Vibration after rebuilds

[asymptonic]

Just got the Jeep back after a full AX-15 rebuild and a rear axle replacement (rebuilt 8.25 chrysler 3.07). So all of that stuff is "new". That said I'm having two problems, which probably aren't related. Mostly I'm asking about what might be causing a slight but noticeable vibration above 35mph most noticeable in 3rd gear when accelerating gently. Goes away if I shift into neutral and is better if I let off the gas.

Second problem is 4WD won't engage at all. Feels like maybe just mis-adjusted shifter. I may try the trunion adjustment myself but may just make the shop check it. The vibration worries me more with a big road trip coming up.

 

[RCP Phx]

First problem I think would engine/trans alingment.

 

[asymptonic]

Gonna have the shop take a look at it, but if they strike out, apart from it being annoying should I worry about driving it 900 miles at highway speeds?

 

[RCP Phx]

That would depend on you to determine how bad the vibes are? You didn't say what year but a lot of the tranny mounts have a small offset that's easily reversed.

 

[asymptonic]

Pretty minor vibes, but noticeable. (Edit: if the road is just a bit bumpy you can convince yourself it's that but it isn't). Jeep is a 1998, with a tranny mount that's only about 5 years old. It's a stock style mount.

 

[RCP Phx]

The '98 does have a 1/2" offset!

 

[asymptonic]

1/2" is a lot, I'd expect a ton of vibration if it were that. We'll see what they find, but I think I'd drive it. But now that I think about it I could totally see them botching that.

 

[lawsoncl]

The xfer case shifter may be assembled incorrectly or popped out. A lot of people replace the wonky oem setup with the Azzy or Boostwerks aftermarket version.