2009 versa strange wobble problem

[joshua5000456]

Ive worked at a nissan dealer for years first time ive ran into a problem like this. We aren't like many dealers we try to fix anything and everything that comes in no matter how long it takes unless the customer says otherwise this is the first vehicle that i dont what else to do with. versa has 87k miles on it. When you drive it, it seems as if the vehicle wobbles, not really a shimmy. I initially thought bent rim only thing i have seen cause this i rotated tires redrove vehicle exactly the same. The tires were pretty bad so i switched with another versa that drove fine of the line. I then test drove again exactly the same. I then put the vehicle on the rack and had a coworker driving vehicle in air at different speeds it doesnt occur on the rack, it seems to occur at 20-35 miles per hr so i was thinking maybe an axle shaft, so i switched the axle shaft off of the versa off the line and it still drives the same... so at this point i was getting frustrated put the vehicles side by side. doesnt occur in the air. Also had my service manager drive the vehile while i followed behind him we were trying to see if we could see something wierd while driving i just saw his head moving side to side with the motion of the vehicle, but the vehicle looked to drive perfectly. Before all this checked for bulletins which of course there was none. I thought it may have been due to the blown motor mounts on the right side, (pendulum mount, and engine mount) switched them and it did nothing. Found some play from a rear hub...not much... but i decided to switch that too. No suspension play in the front whatsoever. Im running out of ideas on this one. I also performed an alignment found that the specs were perfect. Vehicle drives perfectly at highways speeds over 35 and under 20 has no problems. I called the engineers (nissan techline) they sent over an engineer...he doesnt know what it is he says we should just keep switching parts of the suspension till we figure it out. Only problem with that is that we get paid flag time so i havent got paid on anything and will only get paid on the part that is replaced. have spent 8 hrs on this one already, vehicle has never been on a collision that has been recorded, and no signs of being wrecked. I have an idea on what it might be, but im getting tired of just hoping it will work. Anyone have any ideas?

[GPhaneuf]

I am experiencing the same problem with my new to me 2008 Sentra. If you find anything out please let me know. Thanks