This is a 2000 with a Warn4406 Torque on Demand transfer case.

When driving along at 55 or more, I get a momentary "chattering" under my feet on hard acceleration. Goes away when I let off the gas. Sounds something like a U-joint or a motor mount.

Pulled out the front driveshaft and the noise is gone, no matter how hard I push it. The U-joints are fine and while the slip yoke is greased, it may be a little sticky and this may be causing the problem.

I'll lube the yoke with Ford PTFE grease and see what happens.

I suppose this could be transfer case, but just guessing. As I see it, the transfer case only engages the front driveshaft if the rear's slipping so at high speed on dry pavement, I don't see what can be going wrong in the transfer case.

Anyone have any thoughts on this?

Thanks for the help!

Eddie in New York
2000 Expedition XL

 

Nobody have any ideas?

 

Replace the oil on the TC and observe, mine does that and it goes away when I change TC oil, just ~2 qts synthetic ATF. I use Mobil1 ATF, you could use any synthetic ATF that you fancy.

 

Tried that last year, with no success. Used regular Mercon. Do you think synthetic would act differently?

 

I seem to recall reading it calls for synthetic ATF.
Also, I change mine around once a year /12k when it starts to make the chattering noise.

Btw, I used to use a tiny metal oil pump I got from NAPA and it's a PITA, then I found this plastic pump from Autozone ('OEM' brand) that fits right into Mobil1 1-qt ATF container -made the job uber easy.

I hope the issue is this simple. GL.

 

Thanks, GL. You know I'll give it a try!

 

Took apart and greased the slip yoke with Ford Teflon grease, and changed the transfer case fluid, replacing it with Royal Purple synthetic.

The problem is gone.

 

Good to hear.

What's involved in slip yoke greasing, never done that before. Is teflon grease required or ordinary grease will do?

 

In a case like mine, I want to do it by the book. If you don't have such a big problem, you can simply remove the boot and stuff some grease in it.

The right way means dropping the drive shaft. Mark (index) both ends so you put it back the same way it came out. Otherwise you may have a balance problem. There's two nuts holding a guard on the transfer case end that have to come out. Use a long extension and a short ratchet handle to get them off.

Then you remove the metal clips that hold on the sliding yoke rubber boot on and separate the halves of the shaft. The shaft halves are keyed so they only go back on the same way.

I cleaned off all the old grease, dried the splines and replaced it with about 3/4 oz. of Ford's special PTFE blue grease made for these joints (Motorcraft XG-8 - ML1167/31508-42027). A 4 oz tube is about $8.

Put the boot back on with nylon tie-wraps which aren't as good as the metal Ford clamps, but I don't have the special tool for crimping these. If you're careful and use a needle-nose pliers, some say you can reuse the steel bands re-crimping them with the pliers or Visegrip.

The end with the joint goes closest to the transfer case.

Normally, you know these joints need lubrication when you get a "thump" when starting off the line. At least that has been my experience with rear drive shafts that have them. In the past I've lubricated them with regular grease. In the past it stopped the thumping.

In this case regular grease did nothing to stop the chattering. The PTFE from Ford worked.

 

Thanks for the detailed instruction - I don't have any issue as you described right now but will 'pin' this for possible future reference.

- OrleeC