jjz28

My jeep rolls when I give or let off throttle. I got under it and tried wiggling the driveshafts. The front one was solid but the rear one, I can actually make the transmission move side to side a little. I cant see any broken mounts but maybe the bushings are worn out? Also my front seal where the drive shaft goes into the front diff is leaking and also making noise. It only make the noise when I am applying throttle above like 30mph. I think it may be the bearing in there, don't know what it is called maybe pilot bearing? I hope the gears aren't messed up. How hard is that bearing to replace? My jeep is a 96 grand Cherokee, 318 engine. thanks.

dave1123

Yah, that's called the pinion gear and it has 2 bearings on it that are a PITA to replace. NOT for the uninitiated. Proper bearing preload must be set and gear lash must be adjusted.

If the transmission moves side to side, chances are the mount is broken. There's a rubber donut that fails, but it's held inside a steel ring so it won't break something else. It will mess up your shift linkage though.

jjz28

Thanks dave. Do you think that would cause the jeep to pitch when giving and letting off gas? Its like when you rev and engine and the engine moves, that's what it does but I don't have broke motor mounts or and sway bars broke.

dave1123

I hate to think about this, but my 97 started pulling to the right on mild acceleration and returning to straight when you let off. This was because the left lower control arm in the rear was broken at the frame mount. Check your undercarriage closely.

The motor mounts are also bushings in rings. They are called "safety mounts" designed to contain the engine if they break. Again, they are a round bushing in a steel ring and when they fail, it's not always obvious from looking at them. Hold the brake with somebody watching the engine and shift to drive and reverse adding a little torque. If the engine twists more than a little, chances are they are broken. That 4.0 weighs about 500 lbs and it can change the jeep's direction if it moves.