Clegalley

I'm stumped, mechanics stumped. I have a 98 with a 3.5 inch lift, completely rebuilt fresh diffs and driveshafts. I have a whine in 2wd that gets higher pitched as I accelerate (almost like tire noise), in 4hi or 4ft (I have the 242) it makes a grinding wirling noise under load, sounds like a bearing. When I take the front shaft off and drive it in 2wd or 4hi there is no noise. I cracked the T case and replaced the front output bearing and the needle bearings as recommended by a technician that specializes in T cases....no I didn't rebuild the entire case I was just trying to localize it and only take the back half off. The fluid was completely topped off and it was perfect bright red when I drained it, no shavings or debris and everything looked great in the case. I'm at a loss. Could it be the front pinion angle?

tech

They make a tool that helps with finding noise . It has a bunch of microphones that clip to different parts parts to see what is making noise . You just put them on and go for a drive and see where the noise is .

Battle

If you removed your front driveshaft and the noise went away, you may need to rebuild the front driveshaft. The cardan joint/other u-joints could be trashed.

Clegalley

The front shaft was completely rebuilt by a shop.

Battle

Dang. I wish I had more experience with the NP242 to help. Maybe it's the center diff?

I've never really thought about the front pinion angle before like you typically would for the rear, but that could be it. Do you have the ability to adjust caster, i.e. adjustable control arms?

EZEARL

I'd be checking the pinion angle if nothing more than to eliminate the possibility.

Clegalley

I actually just got some adjustable uppers that I’m installing tonight just to cross the pinion angle off the list.