Clunk-vibration When Starting Off

[mlochala]

I'm having an issue that I would like some help trying to diagnose before I climb back under my Mountaineer. As before, it's a 1998 Mountainer 5.0 that was originally AWD. I have since removed the AWD unit and shaft.

When first taking off, I'm getting a sort of bump-slip-bump vibration from somewhere in the drive line. After I get going, it doesn't do it anymore and there is no vibration. It didn't do this until I removed the front AWD unit last year and so I've just assumed it was the viscous clutch and that it was normal. But, it seems to be worsening.

It almost feels like a rear end slipping, but there is no roaring noise coming from the rear end. I won't be able to check it out until this weekend.

My initial thoughts are the following:

1) Viscous clutch slipping due to removal of AWD front unit. I've not seen
anyone else complaining of this.

2) Slip joint on drive shaft needing lubrication, but I think if it were this it
would be more loud and would be present at other speeds. Also, it
would not be slipping, just making a clunk noise. Am I right on this?

3) Rear brakes not releasing properly. It does almost feel like the chatter
of brakes that are grabbing. Is this possible????

4) Possible u-joint going bad. But, wouldn't this vibrate at higher speeds
too?

5) Rear end going bad? Possible ring & pinion slippage? But, wouldn't it be
noisy and have some vibration at higher speeds? I sure hope it's not
this because I sure can't afford to replace that right now.

 

[mlochala]

Any suggestions?

 

[yavapaires]

I'm having an issue that I would like some help trying to diagnose before I climb back under my Mountaineer. As before, it's a 1998 Mountainer 5.0 that was originally AWD. I have since removed the AWD unit and shaft.

When first taking off, I'm getting a sort of bump-slip-bump vibration from somewhere in the drive line. After I get going, it doesn't do it anymore and there is no vibration. It didn't do this until I removed the front AWD unit last year and so I've just assumed it was the viscous clutch and that it was normal. But, it seems to be worsening.

It almost feels like a rear end slipping, but there is no roaring noise coming from the rear end. I won't be able to check it out until this weekend.

My initial thoughts are the following:

1) Viscous clutch slipping due to removal of AWD front unit. I've not seen
anyone else complaining of this.

2) Slip joint on drive shaft needing lubrication, but I think if it were this it
would be more loud and would be present at other speeds. Also, it
would not be slipping, just making a clunk noise. Am I right on this?

3) Rear brakes not releasing properly. It does almost feel like the chatter
of brakes that are grabbing. Is this possible????

4) Possible u-joint going bad. But, wouldn't this vibrate at higher speeds
too?

5) Rear end going bad? Possible ring & pinion slippage? But, wouldn't it be
noisy and have some vibration at higher speeds? I sure hope it's not
this because I sure can't afford to replace that right now.

If the ring and pinion were slipping you wouldn't be going anywhere. I would look at the slip joint. To test for a bad u-joint, let off the accelerator slightly at cruise speed,( neither accelerating nor decelerating) if a u-joint is bad you will feel a vibration. The vibration should quit when you either accelerate or decelerate, unless the u-joint is completely shot.