This is my last resort in finding what my problem is.

I recently purchased a 96 F-250 4x4 Std Cab with an 8 inch lift and about 100k on it.

A month ago I discovered a metal on metal clanking noise at highway speeds. I brought it to my local Ford dealership and they told me the transfer case was empty and pieces of metal where in the bottom of the case, and they replaced it. Deffintly my fault for not checking sooner. But at this point I had only put about 200 miles on the truck.

A day after picking up the truck with a new transfer case, we had a good 8 inches of snow and before I left the house I locked in the hubs (they are manual) and there was a loud whining/griding noise from the front end (not typical 4wd noise) and as the speed increased so did the noise with speed at anything over 30 it sounded like the front end would blow up. This was the first time I had locked in the hubs and driven, keep in mind I am still in 2H on my way to dealer I need to put in 4H to get through the snow and the noise got worse and louder yet on decel. So after limping back to the dealer and taking the tech for drive we began tearing the front end apart to find the problem.

The front driveshat was in good shape U-joints where solid. manual hubs in good working order, Wheel bearings good, Inner hub axle bearing good, half shafts and u-joints where also good, some play but nothing out of spec for 100k mile truck. Then we began tearing apart the front diff, the spider gears where binding on every 1/8 or 1/16 rotation, so we figured we found the problem. I order the spider gears, and all new bearings and seals for the diff dropped of the parts and waited to hear back after 4 days (today) I got a call from the service manager and said my truck was back in one piece and still making the same noise with the hubs locked in and worst in 4wd. The tech in a desperate move replaced all the wheel and hub bearings and seals.

So I went there this afternoon for another drive with the tech and they weren't kidding same noise. So I told them I will take the truck back as is and began troubleshooting on my own. They where very accomedating and only charged me for half the labor and told me if I find the new transfer case is the culpirt to bring it back and they will replace it under warrenty (nice of them since it's brand new).

So after doing some digging on the internet the only thing I can come up with that would cause this noise would be possible front driveline angle issues. My logic is this, hubs locked in, Tcase in 2wd the front drvieshaft is spinning making noise due to bad angle, Tcase in 4wd drvieshaft is now being driven under load and the noise gets worst.

I have seen that they have double u-joint and cv driveshafts to remedy driveline angle problems on lifted vehicles, does anybody out there think this is my problem, or think it's something else. I am open to all suggestions and critism for not test driving the vehicle in 4wd.

 

I am more familier with the 4x4 setup on dodges after having worked on them quite a bit. I imagine the basic setup is the same on Fords. A metal on metal clanking sound could definitely be the driveshaft binding under a high angle. They will clank or pop on each rotation usually. As for a whirring or grinding, that doesnt really describe the sound of a binding shaft, but more of a shaft with bad bearings. CV joints are not put on shafts to allow them to operate at a higher angle, but to cancel any vibrations since the pinion angle is different than the t-case yoke angle. you would be better off with just a u-joint at each end, but then you'd vibrate.

Is there any rhythm or pulse to the noise? I hung out the door of a friends truck and watched the d-shaft rotate to see if it corresponded with the noise. You have to start eliminating things one by one.

Good luck,