to the left axle shaft, something had to give, and the u-joints were stronger in this case.
Sure would be nice if we had lock out hubs.....

Chris

 

What i meant was that since the drive shaft always rotates a bit (even with the cad it will rotate at a speed depending on road speed and resistance in the varius bearings) and that the inertia of the shaft could snap the bolts if the TC output shaft gets stuck momentarily.
Good call on the CAD not disengaging completely, this would not be noticed while driving

AlpineRAM

 

seen an 03 on the side of the road the other day and it to had a broken front axle.

 

I know that my front driveshaft never rotates while I'm in 2WD. I used to have an oil leak that leaked on a certain spot on the shaft, and it only hit the top of the shaft. If the shaft had been spinning it would be evenly coated.

 

You have lock-out hubs then?

Chris

 

with an open front diff even though the driveshaft is engaged to the left wheel, all the spinning is absorbed in the spider gears. the only rotation of the driveshaft would be minimal and passive parasitic drag

 

That sounds logical, but if that is the case, wouldn't the driveshaft just stop moving if something seizes in the T-case, instead fo shearing the bolts off? I suppose we'll have to wait to hear what happened with Tool's T-case to know for sure.

Theorizing now:
Think about the fact that you can shift into 4wd on the fly, according to the owners manual, up to 45mph, but actually quite higher.
Now, if you consider this, if the transfer case was moving at a signifcantly slower speed, shouldn't you have a much harder time shifting into 4wd, even with a synchronizer in there?

And no, I have never actually clocked it, but I have never seen a front driveshaft on a Dodge not turning when rolling down the highway. Yeah, I actually look at that sort of thing.

Chris

 

Still haven't figured this one out yet......... To be honest haven't had any time to investigate. Been working crop spraying around the clock and such...

Need to figure it out ASAP.

The T-case was definitely in 2wd when this happened. 4wd gets used.... periodically at best anymore. Used to use it a lot more frequently when I lived in an area with a lot more mud and snow then I do now.

Stamey........ Just have to ask, how do look at peoples front dribveshafts when they are driving?? I don't think I can see mine unless I was almost lying on the ground.

 

Nope, factory front end for me. His driveshaft also wouldn't be turning, because after it flopped onto the skid plate if that baby was spinning while going 70 MPH he'd be getting a new oil pan for sure!

Tool, do you think it is possible that the bolts just rattled out? Were there still threads left in the flange? I've seen a few cases on here of these bolts working loose. This is about all I can come up with because your driveshaft wasn't turning, therefore the transfer case shouldn't have anything to do with it.

 

Well you gotta hang out the window just so....
I look at other Rams, as I ride down the road. It's easier when I am riding with someone else, on a vehicle that is lower than my truck, and I go tnothing else to do wen riding so...

Chris