The inboard CV joint was toasted. When I went to pull the axle from the trans the dam thing cameapart!
Yet the boot and band were still perfectly in tact?

So I popped the new (passenger side) axle in& now when I ramp it up in second gear, around 6100 RPM, I hear/ feel thumping on the floor board.

Could my differential be jacked up, like a is shot bearing or something

 

Inboards can slide out of the housing, I do believe, if you pull on the shaft. And as for the noise, it could still be a bad inner joint. Driving in a straight line a vibration is usually an inner joint, clicking on turns is usually the outer. Had a VW GTI that shook the dash on a 3,000 mile trip because of a bad inner CV joint - not enough grease and had groove worn into the housing.

 

Thanks for the quick response! The only thing is that I put a brand new axle shaft in. The car has no noise until over 6000 RPM in 2nd gear. Imagine pounding your fist on floor board ever second, that is the noise I am hearing, & I can feel it to.

 

check your lower motor mount

 

I saw the "new" and most are pretty good quality, but if you actually meant a "new" rebuilt axle then it still wouldn't surprise me if the rebuilt axle was bad. I install axles where I work and sometimes it seems like every other rebuilt one is bad. Last Subaru I worked on took 3 rebuilts before I found one good enough to get the car off the hoist. Aside from an axle problem, I'd check the mounts real close - or like you first suggested, I've seen differential bearings cause a vibration.

 

Looks like the expert has arrived. I'm still not too familiar with Neons or turbo-anything, but I'll try to help if I can.

 

your advice is very good, i was just suggesting another thing to look at with the thumping. very often the lower mount gets loose, especially after breaking an axle, and bumps against the oil pan. if its not the axle itself that's causing the noise than it could be a mount. just suggesting other things to check

 

Thanks you guys! The loose or broken motor mount makes sense.