I got a random noise that sounds like Im hitting a rumble strip only times ten and its constant. I can get the noise to stop if I stop and then reaccaerate. It also stops if I put it into 4wd and nail the brakes for a second. If I leave it in 4wd it wont come back but it does if I switch bad to 2wd. It has done it to me anywhere from 15 to 65 mph
I have removed the rear axles they look fine. The spider gears look worn but you cant feel any wear. They have play but im gonna get feeler gauges tomorrow to check the play. The spider gears also seem noisier than what i remember. One should also know I had to replace the rear pinion seal a thousand miles or so ago.

 

Do you have the vacuum actuated axle disconnect in the front axle? If so it could be a failing/rusted thru vacuum motor.

 

yes i do. how do i check if its bad?

 

You need to check the vacuum being supplied to it and if the vacuum motor will hold vacuum when tested at both vacuum nipples on the motor. A hand held vacuum pump is the cheapest and easiest way to do this. If you don't have one you may be able to borrow one from one of the parts stores that loan tools if you don't want to buy one.

What rear end do you have? Did you properly torque the pinion nut when you replaced the seal? How did you remove/install the pinion yoke?

 

9 1/4
What is it sapposed to be torqued to? I didnt use any power tools to take it off or put it on.
I can fit a .020 feeler gauge beside the spider gears?

 

On the Chrysler rears like the 9 1/4 you are supposed to check the torque required to turn the pinion before disassembly. Mark the nut to pinion yoke and mark the yoke to pinion shaft so they can be put back in the same spot then remove the nut. To reassemble you realign the yoke to shaft marks and then retighten the nut until the nut to yoke marks line up. Then check the torque to turn the pinion. Continue to tighten the nut until the torque to turn the pinion exceeds the first torque reading taken before disassembly by 10 in-lbs with a torque on the nut of at least 210 ft-lbs.

Sounds complicated but it wasn't my design. Sorry.

 

I did not do the in lbs which I believe is called bearing preload. My torque wrench also doesn't go high enough but I torqued it as high as I could.

 

If you can't locate the noise problem you might want to change out the collapsible spacer on the inside of the rear on the pinion shaft. That whole procedure I posted is designed to prevent the over collapse of that spacer. For now you might want to check the ring and pinion gear contact and backlash. If those things are off they can cause a loud noise that will sound like what you describe. You can usually borrow the proper tools at the larger parts stores.

 

What I do about the bearing preload since that is obviously changed and incorrect? What about the fact that the noise does not come when its in 4wd? I would think if the problem is in the rear it would also come if it was in 4wd. I should probably also mention I just replaced the U joints on the front axle. I hope there wasn't a step there I missed that would cause this problem.

 

Are you sure you didn't knock one of the little roller bearings in the u-joint cup down into the bottom of the cup when you changed the u-joints. Did you change out the double u-joints in the constant velocity joint at the transfer case end of the front shaft?

When you give more info about what work was done different possibilities come to mind. I am just trying to think of anything that might make a noise arising from the stated work.