rattle/grinding noise in transfer case

[Vinni]

Got a problem SD Gurus,

I had the 12" lift done on my 00 X with 41" tires orriginally (loaner wheels and tires). yesterday i had the Irok 39.5" tires and 20" wheels put on. all of the sudden i have a grinding/rattle sound comming from the transfer case. It sounds (from inside) just like when my 2wd had a bad u-joint when the throttle was neither pushing or decellerating the vehicle due to motor force and also when the rear penion was loose. I can get under the truck and hit the side of the rear drive shaft and i here a knocking sound ont he far left of the transfer case.

Could this be possible due to the pinion angle from the lift and i need a wedge put in ont he rear end to pitch the pinion angle? Could the pinion in the transfer case be loose or riding funny ont he gearing within the transfer case?

Any help you might be able to get me would be great...

 

[DaveBen]

I can't tell from your description, but the pimion angle for the transfer case and the rear end should be the same. If not you can get the "coasting" noise you describe.

Dave

 

[Vinni]

With the lift, how do you get the pinion angles to match up on each end to get rid of the pinion's "coasting" noise?

 

[DaveBen]

The theory is that they should be parallel to each other. If your pinion angle is +2°, then your transfer case output shaft should be +2°. If one is way off compared to the other, that maybe your problem. You usually shim the rearend to match the transfer case. Most four wheel drive shops have wedges.

Dave

 

[Vinni]

Update

It seems that due to the lift ont he truck - the noise was due to the angle of the drive shaft beyond the transfer case. To fix the problem, the transmission crossmemeber and skid plates were both lowered 1 1/2" to alleviate the u-joint at the transfer case.

Now the truck runs great with no lashing sound.

Thanks for your inputs...