Vibration/Noise - Bad Transfer Case?

[Corvette1974]

Hello,
I just took my deuce to the NYC Veterans Day parade, and had an amazing time! It made the journey no problem, but on the way home, it started to make some sounds/have a vibration. The drive was about 65 miles each way, so everything was well up to temperature.
The truck has a high frequency vibration while moving under load, and more of a gear whine sound now. The transmission shifts flawlessly and the truck moves fine. I do find that when coasting to a stop in neutral (trans) the truck has a sort of shudder/vibration until it comes to a stop. I have not checked any fluids or done any in depth diagnosis yet, but the fluids all have less than 1000 miles on them. While I was driving at speed, I did flip the airshift for 4wd, and it made no difference.
All driveshaft yoke bolts seem tight, all input/output bearings seem tight. The transfer case in neutral is smooth, yet in either low/high the transfer case does have a noticeable degree of “notchiness” when grabbing and twisting the jackshaft (trans in neutral).
Any thoughts on what the problem could be?
-Will

 

[Corvette1974]

Sorry for the weird formatting, I copy and pasted from word!

-Will

 

[fsearls92]

Have you checked the jack shaft bolts, they might be loose causing the vibration.

 

[Corvette1974]

Have you checked the jack shaft bolts, they might be loose causing the vibration.

None of them were noticeably loose, but I will throw a wrench on them and see if they are loose. The middle driveshaft and rear driveshaft have all new bolts that only have about 300 miles on them.

-Will

 

[fsearls92]

You have to pull the center part of the floor pan to check the jack shaft bolts.

 

[Corvette1974]

You have to pull the center part of the floor pan to check the jack shaft bolts.

You do? I am familiar with the shaft (I just was turning it to feel the bearings)... The bolts are 100% accessible from the underside, unless I am losing my mind haha

-Will

 

[Jericho]

I had a loose jack shaft a few weeks ago, noticed the same symptoms driving the 150 miles back from the Weare Rally Tightened it up , but although the vibration seemed to lessen it was still there. Had a little notchiness in one of the Universals so I changes them both. reduced a little ,but still there Comes on around 35 mph and seems to ALMOST go away at around 48 mph, Has the feel of a universal, definitely rotational , can feel it in your butt, can almost count the bearings , If you find the cause please post it, Mine is already put up for winter . Changed all my fluids and added oil emulsiphyer l

 

[fsearls92]

Lol, no I doubt you are. Just personally have only done it with the cover off.

 

[Corvette1974]

Lol, no I doubt you are. Just personally have only done it with the cover off.

Haha probably a good call. The less I am on the ground the better! I'll let you know what I find out.

 

[Corvette1974]

I had a loose jack shaft a few weeks ago, noticed the same symptoms driving the 150 miles back from the Weare Rally Tightened it up , but although the vibration seemed to lessen it was still there. Had a little notchiness in one of the Universals so I changes them both. reduced a little ,but still there Comes on around 35 mph and seems to ALMOST go away at around 48 mph, Has the feel of a universal, definitely rotational , can feel it in your butt, can almost count the bearings , If you find the cause please post it, Mine is already put up for winter . Changed all my fluids and added oil emulsiphyer l

I am definitely going to check all of the driveline bolts. How did you check for notchiness in the u joints? Mine all feel tight/don't get hot but I'd rather be safe than sorry. I do know that I had a loos Rockwell input shaft bearing set and changed those, that took out a lot of the vibrations, but now a new set of vibrations is back!

 

[cattlerepairman]

Also check pinion bearings. Rode in a truck with one bad one and the vibrations were noticeable.

 

[rustystud]

Have you checked the jack shaft bolts, they might be loose causing the vibration.

I agree with "fsearls92" here. You actually need to torque them, not just put a wrench on them and assume they are tight. I had several that where "tight" but when I actually torqued them they where way off ! Also how are the 'U' joints ? When was the last time you lubed them ? Lube them now and see if it changes anything. You might have some going out on you.

 

[Jericho]

To check u joints with no load on joint turn it back and forth. Look for a shift in alignment along the longitudinal axis. If the shaft is out twist the joint thru its range of motion and look for , feel for stiffness or a notch flat needle bearing feel. As you twist it thru it's range of motion

 

[Jericho]

Grasp and turn the unloaded jack shaft , observe the longtudinal axis for misalignment, If the bearings are shot the joint will have looseness in it. Or if its removed, manipulate the joint thru its range of motion, As you wiggle it around you will be able to feel if its stiff or "notchy) meaning one can feel the individual needle bearings as you rotate the joint.

 

[Jericho]

And yes it can all be done from the bottom, plenty of room, All one needs is two good box/ open end wrenches

 

[Corvette1974]

Also check pinion bearings. Rode in a truck with one bad one and the vibrations were noticeable.

I replaced the front rear axle pinion bearings. They were noticeably loose - all of the rest *seem* tight. Is there any other way to check?

I agree with "fsearls92" here. You actually need to torque them, not just put a wrench on them and assume they are tight. I had several that where "tight" but when I actually torqued them they where way off ! Also how are the 'U' joints ? When was the last time you lubed them ? Lube them now and see if it changes anything. You might have some going out on you.

Lubed them all less than 1000 miles ago. Will lube again. I'll throw a torque wrench on them this weekend....

 

[Corvette1974]

Grasp and turn the unloaded jack shaft , observe the longtudinal axis for misalignment, If the bearings are shot the joint will have looseness in it. Or if its removed, manipulate the joint thru its range of motion, As you wiggle it around you will be able to feel if its stiff or "notchy) meaning one can feel the individual needle bearings as you rotate the joint.

Then by that metric, the joints are tight. They also do not get even remotely warm after a long drive, I am assuming it would be very hot if failing.

 

[Jericho]

if the bearings are going they get hot and the noise generally will alert you prior to failure , The pinion bearings hum, will have to think about it, I regreased every thing, and did the long bar flex check ( prying everything every which way) Bearings are pretty STOUT, hadn't given them much thought, Now you have piqued my interest, supposed to warm up to 30 degrees tomorrow , will have to look !

 

[Jericho]

I don't spare any expense on grease and lubricants, Good grease is paramount !

 

[Corvette1974]

if the bearings are going they get hot and the noise generally will alert you prior to failure , The pinion bearings hum, will have to think about it, I regreased every thing, and did the long bar flex check ( prying everything every which way) Bearings are pretty STOUT, hadn't given them much thought, Now you have piqued my interest, supposed to warm up to 30 degrees tomorrow , will have to look !

I don't spare any expense on grease and lubricants, Good grease is paramount !

Good fluids and grease were used. Less than 1000 miles ago everything was changed (even the steering box oil!)

Is there any other way to check for bad pinion bearings than lateral play? When I changed the front rear axle pinion bearings, it had noticeable (1/8 inch) play. The rear rear axle seems tight and the front axle probably only has 1/16 inch play at most.

-Will