2000 Expo-Vibation when turning

[I-HATE-CHEVY]

Hello,
We have a 2000 Expo, auto-awd, 4wd, Eddie Bauer model w/ the 5.4l Triton. I was a little leary about the Automatic AWD feature, as I am the type of person that likes to manually "shift" into 4wd. Hoever, we purchased this, all seemed to be well. Now, when we are turning to the left, usually, it has a slight vibration, acts as if it is in 4wd, but it does not hop around or anything. Is this a common thing for an awd vehicle? I have never experiences this, I was thinking it may be as simple as the alignment being off??

Anyone have any ideas?

Also, when I take off from a stop, there is another vibration, simalar to that of a lifted 4wd jeep or something that has the driveline not in the correct plane. Make sense to anyone?

So my wonders are : Is the is AWD all it's cracked up to be, and the vibration from a stop, is that indicative of a transmission problem in the future?

[fusion27]

i got the same problem with my 2003 exp, did you find out whats going on with that?

[I-HATE-CHEVY]

No, no answer as of yet, I still have not taken it in either, but I strongle feel is has something to do with this awd traction control thing. Not a huge fan of it, but I guess it's nice when you are in a situation.

does your have that same traction control?

Originally Posted by fusion27

i got the same problem with my 2003 exp, did you find out whats going on with that?

[fusion27]

yes it does, if you find out more about this please let me know, thanks.

[radeck]

Just my two cents.

I know exactly what you people are talking about and I've seen many threads about this problem in this forum. What I am about to say is pure theory, just because I am not car mechanic, but I have degree in mechanical engineering.

A4WD system will turn on 4WD whenever computer determines that one of the wheels looses traction. How does it know that wheel is loosing traction?? It compares rotating speed of each and every wheel. When let's say right wheel is rotating faster than left it means for computer that right wheel has not enough traction. In this case computer will enagage 4WD.

Now whenever you make tight turn it's normal that outside wheel will be rotating much faster that the one on the inside. If it is just a little slippery or tires are worn, outside wheel may be rotating just a bit to fast comparing to the inside wheel. That will make computer turn on 4WD. You will hear it and feel it right away.

I don't think there is anything we can do about it. If this system was a little less sensitive, it wouldn't be probably that effective in severe driving conditions. So whoever designed this system is probably aware of this turning problem and we will just have to live with that. Of course alligment may reduce it but still on tight turns and wet surface we will hear it working again.

Probably the only solution would be not to let this car make such a tight turns, but than would you like it like that. How would you park it???

I don't think there is anything to be worry about. Just don't force the steering wheel so much especially on wet, dusty, or just slippery road. Car reacts the way it was design to.

To prove my theory, turn the wheels all the way one way and just slowly release brake. Do not touch gas pedal. On dry surface car should work fine.

Do the same thing but press the gas this time. Outside wheel will start loosing traction and you will feel vibration from 4WD turning on.

Just be carefull making tight turns and don't worry... my 2 cents....