So I was rolling down the highway about 70mph when I got a solid vibration, few miles later I was on the side of the road. Got a tow home by a Cummings. Last night we got the truck up on stands and notice the metal grinding noise was coming from the u-joints on the front drive shaft. After pressing out the u-joints it was evident that my drive shaft would need to be replaced to.

Now, my question is why was my front drive shaft turning while driving down the highway? Does it free spin until hubs are locked or does it only spin when the x-fer case is engaged?

 

I don't know the answer to your question, but it seems to me that it would only be when the switch was turned to activate 4x4. If the driveshafts both turned all the time, I'd think they would recommend the exact same fluid in both axles, which they don't.

Plus, there's a little clunk when you first engage 4x4 high. Not as loud as low, but a noise. I'd think this would be whatever slack was present in the driveshaft getting turned out.

Were you in 4x4 when it happened or were you recently before that (like since the last time you were in reverse)?

 

No, I have not been in 4x4 or turned my hubs in the last 2 months.

 

Your front drive shaft may turn, while not in 4X4. Are you referring to your axle shaft's or your Drive shaft? The front axle shafts also turn some while driving. If the axle shaft U joint's are bad they will usually bind your steering. (Usually make a tight spot, or make it pull hard from time to time) With this being said, nothing up in the front end, usually spin's at speed, UNLESS your hub's are locked, or your transfer case is engaged into 4X4.

There will always be a friction movement in the front end. As the hub assemblies/Transfer case still have a minor friction on the front system, if the axle shafts turn the drive shaft turns.

Check your hub's too make sure they are disengaged, Spin the front axle yoke and watch the axle joint's, they should turn easily, without powering the wheel's. Also check too see if your transfer case is disengaging, by spinning the drive shaft yoke on the front of transfer case , it should turn fairly easy too.

Again some movement is expected from the front component's of the truck, while running, but nothing should be solidly hooked together.

Maybe you have a stuck hub in the engaged position (caused by dirt or old grease in the hub assembly). Clean the Hub's up and put some good clean grease in them, while you are troubleshooting.

PS if it is just your driveshaft, and you don't need 4X4, just remove the driveshaft, it wont hurt anything to run it without one.

 

I've noticed when my hubs are engage but switch is in 2wd everything up front turns. When hubs are unlocked nothing turns. I have to keep my hubs locked in cause my rim center caps are a PITA to get off.

 

Thanks for the input!! I wasnt sure exactly how all that worked on the EX, not the same as the XJ i've played with.

I am referring to the front drive shaft.


Last night we tore down the front axle to check everything out-*found another possible issue I will post in another thread-* but everything in the axle looked pretty good(unit bearing,hubs,ball joints). There is minimal play in the axle shaft itself, not sure if thats a big deal or not? We re-greased everything when we put it back together. The right side hub wasnt as smooth as the left side, so we lubed them up as best we could using oil, cleaned it up and applied a little grease. Looking to install the warn units soon. Going back tonight and I will check to make sure the hubs are disengaging properly before driving home. I plan on driving the truck without the front drive shaft for awhile.

MOST IMPORTANT THING LEARNED ---

I had forgotten the fun to be had while turning wrenches with friends and cold beer.

 

Just to add a side note - my left hub is sticking a little, switching to the Warn units soon.

 

The front drive shaft shouldn't turn is everything is working correctly. I takes quite a bit of friction in the hubs and both front axles have to be suffering from the same problem for the front drive shaft to turn. Both front axles would need to turn and overcome the reverse ratio of the ring gear driving the pinion......not very likely. Just one front axle turning from some friction problem or any other reason won't turn the front drive shaft.

 

Yes, the driveshaft spins free until the hubs are locked and both need to be locked, or until the T-case if engaged, or both. It is controlled from both ends and when neither are controlling it, it should be still while driving.

 

Not sure what this means or what I should replace besides the hubs, but when I tried the above both wheels would spin. You could hold the driver's side wheel and it wouldnt bind up anything. I misspoke previously, its the passenger side that is sticking. You could not hold the passenger wheel and continue to spin the axle yoke.

 

It mean's, If you spun the pinion yoke and the wheel's didn't move, or could be stopped while still spinning the pinion yoke, everything is fine.
From what you described you found that something is hanging up in the P-side. Since you are replacing with Warn's, that problem should get solved.

 

I have had a similar problem on my 01 F350, mine is manual tranny and transfer case. Any time the xfer case was in 4x4 there would be a loud clunking sound. Originally I thought it was the hub bearings but after I inspected the front drive shaft I found it to be VERY loose and that turned out to be the culprit. All of the U joint pins were rusted out and the ball assembly in the center of the double U joint assembly was missing parts. and the insert the ball goes in was warped ( forgive me for not knowing proper terminology ).

My question is this a very common problem ? Will I likely see this problem again if I replace it with a salvaged drive shaft in decent shape ?

Truck has 8'' lift, and on humvee tires not sure if that matters.

Thanks for advice / opinion

 

When you check for friction in the front axles, leave the truck on the ground, unlock the hubs, and stick a large screwdriver into the front axle U-joints and turn.