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Dec 19, 2013 | 06:59 PM

richard crouse

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strange vibration.

help please.i have a 98 expedition 5.4 xlt. 4x4.i will start at the begining.lower trailing arm let go didnt know,rear end twisted up snapped drive shaft coupler to rear end.replaced u joint as drive shaft went winging under my truck.so replaced trailing arm, u joints.put it togeather.went to back up heard a bad noise found one of my upper arms bad,almost funny but not.so now my truck has all new upper and lower trailing arms.also a bone yard drive shaft that has been rebalanced three times trying to find this bad vibration.starts at 60 mph,however no vibration while foot in gas but if you take your foot out thats when you have a very bad viration.but if foot into gas at 65/70 and hold it there you get a very bad vibration.so if any body can help i would really be happy with any ideas.

thank you.

Dec 19, 2013 | 08:43 PM

pdqford

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From: Central NYS

Quote:

Originally Posted by richard crouse

,rear end twisted up snapped drive shaft coupler to rear end.

How tight did you tighten the pinion nut?

Sounds like a loose or worn pinion shaft bearings to me.

Dec 20, 2013 | 08:16 AM

richard crouse

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Well i didn't have to mess with that because the flange was fine and doesn't appear out of round, so never had it removed.the driveshaft separated from the coupling itself.

Dec 20, 2013 | 04:07 PM

pdqford

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Quote:

Originally Posted by richard crouse

Well i didn't have to mess with that because the flange was fine and doesn't appear out of round, so never had it removed.the driveshaft separated from the coupling itself.

Oh, okay. What you'r saying is the u-joint broke, or are you saying that the u-joint flange got ripped off the companion flange?

With all that violence under there, I'd put a dial indicator on the companion flange and see if there is any runout, indicating that the companion flange may have been deformed. Also check the drivshaft just in front of the rear u-joint to see if it turns true. If it is out a bit you can remove the four flange bolts and try the driveshaft in the three other positions to see if one is better.

And also check the companion flange with the dial indicator to see if there is any movement in and out of the diff. Again, that violence may have collapsed the crush sleeve enough that the pinion shaft is a little loose. (When the pinion is under power it can hold the pinion shaft tight, but when you ease off the throttle the shaft can then wobble a little if it isn't adjusted correctly.)

Dec 21, 2013 | 02:30 AM

richard crouse

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that is a great idea.i didnt think about trying the different positions.but i did find that my rear end is making some noise.gonna remove my diff cover and see whats going on in there.also my transfer case tail shaft is leaking,guess the seal took a hit when it all went crazy.pretty sure the rear end is going away.will opt for a good bone yard one from LKQ.will cofirm soon.thanks will let you know out come.

Dec 22, 2013 | 05:00 PM

developer

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I had this (not as bad) on my 99. It always had a vibration around that speed, but when the control arms rotted out, they were replaced with an updated version that changed the angle of the rear, relative to the driveline which eliminated the vibration.

Perhaps the arms you have are the original style? I don't know if there would be any difference between a 98 and 99 in that area.

It seems to me that when you accelerate, yours will squat in the back, changing the angle of the driveline to the rear.

Is it sitting higher now than it was before? I would check the part numbers to make sure you got the revised control arms - if indeed this was also a problem in the 98s.

Dec 22, 2013 | 06:11 PM

richard crouse

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did not know that,thank you.however i did confirm my rear end is infact bad.i put the rear up on jack stands got it upto speed and it makes some strange noise man.so yeah something bad did happen.not sure what but i will know soon.after christmas i will have time to do some investigating.for now i use her to go to work and thats it.i only work about a mile away so its not to hard on the old girl.i can only assume the pinion bearing and crush tube took a sever hit when all that took place.ya'know i love that truck man.

thank you so much for the input.