Bearing like grinding noise in 4h

When i put it in 4wd, it sounds like bearing is rubbing really bad....

Similar to when My hubs went bad.

I read a few threads about grinding, but its not that kind of grinding. It will work in 4wd, but make noise.

I have yet to look at it really, but I am going to check the fluids first, then check the linkage. I read a little thing about how to adjust it, but still unsure.


BTW, its an 01 cherokee.

Most important, what transfercase do you have? Transmission?
Have you checked the t-case fluid for metal shavings?

I think the 231.... I've yet to dive in, as I just drove the others. But I use this a lot for work

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Make sure your tires are evenly worn and evenly inflated. It will get pretty noisy if they're not.

Matthew Currie said:

Make sure your tires are evenly worn and evenly inflated. It will get pretty noisy if they're not.

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Checked that, and they are all very even.

could be the chain dragging on the case

could also be the front axle u-joints or ball-joints, they are loaded differently in 2WD (coast) and 4WD (drive)

a few other possibilities too but those are the most likely

I am leaning more toward its something in the front end. I have some axles with new u-joints in the attic I am going to toss in.

Hey guys,

thougt i would resurrect this one, before i start a new threat...

I've got the same issue with my 94' XJ. Specs are: 4l, AX-15, NP231, D30/35. Lifted about 4,5" and running 33s or 31s depending on season. The 231 is equipped with an Advanced Adapters SYE Kit.

So when i put it in 4 HI yesterday, because we already have snow over here, there was a humming noise from somewhere in the middle or front of the car. It gets louder / sounds meaner when accelerating. In 2 HI there is no noise from the driveline at all. It switches perfectly between 2 HI and 4 HI btw.

Here is what i already did:

- Checked fluid level of TC and Gearbox: Fluid level is perfect...fluid is clear and smells like new.
- Checked the flanges of TC and front axle for any play and turned them by hand to maybe feel any bearing grinding or strange drag. Everything was tight and no noise or drag when turning by hand. (Didn't turn the flange of the front axle yet btw)
- Removed the front drive shaft and drove around. Put it in 4 HI without front DS...no noise at all. Even put it in 4 LO without front DS...no Sound, besides the usual "reduction whining".

U-Joints and CV Joint in the front driveshaft are maybe half a year old.
Did the SYE Conversion maybe 2 years ago...TC looked like new on the inside. All the bearings, sprockets and the chain seemed to be in perfect condition. Of course i did some wheelin' in the meantime, but not often and (i think) moderate.

How can i find out if it is the TC itself or maybe the front axle? Got another driveshaft in the shop...i will test this asap.

You guys got any ideas on how to figure it out and what could possibly cause the problem?

KingIce said:

Hey guys,
How can i find out if it is the TC itself or maybe the front axle? Got another driveshaft in the shop...i will test this asap.

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You can disconnect the front driveshaft, if it still makes noise then its the t-case.

T-case usually whine in 4 low, due to reduction gears not getting a lot of usage. If it's just a whine I wouldn't worry about it.

Removed the front drive shaft and drove around. Put it in 4 HI without front DS...no noise at all.

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Already did that...but I'm not sure if noise caused by a bearing or something inside the TC only appears when there is force on it. With removed driveshaft things can spin freely and maybe don't make any noise at all. This would lead me in a wrong direction.

Otherwise, when the 4 HI gear components are damaged, they are damaged, so it should be noisey as soon as 4 HI is engaged...irrespective of the driveshaft being there or not.

What do you think?

Even a tiny difference in tire diameters can make for extra noise, even if it's too slight to affect shifting. According to the manuals, some time in 1995 they dropped the synchromesh from the NP 231 case. It was necessary with the disconnect axle, I think, in case the axle did not get up to speed in time. This may make it harder to get into 4WD when wheel diameters are way off or other problems exist, but it also reduces the tendency to stay in 4WD when you shift out, which was common in older ones when the driveline was a bit stressed. Have you played with tire pressures?

First thing I'd do after a diameter check is check fluid, and make sure the linkage is adjusted and free. If you haven't done the maintenance yourself, don't count on a former owner having used the right fluid. It takes Dexron, but some people throw in gear oil. If your linkage is stiff it may not be allowing the case shifter to snap into place, so make sure it moves freely.

Thanks for your reply!

The tires are evenly worn and tire pressure should be exactly the same in all 4. Since i didn't know that this can be an issue, i will double check it.
I haven't tried different tire pressures yet...will do that next.

I did the maintenance myself, so i can exclude wrong fluid or a low fluid level. Shift linkage should be adjusted well...shifting between the modes is easy and everything works fine.

And because of this

Did the SYE Conversion maybe 2 years ago...TC looked like new on the inside. All the bearings, sprockets and the chain seemed to be in perfect condition. Of course i did some wheelin' in the meantime, but not often and (i think) moderate.

Click to expand...

i just don't believe that the TC is somehow damaged. I mean it's a sturdy unit...it just wouldn't destroy itself magically wouldn't it?