So I need a little help in the "what to do next" in the quest for me figuring out my problem with the 4wd.

1992 f350 crew cab 7.3 non-turbo 209K

When I lock hubs and engage 4wd I am getting a super loud rotational clunk noise. Example. Clunk, tires roll a foot, CLUNK, roll a foot, CLUNK.

If the hubs aren't locked and I engage 4wd so the shaft moves, no clunking. It only happens when the hubs are locked.

So, as I don't know a thing about these differentials...when the shaft is moving, is it meshing with the differential? If so, then maybe I need to look to the hubs as the issue.

If not, then how do I differentiate between a hub issue and an internal issue in the pumpkin?

I will add that I installed a used transfer case, new front axle and new front knuckles last year. 4wd worked just fine the remainder of winter. This issue just crept up this summer when I had to put the truck in 4wd to get the boat of a slippery launch.

 

These are manual hubs correct............

Have you checked the universals.......

 

Defiantly sounds like a u joint in the front axle. I would check them.

 

Both u joints were replaced when I replaced one week before the transfer case.

Not saying that they couldn't be bad, but I had disassembled the entire hub to replace them because you could grab the knuckle and rotate it back and forth the joints were so badly worn.

And yes, manual hubs. I'll run out and check for play. Just got home.

 

Check the front drive shaft U joints as well.
With the one foot distance I also think U joint.

 

Also, when you replaced the u joints in the front( I don't know what axle you have) but, Did you make sure the U joints were in time? Just curious.

 

No I didn't make sure they were in "time." Can't even say I know that that means. I have the solid front axle.

So a little more to the story....

I checked all u joints in the front and front drive shaft. All are nice and tight (before replacement they were really sloppy.

So, the noise has also changed. In a straight line (not towing the boat) there is no more heavy clunking noise. On the other hand, if I am in 4wd and make even the slightest turn (on wet pavement), same clunk, just a lot quicker. Clun, clunk, clunk as i am turning with almost no distance between clunks.

I had someone stand out side to see if we can determine where the noise is, but it sounds like it is directly under the truck. If I lock only one hub, the noise doesn't occur. When i lock both, it's on like Donkey Kong.

I know you guys will tell me that you always will get a bind in 4wd on pavement but this is stand 30 feet away and you can still hear it, and it happens immediately once the wheel is turned.

What's next, I don't know. I can't isolate side to side, so maybe that becomes a front diff issue?

 

I wonder if someone has installed a limited slip or locker in the front differential?

What you are describing almost makes me think you may have a locker.

As for the binding when in 4x4 on pavement going around a corner, turn your wheel hard in parking lot and stop in the middle of your turn.
Now mark the outside of each tire with chalk.

Next find the center of the circle.

With a crew cab long bed, the front tires travel feet farther around the circle than the rear tires do.
Since they are mechanically linked together turning at the same RPM in the transfer case, something has to slip somewhere to relieve the stress when the drive line gets wound up.

 

iv never heard a quite 4x4 on pavement. what your describing sounds perfectly normal to me.along with each clunk,you may feel wheel hop as well.
try 4x4 on the grass/mud/snow and see if your "clunking" stops.
the passenger side outer wheel U joint is supposed to be installed,so that the passenger inner U joint turns together/they should look like they are lined up in harmony with each other,not staggered.this is for the "timed" reference above.iv never made this mistake,so i dont know,but this may be why your hearing it clunk without turning the wheels.hmmm.

 

Call me crazy but I think I only have 2 joints a left and right; no inner and outer passenger side. Again, this is a solid front axle.

As far as the locker issue, I don't know. Can I just lock one side? I guess if I need 4wd in a pinch, I could just lock the driver side or passenger side.

 

lock the hubs, but leave the transfer case in 2 wheel and see if it still makes the noise. if it does, it is in the front axle.
if if is quiet, then put it in 4X4 and try it on wet grass or sand. if it is still quiet, it is normal.

4X4 and hard ground make weird noises appear out of nowhere.

 

If I lock the hubs, I can drive all day long with no noise so long as I am not in 4wd.

Is it posible I have something going on in the transfer case that would be reflected on turns only? The case is used, but I just don't see how it could be an issue. The front driveshaft that connects to is brand new (well, installed last year but only has about 5,000 miles on it if that).

Are the hubs on these cars known for failing where maybe they aren't truly fully engaging and that's why you hear the pop? I've done nothing with them yet.

 

i would jack the truck up on all 4s and try spinning the front and to find the noise, if not maybe run it slow in 4x4 to see if you can isolate the noise.

 

I believe there is a spindle bearing. not to be confused with the inner and outer bearings on the hub.

This could be the problem. does your u-joints (before going into your spindle) have any side to side or up and down play in them. if so your spindle bearing could be shot.

 

I am going to say everything is normal then.

Like I said, when in 4x4 the drive shafts are both turning at the same speed.

But in a corner, the front wheels have to travel much farther than the rear wheels, so the drive line winds up till one of the wheels slips.

With enough weight on all four tires, a sharp turn in 4x4 on a high traction surface would mean broken parts like an axle, U joint, transfer case or drive shaft.

All wheel drive and 4 wheel drive are not the same thing.