front drive shaft transmitting noise?? pulled it & swapped it.

01XJ, LP D30, 4.11, truetrac

had my gears done last year or so, never had a problem, broke them in,pinion is set at 1°, swap my diff oils every time i get this thing in the water, everything has been going great untill just recently.

i developed a strange wheel speed"ish" kinda grumble. if everything is quiet you can hear it best while rolling to a stop.

i found that i had some wear in my slip joint on my front shaft, pulled the shaft, sounds are gone. picked up a used shaft that i pulled out of 99xj that looks like its been in dry storage for 20 years. yes its not new, but its tight and spotless..its still used though so who knows.

i install the new shaft and the jeep runs way smoother, a huge portion of the noise is gone but i can still hear something going on..

my last diff lube change i had some silverish oil going on up front, it was magnetic but was so fine you could not actually feel it in your fingers, but the magnet showed it was there..i have always had a fine shine in the oil but this time it was pretty dark compared to my rear oil that was swapped at the same time and also runs a true trac

has anyone on here found that the driveshaft will transmit gear or U joint noise that you could not hear otherwise when the drive shaft is pulled?

im going to get some new unit bearings and u joints again, pull my diff cover again and see if i can find any movment now that its been another few weeks of driving, but everything was tight last time i checked two weeks ago.

i could possibly have a bad drivers side u joint, its a fresh joint and the movment in it is almost un noticable compared to other bad u joints i have had, but there does apear to be a few thou or so of rock in the one axle. altho it makes no noise when the drive shaft is pulled so...

opinions welcome

I would check on the u-joints and unit bearings.
If you are unsure of when the unit bearings were replaced last, good to change them. I'm running some ebay cheapies and seem to be doing fine.

unit bearings were changed years ago, i have the bill but it was long before i bought the jeep. turns out ya cant just go buy high quality unit bearings in my area, i can get "good" bearings but damn near double the cost of ordering some timkens online...

but yes i will swap them out. the plan is to build a complete set of new front shafts and keep these as get ya home in a pinch spares.

i have had unit bearing failure in the past but it was more along the lines of...everything is going good, ohh $h!t boom there goes a unit bearing..

i will swap it out and report back

thanks

went to work on the truck today,
turns out my unit bearings had about 5 ftlbs of torque on them. I pulled the bearings, one felt great and another I could get a little noise out of, swapped them out for some fresh SKF bearings.
while I was in there I did my axle U joints, they were toast...
pulled the front diff cover, found some more metal dust in the bottom of the diff but no signs of unusual wear, ring and pinion look great, took the pry bar to the trutrac to see if I could get any movement out of the bearings, mind you I did not have a dial on anything but I could not see or feel any movement.. rotated the tires and greased everything

slapped it all back together, rolled it out on the street, and wuddya know, its sounds Exactly the same LOL.

onto rotors next.

Boost_Retard said:

my last diff lube change i had some silverish oil going on up front, it was magnetic but was so fine you could not actually feel it in your fingers, but the magnet showed it was there..i have always had a fine shine in the oil but this time it was pretty dark compared to my rear oil that was swapped at the same time and also runs a true trac

Click to expand...

Had a similar problem with my 2001 many years ago. Turned out to be a noisy pinion bearing. Just about drove me crazy trying to find it.
The metal on the magnet may be an indication of a bearing wearing out.'
With the shaft removed and wheels off the ground, turn the yoke by hand and see if it feels smooth.
You could put it on a lift or jack stands and run it with the wheels off the ground and see if the location of the noise can be isolated. Be careful trying this.

I did give the pinion yoke a spin last time I had it off the ground while swapping the drive shaft, felt good, BUT that metal is coming from some place. today I was spinning it but with drive shaft intact, no wiggle no movement what so ever..

just picked up a new 4 pack of 3 1/2 T jack stands, going to lift it up and get out the stethoscope.. cheap master install kits...cheap bearings