De-acceleration Vibration at Highway Speeds

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Alan Peters

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The best way to describe it is the trac will shake say when de-accelerating around 65 to 50 mph. Anything over 55 you can feel a small vibration. I'm thinking U-Joints since I had the tires rotated and balance. Any thoughts??
 
I'd follow up with the rear driveshaft has almost no play but the front shaft does move somewhat. Also I found an end link that which the bushings have fallen off. These are moog end links. Possible cause maybe?
 
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Probably not u-joint. They vibrate on acceleration and quit when you take your foot off the gas. Thats always been a quick way to diagnose the possibility. Could have a problem with a front bearing or I have seen dirt or Blacktop on the inside of a wheel cause this.
 
Al, is your trac raised or lowered? If so you would need to compensate the end link bolt length. Or it might break a bolt or crush the the bushings. Locking nut might have been too tight. The bushings may have split.
 
They are Michelins Latitude Tour tires. I did have them rebalanced and the end link replace this morning and the vibration is gone on the deacceleration. I do have Moog ball joints as well so I greased them also. The trac is stock height. The tires were not too bad. I also had the alignment checked and the toe on the driver front was .59 degrees in. All these corrections may have fixed the problem. I'll drive it a few days and post an update if other members run into this issue.



I do have a steel driveshaft even though my built date is March 2003. So members have had them replaced, but the trac never really shakes above 70mph.



I west through each suspension part underneeth and didn't see anything loose. But my question is the toe being that far out cause a vibration?



Big Al
 
I have to agree with Eddie. I have been doing alignments for 20+ years now and hav never seen a toe issue cause a vibration..typically an alignment issus doesn't cause a vibration unless ther are worn parts also. I also find it odd that the end links could cause a vibration on decel but stranger things have happened.
 
Have you tried putting the truck in neutral at 65 and let it coast ???



Eliminating the load on the drive train may help you diagnose it......



IF it doesn't vibrate then it is drive train related... IF it still does, then i would suspect something else....



Could be a rear end or driveshaft...



Todd Z
 
Could over tightening the lugs cause a vibration? The receipt for the rotate/balance is marked at 150lbs ft/tq?
 
The lugs should be 90 to 100. If torqued them with the rotors warm, they might warp. Especialy if they dindt do a proper sequence star pattern torque.

They will especialy show up on braking. Warped bad enough you will feel them all the time. As the pads are always slightly rubbing the rotors.



If they actualy did 150. The threads in the lug nuts are most likly streatched. The lugs are ussually softer metal than the studs. But the studs can stress crack and break also.
 
I'm having a similar problem. Around 25mph and then again around 62mph. Horrible shaking. Just checked one rotor and it looks alright (tightened the rotor back on and spun it). Going to check the other.



Unlike Al's problem, mine is constant while on the gas maintaining speed...
 

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