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mismatched gears?

89jeepxj

NAXJA Forum User
Location
Mountain View
alright, so ive got an 89 with an NP231 t-case. Im swaping in a chrysler 8.25 in the rear with 3.55s. Ive got 3.07s in the front and i just wanted to make sure that driving with mismatched gears for a while, till i get more money, would be alright as long as i dont shift into 4hi or 4lo. thanks for ur help
 
It should be fine, but also do not put the tcase in neutral when the vehicle is moving. Neutral on an NP-231 connects the front and rear shafts together, but disengages if from the tranny.
 
Pulling the front drive shaft would be cheap insurance to make sure that you don't damage anything by accidently shifting into 4 wheel. Just a thought.
 
As long as you dont put it in 4 your fine, i did that once wwhen i had 4.88 in the rear until i set up the front. Lest just say 4.10 and 4.88 dont play well together. Luckily i did it from a dead stop to get over the snow in my driveway. I had a friend who accidentally once did it in the snow while doing about 40 somre mph and everything grenaded. Put a piece of duct tape or something on the shift lever to remind you if you are a burn out like i was. Oh and i had no damage but the jeep was shake rattle and rlooing like u wouldnt believe and i just kept shifting the lever until it popped out.
 
I second nhrocker. Just pull the front driveshaft to avoid any possible mental lapses.
 
Eagle said:
I second nhrocker. Just pull the front driveshaft to avoid any possible mental lapses.


Exactly what they have said, pull the front shaft. That way if you accidently shift into 4lo you can have fun with smoking the rear tires only :D

AARON
 
MrShoeBoy said:
Exactly what they have said, pull the front shaft. That way if you accidently shift into 4lo you can have fun with smoking the rear tires only :D

AARON
I have no problem smokking mine in 2HI but anyway One of my friends gota a blazer that had little tires up frt. just to pass inspection (the sad part is he did) but he was dumb enough to put it in 4wd and it was the worst sound i have ever heard.
 
Since you have a '89 231, you probably also have a disconnect D30. Just pull the vacuum connector off the disconnect mechanism. The gearing difference, if you do shift into 4wd, will be taken up in the spider gears of the front differential since the passenger wheel will not be connected. Ran my '87 MJ with a 3.55 D44 and 3.07 D30 for awhile and occasionally needed low range for moving heavy loads & trailers. No problemo.
 
I know that the drive shafts are different lenths but I'm not sure about the ujoints.
 
nhrocker said:
Pulling the front drive shaft would be cheap insurance to make sure that you don't damage anything by accidently shifting into 4 wheel. Just a thought.
3rd that

though DEEP SLUSH mud that you get stuck in in 2wd would suck...
and 4x4 could be used here - just the front axle would spin more than the back...

nvm, pull the front shaft...

and the ujoints are the 1310 u-joints IIRC in both pinion yokes - so you should be ok.
 
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