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90xj06
October 12th, 2017, 11:10
so im on the hunt for finding drive train noise.

currently i have replaced the wheel joints and rear drive shaft joints. (Replaced because i didn't know the condition and could not grease them + front ones are toast.)

noise still seems to be there. it also seems to have a peak noise at 35mph. and then it doesn't get much louder after that. but road noise might muffle it.

it has the np242 which i changed out the input gear on but did not rebuild it. its hard to tell where the noise is coming from.

i still have the vacuum controlled front axle but had set the shift fork to lock it all the time. i recently unlocked it to check if it was the front driveshaft or output on the transfer case.

noise is still there if coasting in neutral.

im going to be swapping out the front wheel hubs also. not sure if i should check anything else while im down there.

1988 Cherokee 4.0 NP242

trippled
October 12th, 2017, 12:38
Diff bearing?

90xj06
October 12th, 2017, 12:41
how hard is it to do a diff bearing?

mfascuba
October 12th, 2017, 17:16
I had a noise like that. I replaced all 7 u-joints, both unit bearings, had new carrier bearings & shaft seals installed on front & rear axles along with new pinion bearings, crush sleeves & seals and gear contact/lash set up, and replaced my np242 with a NOS unit. Still had the noise. Called it good & turned up the radio.

90xj06
October 12th, 2017, 17:37
I ignored it for about a year. It's getting worse now. I'm going to attempt to lift the Jeep and see where the noise is coming from.

JeepNoob
October 12th, 2017, 18:02
how hard is it to do a diff bearing?

If he's talking about the bearings the axleshafts ride on, challenging, but do-able for a DIYer. Pinion bearings are a whole other can of worms..

trippled
October 12th, 2017, 18:26
Yea I'm thinking a carrier bearing. It must be pressed on and off. They're not too bad for a really competent do it yourself, but yes pinion bearings require more know how. And usually if a carrier bearing is bad the pinion bearings aren't far behind.

What kind of noise is it? Does it change if you turn left to right? Low rumble, grind or chirp?

Anak
October 12th, 2017, 20:02
I am on the hunt for a drivetrain noise too.

Both axles have been gone through, all the way to pulling out the carriers and checking all bearings.

I swapped tires just to eliminate that variable.

Next step is T-case. I am thinking it may be the range fork. Probably tear into the case this weekend.

mfascuba
October 12th, 2017, 20:39
I am on the hunt for a drivetrain noise too.

Both axles have been gone through, all the way to pulling out the carriers and checking all bearings.

I swapped tires just to eliminate that variable.

Next step is T-case. I am thinking it may be the range fork. Probably tear into the case this weekend.

Which case are you running? I saved my 242, just picked up a 2WD that Iím converting to 4wd. Got a transmission on the way and I found a 1996 high pinion D30 in the junkyard that Iím going to pull this weekend if itís still there. My 242 had about 130,000 miles on it, I had just put a new chain in it.

Anak
October 12th, 2017, 21:57
NP231.

I am doing an SYE conversion along with the overhaul.

I think I have all the pieces. Even a new range fork since that is my number one suspect.

90xj06
October 14th, 2017, 08:27
My noise does not seem to change with turning. It's more of a low rumble being the loudest at 35. Does not seem to change when switching from accelerating to coasting. And I can almost feel it in the floor. Could the speedometer cable do this? It's pretty jumpy until it hits 35. And it's rubbing on the floor.

Anak
October 14th, 2017, 08:45
That is an interesting thought.

It should be easy enough to disconnect it from the T-case, zip tie it out of the way and go for a spin around the block.

While you are at it, might be a good idea to lubricate that cable. I am guessing you haven't done so, and probably no one else has either. I think graphite is the best way to go, and you should probably work from the top end for that purpose.

90xj06
October 14th, 2017, 14:39
it was not the speedometer cable. infact the cable itself was in great shape and spun very easily. i wonder if the short cable from the speed sensor or the cluster itself needs lube.

i think i did narrow it down to the T-Case. https://photos.app.goo.gl/J8wgclJRxYiDmINd2

it makes that rattling noise in every gear but neutral. i really dont want to have to pull this again.

90xj06
October 17th, 2017, 07:24
So the noise seemed to have gotten worse. I recently changed diff fluid but I didn't give it a great lookover. But there was no shavings and the teeth looked good. Is there a way to check the carrier bearings by just spinning the wheel? I'm going to attempt to get all 4 wheels off the ground so I can look for the sound. But one of my jack stands seemed to have walked away.

