I have a crazy rattling vibration when I hit 50mph. I jacked it up and put it on stands and got my buddy to bring it up to 50. My front output shaft starts spinning and my transfer case starts shaking like crazy.

My question is, is it normal for the transfer case to engage like that at highway speeds? I have a post going in the Excursion section but the average is 100 visitors vs 400 here and this problem is driving me crazy.

I have an Electronic transfer case with Manual Warn premium hubs that have been tested and are functioning correctly. The transfer case engages and disengages as it should and does not vibrate at all when engaged up to 50 mph.

 

That's not normal. I'd say you have a mechanical problem in the transfer case.

 

I have studied diagrams of the transfer case and can't seem to figure out what would cause it to engage.

 

That is not normal at all. Can you see the solenoid on the transfer case engage when the output shaft starts spinning? Or does it engage right away and then take a while for the shaft to start to spin?

Also, have you checked the transfer case fluid, ensure the transfer case solenoid and mechanism are lubricated, etc.?

 

I will be checking the solenoid on Monday, what should I lubricate it with wd40 break clean? I so far have checked it by engaging and disengaging the 4wd and it seemed to work fine. I'm just trying to wrap my mind around how the solenoid would cause this, maybe its not moving the fork all the way back/forward and its drag?

 

I would say that you have a bearing failure somewhere in the neighborhood of the front drive shaft engagement clutches that is allowing the clutches to make contact.

 

I was wondering if it was an internal issue with the transfer case my self but you think it would grab and start to spin at different times or grab all the time.

 

There is no way to know until it comes apart and gets inspected.

If you think it might have something to do with the electronic control mechanisms, unplug the wiring harnesses from the transfer case and see if it still does it. If it does, it's mechanical and the transfer case is going to have to come out and either be replaced or repaired.

 

I would lean towards an internal type issue, the bearings sound about right.

I have also seen the linkage the transfer case stick. The solenoid motor has pressure on the linkage, vibration gives it the additional motivation it needs to move, and then it vibrates the final travel to engage the transfer case. This would be obvious by looking at it. If you already have full travel then it is not something as simple as the linkage.

 

There is no linkage on the transfer case. The electronic shift motor is attached to the transfer case directly.

 

Ok thanks for the advice, I will disconnect the wiring and lubricate the solenoid and make sure the fork is moving freely and smoothly.

 

i have a 2008 450 dulley, 4wheel started trying to cut in at highway speeds,tried disconexing cable at transfer case no help. paid ford 400 dollars to find out the problem. they said it was the 4wheel drive moudle. it was behind the glovebox on right side. disconnected it no futher problems for 4 months, no 4wheeldrive now. approx 200 for part little over 100 to reprogram. may fix next year. good luck.

 

Thanks for the tip, I wonder if that is the "GEM" module or something different. anybody know if the older super duties have this and if its in the same spot?

 

On early model trucks (like yours) it is controlled by the GEM. In 2003 or so, the GEM went away and was replaced with individual modules, including the 4WD control module.

That is why I suggested disconnecting the connectors from the shift motor. That will render the shift motor inoperative and, if the problem continues, eliminate all of the electronics as a possible problem.

 

Thanks for the correction. I sometimes get confused between all the different Ford vehicles we own and I have to work on.