Vibration when coasting

[Dr.Doug]

I am throwing this out again for some comments.

I have a 91 EB. When the vehicle is COASTING in neutral or drive at speeds above 60 mph and no torque is applied to the drive line, I feel and hear a vibration from the floor. It sounds / feels like the vehicle is going over very small and close rumble strips in the road. When the vehicle is accelerating or decelerating, the vibration / sound is gone?

Rear end gears? U-joints? Drive shaft bearings in the transfer case? Drive shaft bearings in the rear end?

Any suggestions from others that have experienced this?

Doug

 

[Ira]

Had a similar problem with mine. It only did it at certain speeds. May sound like a long shot, but take a close look at your front tires. I found that mine (one more than the other) had cupping on the tread. When you look at the tread, this will appear as a tapering edge from the front or leading edge of each tread to the back of each tread "knob" itself. When I noticed this on mine, I took it and had the front tires trued up. They removed the tires on the front, put them on a machine similar to a balancing machine and it actually shaved the tread so that they were all even/level. They then re-balanced the tires and reinstalled them. I could tell a definite improvement as soon as I pulled off the lot. The noise I had heard before was gone. I thought this noise was just because it was a 4 WD. At highway speeds, I no longer had the noise or vibration. All this was done for a cost of about $20 total. It was well worth the money to me.

If you do have this problem, I would recommend grabbing the tires at top and bottom while the vehicle is jacked up and check for any play or movement in them. I found play in mine and attributed it to my wheel bearings. I tightened them up and now do not have the play anymore. Would not be a bad idea to check the front end alignment at the same time. Hope this helps.

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Ira

91 XLT 4x4

 

[Dr.Doug]

Thanks for the reply. The tires are new and have no cupping or vibration issues. I understand what you are describing but this is not the case here. Based on my automotive experience, I truly believe that the problem is in the drive line.

Pin pointing the exact problem with little time, effort and money are my mission.

Doug

[This message has been edited by Dr.Doug (edited 12-25-1999).]

 

[turbomark]

May sound dumb but check your lug nuts, u joint bolts and tranny mount.

 

[Dr.Doug]

I checked the lug nuts, u joint bolts and tranny mount. Any other remedies?

Doug

 

[Longs]

My gut reaction would be either U-Joints or Axle Bearings. Those parts seem to be most susceptible to load - sound changes when drivetrain is disengaged.

Just my $.02



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"Whoever said you can't fool all of the people all of the time, was a damn fool" Vincent K McMahon, January 1999

 

[Nick26]

Doug, its a long shot but wondering if you ever found the exact source of this problem. My truck has the exact same issue you described and I have a feeling its related to my differential gears/bearings (I installed a new carrier and locker a few months ago).

 

[Dr.Doug]

My Explorer is a 1991. On some early models, the bolt holding the flange onto the output shaft from the transfer case was loose. This was my problem. To determine this, drop the rear drive shaft and inspect the flange to determine if it is loose. You may be able to see this, without dropping the drive shaft, by simply pushing and pulling the drive shaft at the transfer case output. If loose, it will move slightly.

Good luck.

 

[Nick26]

oh ok, i actually fixed it last night anyway... all i had to do was go under and take a look to see that my rear most u-joint was shot. thanks anyway

 

[Rhett]

Glad you found it. Now...did anyone else notice that this is a SIX YEAR OLD THREAD RESURRECTION (!!) wow! The power of EF search.