Alright this time ill type right and not call my differential a transfercase. Anyways, we took the cover off and all the gears look fine, but if the tires were not moving, then we would rotate them the gear area makes a clunk, we checked back lash and it was fine, the driveshaft is fine. Any ideas at all its really wierd we can not figure it out. Also the manual I have just says ad just the gear oil, but its limited slip so does it need an additive? TThanks

 

Ford friction modifier. One bottle.

 

thanks bud

 

There's a certain amount of play between the drive shaft and the tires. There's miniscule amounts in multiple areas, and they add up.

If you've measure the backlash and it's OK, then look further down the line. Look for wear in the spider gears and the axle splines. Grab the tire and give it a shake. YOu should not feel movement there. If you do, the bearings are worn.

Use the additive if you have a limited slip diff. Otherwise don't bother. It won't hurt anything, but won't help either.

 

When I grab the tire and shack it, i should not feel movement in the tires? Sorry just a little confused on what your saying there. Thanks a lot though

 

Yeah, it's like checking the ball joints in the front. Try and move the tire up and down, and front to back.

 

So sir, I did this and there was minimal play, barely any at all. Any place else I can check literally this does not make any sense everything looks so good. Its when I let off the gas and put on the gas I thought it was the gears hitting eachother but its not.

 

Then the problem may not be in the diff. Look for loose suspension parts, loose motor mounts, etc.

 

Did you remove driveshaft from vehicle to check? If no, remove as the driveline angle makes checking u joints almost a total guess.

 

Alright Bubba, so just take it off, and your saying check the you joints themselves right otherwise I was going to put the cover back on and fill it up again or should I just wait. It is back by the diff I can make it make the same noise it makes when I am engaging and deengaging the gas.