I have a 2000 jeep cherokee sport 4x4 .. During hard acceleration I can feel a vibration between 30 and 40 mph .. Could this be u joints or does the rear differential need new pinion bearings?

 

First guess would be Ujoints. Pull your drive shafts and see if they are binding up at all. Also, check your motor mounts and tranny mount. If you see any up & down or side to side play in your pinion, then that would be a bad pinion bearing, but start with the ujoints and mounts first, and you may also want to rotate your tires and see if the vibration changes at all, which would indicate a tire balance problem.

 

When I had this same issue, it was the tranny mount. It had collapsed. Could be about anything though.

 

Need some more info.. Lift, tires etc.

 

No lift stock tires

 

It could be quite a few different things he is correct, your just going to have to work through them starting with the mounts engine/trans. These are easy to check just have someone in the car and you look under it at the mounts while in drive with the brake & parking brake applied. Then give it a little gas and see it the engine or trans lifts up any then you will know about those 2.

 

Here's how to find out:

The only way you're gonna find what you're looking for is to GO LOOK!

Around the Jeep that is. In these parts, we call it "noggin pokin".

That's where you use your God given senses to inspect YOUR Jeep for problems. We can only provide you with guidance as to where to poke your noggin.

There's no Silver Bullet cure you're gonna find from a keyboard, mouse and monitor.

 

Are the rear springs like marshmallows?

 

I actually just replaced them .. It has 200000 miles on it .. I've pretty much pin pointed it to the u joints .. They have a lot of play

 

You mean "toasted"?

 

yep.

Is it dog tracking?