what can make the front differential lock up on a 96 jeep grand cherokee all wheel drive?
Define "lock up" did the front diff lock into full 4WD or did it seize up completely. Either way you are still going to tear into it to find the trouble. If you kept the tire diameter the same as stock it should not have caused a problem changing wheel size unless you did something crazy with the width.
No, I just put 20 inch chrome rims on it.
So it looks like you will have to tear into the front end to find out what let go or just go to a wrecking yard and get one with the same gear ratio and with AWD, pull off the cover and inspect it for and problems, clean it out good and refill it with new gear lube and the special fluid from Jeep for AWD's and just swap it out.
viscous coupler in transfercase is locked up. it should transmit power to ft. axle like a posi unit in rear end. They do have a tendancy to go bad and lock up. Vehc. will buck and grunt when turning. You can replace it without removing t-case. But just be sure to get oil pickup tube back into the pump.You will prob. crap when you price the part. prob. cheaper to locate a good used one.
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