90xj06
October 18th, 2017, 06:50
Can someone confirm this for me.
1.) when the front axle disconnect is not engaged the carrier does not spin? just the spider gears?

2.) the axle shafts do not have bearings on them except on the wheel side?

3.) the intermediate shaft has a bearing in the shift fork housing on the drivers side. and just a seal on the passengers side?

so theoretically if a bearing noise is not coming from a wheel bearing while the shift fork is disengaged then the only other source for noise would be that bearing at the shift fork. thus eliminating the carrier bearings and pinion bearing. for sources of noise?

just trying to logically narrow down the sources of my noise before i go digging around and make it worse.

Green XJ Jeep
October 18th, 2017, 07:33
Are you sure the noise is even coming from the front and not a bad trans mount or something else related to the r&r of the tcase?

mfascuba
October 18th, 2017, 07:34
The carrier will spin, because the axle from the drivers side will turn it. The axles are supported by the carrier (bearings) on the inside, and the hub unit bearings on the outboard sides. The disconnect has a bearing on the inboard side supporting the axle going to the carrier, and a seal on the outboard side that the axle shaft from the wheel hub goes through. When it's disconnected the inner shaft on the disconnect side will be spinning at the same speed as the carrier, with both carrier bearings and the disconnect bearing all moving.

90xj06
October 18th, 2017, 08:15
Are you sure the noise is even coming from the front and not a bad trans mount or something else related to the r&r of the tcase?

the noise sounds like its coming from the front. the trans mount is new. along with engine mounts and upper and lower control arms, shocks, swaybar bushings and links.

i ordered a rebuild kit for the transfer case but i dont want to have to deal with that unless im 100% sure its it that.

The carrier will spin, because the axle from the drivers side will turn it. The axles are supported by the carrier (bearings) on the inside, and the hub unit bearings on the outboard sides. The disconnect has a bearing on the inboard side supporting the axle going to the carrier, and a seal on the outboard side that the axle shaft from the wheel hub goes through. When it's disconnected the inner shaft on the disconnect side will be spinning at the same speed as the carrier, with both carrier bearings and the disconnect bearing all moving.

so even with the drive shaft not spinning the carrier still spins? well at least the bearings do?

i figured the spider gears would just rotate and cause the intermediate shaft to spin in the reverse direction.

Anak
October 18th, 2017, 08:24
I do not think the spider gears would be happy if they had to spin at a rate to keep up with tire rotation.

mfascuba
October 18th, 2017, 08:57
Let me think this through - Driver side axle shaft is going wheel speed, passenger is disconnected. Carrier has spider gears, so yes, the spider gears will move and the carrier should be more or less stationary if the driveshaft is stationary and the vehicle is moving. Have you pulled the front driveshaft & seen if the noise is still there? I had a wobbly driveshaft once, pulled it and everything smoothed out nicely. You may have a bad U-joint in the front shaft. There are three of them, cheap fix. Free for the time being if you just pull the shaft out and the noise stops.

md21722
October 18th, 2017, 09:03
The carrier bearings always spin as long as the driveshaft or wheels are turning. Carrier bearings typically make noise under all road conditions as low as 10-20 MPH. To isolate the noise you can run the car on a lift or jack stands. Put your ear to it. Doing carrier bearings properly is not for the unmotivated. For D30/D35, if you are lucky you can take the old bearings off and press new ones on. However, variances in bearing thickness, etc. still may require measuring shims and reshimming. 8.25 requires tools for the side adjusters, setting backlash, etc. By the time you have to deal with all of this, it can be easier to get another good axle from the junk yard.

90xj06
October 18th, 2017, 09:06
i did pull the shaft and there was noise. not sure if it was the same noise. however the shift fork was locked at that time the drive shaft was removed. i will remove it when i get home today.

i wonder if the shaft is spinning slowly while the fork is unlocked.

im wondering if there are 2 noises now also. originally i was looking for a faint noise. then this came up. and i assume it was the same noise.

