Ok ive been to the shop twice over this and it still does it. After my truck has warmed up and especially on hot days, when i step on the gas i feel a light thump like the axle is loose. Not whenim driving the truck cold.I have put it in the shop twice as i said. The 1st time they worked on it for free under warranty and it never stopped doing it. The second time, some soccer mom pos ran into my truck in my driveway and smashed the rear quarter pannel in and bent the axle. They changed the entire rear axle out and it still does it. Anyone know what this is? They have told me my leaf springs need new bushings but i dont understand how and it only does it after the truck has warmed up. Could it be in the trans? Maybe the transfer case?

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I'm having the same problem with my 02 4x4 QC. Usually does it when i take off from a stop get a vibration in the rear. I'm having trouble with the trans shifting out of overdrive when I'm cruising at aconstant speed believe it could be the torque converter it does this constantly as long as its not under a load. Thought they were linked and was goingto have them checked out still have warranty, but they may not be after reading your post

 

Its not a vibration like say a harmonic engine balancing vibration from the pistons firing. Its a thump like theres play in the gearing or something. My engine also vibrates my truck when i take off with the stock wheels on it.

 

Bump.

 

Bump.

 

A biggity biggity biggity bump!

 

Lumps in the BUMP!