Last night we drove along a trail out into the bush near our place - some spots the road was quite muddy so we used 4x4 (4H) to drive through. Worked great.

However, now, back on the highway, with 4x4 off, I notice a brief rumble sound and sort of shudder when accelerating (gently) through 90 degree turns - like turning after a stop sign. I tried switching it back to A4WD briefly, then back to 2H, but the sound / shudder continues when turning.

Any thoughts?

 

My 2000 4x4 expedition does it too. Still trying to figure out why. I'm hoping your post provides some answers. Not sure if mine did it since I bought it ( spring 2007), I only noticed it after I had to change out the diff lube because of a puncture in the cover.

 

Strange. We bought ours about 2 weeks ago, so I'll be the first to admit I'm not used to what sounds right for this vehicle, but I had not noticed this feel / sound before, and I've been paying pretty close attention. It only started after we used 4H last night for about two miles of driving or less.

 

You guys has LSD rears? You may want to service the rear and change the fluid (with modifier). Doesn't explain the tie to 4wd use, but the description of shudder sounds an awful lot like the clutches binding.

 

After I changed my transfer case fluid, I drove around in my yard testing four high and low. Long story short, my vehicle was still engaged in four wheel drive - even after I turned the selector switch back to 2wd. I was on pavement making a right turn and I felt the tires grabbing. I forget what steps I exactly did but basically I put the vehicle back into 4wd and reversed and the transfer case finally disengaged.

 

Did it still do it when you had it in AWD?

 

What could be the problem is what is I think is called drive-line wind-up. Going into reverse allows it to disengage. I remember they did that when we took a jeep offroad tour in Sedona AZ. Before they went back onto hard pavement they shifted into reverse and accelerated pretty hard so it would shift out of 4wd.

 

An 03 like his has an Integrated Wheel End (IWE) that completely disconnects the axle from the wheels at the hub, which should keep things spinning free even if the transfer case stays in 4WD. That is why I asked if the noise went away in AWD sometimes the IWE, which is vacuum operated only partially disengages.

Here is a video showing how it works : YouTube - Ford F150 - 4 Wheel Drive Disconnect

 

You guys are amazing!

...we took it for a little ride tonight and I was able to duplicate the problem, which is always helpful. Put it into A4WD, and it drags one wheel or the other when turning. Put it back into 2H, still drags. Pop into reverse, back up less than 5 feet and hear something disengaging (I guess). Back in drive, all good.

Not sure if we have the LSD rear - need to crawl under there and look...

So, reverse fixes the problem, but that doesn't seem like a long-term solution. Any suggestions on how to fix this - for keeps?

 

Axle code is H6. I believe that is then a 3.73 limited slip rear end.

 

From what I know this is quite common on 4x4 vehicles and will happen when sharp turns are made. Now last time I used A4WD I never had to go into reverse to disengage it - but I never made any slow, sharp turns. When I was in my yard in 4H and 4L, making slow turns left and right the drive-line began to bind up and I needed to reverse to free it up. The previous owner of my 97 Expy told me this. I took his word because he's a Jeep guy and did lots of wheeling in his younger days.

Yes. That is correct.

 

Also, read this:

http://www.4x4abc.com/4WD101/def_turnpart.html

 

Thank you all for the help. I think what this has boiled down to is more of an education issue, and not so much a problem with the vehicle. After reading through the 4x4abc site that 97ExpGuy referred me to, it is all much clearer.

Again, many thanks!