90xj06
October 18th, 2017, 09:09
The carrier bearings always spin as long as the driveshaft or wheels are turning. Carrier bearings typically make noise under all road conditions as low as 10-20 MPH. To isolate the noise you can run the car on a lift or jack stands. Put your ear to it. Doing carrier bearings properly is not for the unmotivated. For D30/D35, if you are lucky you can take the old bearings off and press new ones on. However, variances in bearing thickness, etc. still may require measuring shims and reshimming. 8.25 requires tools for the side adjusters, setting backlash, etc. By the time you have to deal with all of this, it can be easier to get another good axle from the junk yard.

i have a spare front axle. but the spring seats are all rotted. i was thinking of grabbing one at the junkyard but i would have liked to keep the center disconnect. and put a posi lock in it. but u suppose i don't need to have that.

Green XJ Jeep
October 18th, 2017, 13:42
Let me think this through - Driver side axle shaft is going wheel speed, passenger is disconnected. Carrier has spider gears, so yes, the spider gears will move and the carrier should be more or less stationary if the driveshaft is stationary and the vehicle is moving. Have you pulled the front driveshaft & seen if the noise is still there? I had a wobbly driveshaft once, pulled it and everything smoothed out nicely. You may have a bad U-joint in the front shaft. There are three of them, cheap fix. Free for the time being if you just pull the shaft out and the noise stops.
Correct which is why driveshafts on disconnect front ends were horribly balanced from the factory. They dont spin all the time so need need for spot on balancing.

Green XJ Jeep
October 18th, 2017, 13:49
i have a spare front axle. but the spring seats are all rotted. i was thinking of grabbing one at the junkyard but i would have liked to keep the center disconnect. and put a posi lock in it. but u suppose i don't need to have that.
This isnt as finnicky as a posi lock
http://www.wranglerforum.com/f290/4wd-to-2wd-integrated-vacuum-switch-76453.html#/topics/76453?page=1

90xj06
October 19th, 2017, 09:13
i pulled the driveshaft and the noise is still there. and the vacuum actuator was bad. i ordered a posi lock but i must have ordered the one for a 3-6in lift.

the noise seems to stay a constant speed but sounds like it goes away if bumps are hit and the jeep is bouncing up. it sounds slightly jingly sounding like a bell sometimes.

90xj06
October 19th, 2017, 16:06
i had time to get the rear end up on jackstands today. rear end seemed to make no noise but the passengers side rear brake was dragging a bit. even with the tcase in 4wd part with no front shaft i could not hear any noise.

so im hoping its just that bearing on the intermediate shaft as it should not be that bad to fix. i could slightly feel a vibration equal to the noise in the steering wheel also which is why i really think its from the front end.

it also does not help that one of my tires is out of balanced and cupped along with a mild toe out. im wondering if i shook the bearing to bits lol.

lawsoncl
October 19th, 2017, 19:39
i had time to get the rear end up on jackstands today. rear end seemed to make no noise but the passengers side rear brake was dragging a bit. even with the tcase in 4wd part with no front shaft i could not hear any noise.

so im hoping its just that bearing on the intermediate shaft as it should not be that bad to fix. i could slightly feel a vibration equal to the noise in the steering wheel also which is why i really think its from the front end.

it also does not help that one of my tires is out of balanced and cupped along with a mild toe out. im wondering if i shook the bearing to bits lol.

Or the cupping is due to a bad bearing? No noise in the air would tend to point to a bad wheel bearing.

90xj06
October 20th, 2017, 07:28
i checked the bearings. seem tight and smooth. i will replace them anyhow. also im not 100% sure that the cupping is from this jeep. the tires are from my other jeep.

im going to attempt to remove the rear driveshaft and run it with the front axle up in the air. and hopefully find the noise.

90xj06
October 22nd, 2017, 16:58
so... it may have been wheel bearings. noise seems to have gone away.

i still have my transfercase noise but that can wait until the spring.

cwyman6
October 23rd, 2017, 19:16
Was tge transfercase input gears compatible? There are two different gear cuts and if you mix match it will make the noise you are describing. Check novaks website for the year cutoff between old and new style.

RCP Phx
October 23rd, 2017, 20:48
Was tge transfercase input gears compatible? There are two different gear cuts and if you mix match it will make the noise you are describing. Check novaks website for the year cutoff between old and new style.

They are not even interchangeable!

90xj06
October 24th, 2017, 06:39
the np242 transfer-case was a 92 which claims it was compatible with the 88's input gear.

it looks like until 95ish it was the same cut.