While trying to diagnose a new rattle this afternoon I noticed the u joint in my front drive shaft is failing. One of the bearing cups looks to have lost some of the needles as the u joint has play side to side. The ears on the drive shaft don’t look bent, hopefully I caught this before more damage occurred. While I research how to make the repairs I’m still ok to drive the truck in 2wd right? For clarity my truck has a C6 trans and NP208 t case w/ Dana 44 TTB front diff.

 

Locking hubs up front?
If so unlock them and put transfer in 2WD so the front shaft will not turn.
Now if no locking hubs I think you can pull the front shaft and put the case in locked so it will put power to the rear drive shaft.
Other than my 02 Durango they had locking hubs, the Durang has a slip shaft to lock the axles like the hubs would do from what I been told as I have never been under the truck but once in the 24 years to change the oil and that was the last as it will get shipped out it was that bad a job.
Dave ----

 

That might be your noise. Even if you are not in 4x4, the front suspension is bouncing up and down going down the road, and the front driveshaft is bouncing too, along with getting longer and shorter over each bump, even though it is not turning.

Check the slip joint in the front driveshaft, and also the slip joint on the pass side front axle and both u-joints out at each front wheel. All this stuff moves all the time, even though you are not using the 4x4.

 

I had thought of that being the source but the rattle I’m hearing sounds more like a heat shield vibrating. The u joint/drive shaft moving would be a deeper tone, more of a clunk wouldn’t it? This rattle is more like a repeated ting.kinda sounds like the fan rubbing the radiator but the fan doesn’t wiggle on the shaft nor does the radiator move.

 

Could be the shield around the cat converter. Most rust off and are laying in the road, but maybe yours hasn't fallen off yet.

 

Not always.
When a U joint is starting to go bad they sometime make a chirping sound when taking off from a stop and speeds up as you go faster but may not make the noise when up to speed.
I had a rear shaft on a 4x4 that never made noise or show signs of going bad till I got on the highway one morning and the vibration was so bad I could not drive it the 2 miles back home on city streets.
Walked back home got my other truck, tools and stopped by dads and parts and fixed it on the side of the road.

So that tin sound may be a U joint also, look for rust marks around the joint.
Dave ----

 

Hopefully friday I’ll have some time to crawl under and have a look. I didn’t see anything that looked off but it was still too hot to get hands on with much as I’d just driven back home. I also had the thought to just pull the front shaft and see if that stops the rattle. I figure it’s got to come out anyway.

 

Usually, that will work. Some Jeeps with certain transfer cases though, the front shaft has to be in place. I've never heard of a Ford doing that but there are some ay transfer cases out there, it's hard to say.

You're staying on top of noises and that's good. I'd lay in new u-joints before pulling though. You might have time to slap the new ones in. I've seen a bunch of trucks where the owner pulled the front shaft and never put it back in. That's when things like u-joint bearing straps get lost.

 

I hear ya. From the looks of it in these quick pics I took I don’t think its been out in a long time.



We’ll see. I haven’t even ordered parts yet. Realistically I won’t have time to really work on it until May, sadly.