TRIPDAGOAT

Ok, this is going to be rather lengthy so i'll appologize in advance.

Just purchased a 97 ZJ is pristine condition....Except a strange vibration

It is a very weak vibration that feels like it is coming from the front end/tranny area. it is only noticeable between 50-60 mph, and does not change with the speed or RPM of the vehicle. it is a surging vibration that comes and goes about 80 times per minute, and only when pressing the accelerator just enough to maintain speed. if i let off the power it goes away, and if i lay into it pretty hard it goes away. I only really notice it on very smooth roads. it doesn't feel like something is going to break anytime soon, but it is enough for me to notice and make me constantly think about it while driving. it feels kind of like those bumps in the road put just before a red light to get your attention, but much much weaker. it is too slow to be related to the engine (2500 RPM vs 80 Vibrations per minute), and too slow to be tire or driveshaft related for same reason. I tried to trouble shoot the transfer case as well by shifting into all 4x4 gears other than 4x4 low for obvious speed related reasons, and the noise continued on all settings. all four tires are very new michelin tires and the vehicle is completely stock. Do the gears in the transfer case spin slow enough to cause this vibration? Any ideas what to check out? Should i just ignore it the best i can?

ol"blue

I had the same issue with my '97. Try rotating/balancing the tires, and if you have the alloy wheels make sure you torque the wheels on. My vibration went away.

Kazman

x2 I had the same issue with my 98 ZJ, idiots at the tire shop didn't re-balance them after fixing a bead leak. They tried to just mark the tire where the valve stem was and re mounted them. Once I got them to balance them properly, vibration was gone.

TRIPDAGOAT

Well i thought about that, but just didn't seem like that would be the case since its a surging vibration and its way slower than the tires are spinning. i'll give that a try though since you both say that was your problem. Thanks a lot for the help guys.