hey i have an 87 cherokee and i recently had the crappy peugot tranny changed out for an ax15 with an np231 transfer case and ever since then i have been experiencing an intermittent grinding noise that sounds very similiar to missing a gear and getting your trans. to grind. i know now that it is not the tranny, it shifts like butter every time and stays in gear so its not the syncros, the vacuum lines are good on the x-fer case (or so i think cause the 4wd still works flawlessly), and i fixed the vacuum lines on the stock dana 30 split axle so its not that. my only remaining idea would be that maybee when they changed the transmission, they used the same starter and maybee the starter is hitting the flywheel under stress?!?!? PLEASE HELP!!! if anyone has been having anything like this, any advice is much appreciated!

 

just because it stays in gear doesnt mean the syncro's are good, it could also have a bent shiftfork. i guess it would help if you told us when i made the noise. is it during a shift, is it just at any random time, does it only do it in certain gears?

 

i experience the noise randomly in almost every gear. sometimes it does it for a tenth of a second when i go over a bump in the road and most of the time its when the jeep is in 1-3 gear and the motor is under stress. when it starts doing it, i can get it to stop or start doing it again by changing RPM's of the motor which is why i want to think that its vacuum related. like maybee something is trying to engage? thats why i checked the front vacuum shift motor assem. and all the vacuum lines from the transfercase

 

oh and i forgot to mention it does like to make the noise for about a tenth of a second in intervals while going up a hill as well

 

so i just got done pulling the starter to see if it was the source of the problem. what i found was rather interesting, the teeth on the starter and the flywheel were damaged in one direction hinting at a moving collision. is there such a thing as a starter shim? or maybee a starter gasket lol???
i dont know if you all can see these but i took pictures so you could give me second opinions: (first one is the starter teeth, second is the flywheel teeth)


http://img18.imageshack.us/i/1000223x.jpg/

http://img20.imageshack.us/i/1000224b.jpg/