I have 2 Navis but am experiencing an issue with one of them. I just recently purchased it so I'm not all that aware of any mechanical history. Carfax/Autocheck didn't report any accidents and I cannot see any paintwork.
Issue: On smooth roads, the truck rides nice and smooth. No vibrations, shakes. etc. On roads that have some bumps and normal big city road patch work, the truck shakes and bounces extensively where it feels like you can lose her if you don't hang on tight to the steering wheel.
I noticed the 2 front tires are newer 20" Bridgestone's and the rears are the original Pirelli's.
What should I be looking for with this problem? Shocks/struts? A front end suspension part gone bad? Any help/direction guys...
Only judging by the description you mention here, I would make a guess as to your strut valve being faulty and/or worn out. Your strut's valve controls both rebound and compression of the strut during it's normal travel. If the valve is worn/faulty/defective, then it will allow the coil spring to bounce the suspension around while going over rough sections of road. I would do a good visual check of the front struts to see if there is any obvious leakage present which may present as an area of "stuck on dust" around the top or bottom of the strut rod.
You can do a quick test to see if the struts are performing as they should. The following video explains it a little better than I can although it's from the other side of the pond. However, the info is relevant and may help you pin down the cause of your problem. The most important piece of the vid is when the narrator describes how to check your "shock absorber". Give your Navi the bounce test and see what you come up with.
I suspect my struts are bad also-58K miles. The ride has become progressively bumpier. No sign of leaks, and bounce test doesn't show much. I think this is due to the coil over struts as opposed to older shock / spring setup. Without leaking, how could you positively tell a bad strut?