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noisy np242 troubleshooting - tire size ?

Ilikeparts

NAXJA Forum User
howdy fellas, been a while..

this may have been covered already I did a bunch of searches and found a lot of conflicting opinions and no direct answers to my question, so here goes..

Im an XJ guy but im fixing a buddies 96 ZJ 4.0 with the 242 case. before you guys delete my thread and kick my a$$ over to mallcrawlin.com, these cases are identical to the XJ, right? so this should be good XJ tech too :)

this truck is a stocker is really only used in 2wd. has a growl and floorboard vibration mostly under acceleration at lower speeds, coming from the middle/rear of the truck. the front axle is in bad shape, but the noise is not coming from the front. the rear axle is a 'good' used m35 (i live in mexico). i jacked it up and dropped the driveshafts(they seem good), rear pinion yoke seems to have little to no pre-load but operates smoothly with no end-play, wheel bearings seem good - the m35 could probably use a re-bearing but im pretty sure the growl is coming from the transfer.

with the driveshafts dropped and the tranny in neutral, the front output yoke has smooth operation with no wierd noises. the rear yoke however, doesnt have any slop but when turned makes the chain slop noise and also a sort of high-pitched squeaking.

this guy has a different sized set of tires in back than he does up front. ive rebuilt a couple 231's, but never a 242. I know for the 249 this is a no-no, but my question is this :

with a 242 case and different sized tires, will running 2wd on the street (long-term) cause damage to the differential? does this seem like a good diagnosis ? case was full on fluid btw. is there anything else i can do before i tear it apart? transfer parts are a PITA to find down here and im not taking it apart until i have a rebuild kit. do it once do it right :) thanks!!!
 
in 2wd the different tire sizes wont matter. the 242 isnt THAT different from the 231. rebuilding it is fairly easy. which is what it sounds like it needs to me. does the 4wd work as normal?
 
yah the 2wd, 4wd FT, 4wd PT & 4wd lo all shift normally.

yah i suspect i will be doing a rebuild on it as well, the chain slop noise and squeaking when i spin the mainshaft is the biggest thing that jumped out during diagnosis. anything else i can do to verify ? run it with all four in the air ?
 
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