Hi there,

Just got a 1992 Jeep XJ, and have noticed a strange (and disturbing) problem.

Every now and then, when I take the jeep out of park and put it in drive or reverse, sometimes the car will roll about 4 feet then lock up like I hit a brick wall. If I get enough speed, the tires will chirp, it is that dramatic. The only way to move the car past this point is to put it in park, reverse, drive, and move the car in these modes repeatedly until it 'gets past' the point that it locks up. Sometimes, the whole car will shutter with a 'buh-bang' when it gets past the point of lock up, other times it just rolls right past it.

When it does happen, I notice a faint 'thunk thunk thunk' coming from the rear of the vehicle as it is rolling, and is proportional to speed of the vehicle. Applying brakes does not change the noise or make it go away. The thunking noise happens in forward and reverse, and in neutral when it is apparent. Other times, it works just fine like there is no problem.

Do I have pieces of gears floating around in my diff? If so, why does it only lock up when I go from park to driving (i.e. why does it not happen all the time, even when driving)

Thanks!

Ryan

Easiest thing I can suggest is to pull the rear diff cover and take a look,

Busted spider gears will do that. Hope it's them - lot cheaper to fix yourself.

The weird thing is, it only does it when I go from park to drive, it never locks up when I am driving (Thank God!), even though I am pretty nervous about this happening on the freeway. The other thing is, there is no noise when I go around in circles (wouldn't busted gears make noise doing that?)

Will probably tear into rear diff this weekend,, got replacement gear oil ready to go...

Thanks,

Ryan

What part of town do you live in, Ryan?

@Avis - I live in Corona

So here's some fun news. It was the diff. When I got into one of those 'locking' episodes, I put it in 4 low, and muscled through it, only to hear a loud 'bang', then the RPM's were obviously going through the gears when I pushed on the gas, but the car would not move. So, I got out to look, and sure enough, the driveshaft was rotating, but the wheels were not. SO.... I put it in 4 high and drove her home in front wheel drive mode. I then put it in reverse to back it into my garage to work on the diff, only to have it lock up again. Frustrated, I put it into 4 low again and hit the gas, and this is what happened:
Making a nice grease mess on my driveway and the street in front of my house.

Needless to say the diff is worthless now. So, I got another one, a Chrysler 8.25. Hopefully it has the same gear ratio as the front, I think it is 3.55 (?) , as it has a metal tag on it that says 5.5.

So here's the question, my old axle has ABS, at least that's what it looks like to me, a magnetic sensor with a splined shaft that rotates under it. No such thing on the new diff. Can I disable ABS on the whole car ? I don't care about ABS as I don't think I could lock up the tires even if I pushed super hard on the breaks.

Any help would be super appreciated!? Thanks.

Lol that picture cracks me up.


Easiest way to check gear ratio is to count the teeth on both, or at least where the teeth should be on the old one and if its the same, your good to go. As far as ABS goes... You don't have to hook it up, but you'll have an ABS light that will never go away.