Wank

First time user but have used/read this forum many times to help solve issues (VERY Helpful Site) and this issue really was not listed so I registered.

Here goes -

Marginal DIYer Mechanic
2000 Cherokee 150K miles
Moan/Groan that starts at 35ish mph and seems to have 1-2 harmonics up to 50 mph depending upon conditions
Definitely drive torque related - Always moans when powering, harmonics show up when powering up grades
Have been recently dumping upgrades/fixes into the vehicle
Increased tire size 245/70R16 (29.5" OD x 9.65")
Mild lift to accommodate tires, Only 1.5" - pucks up front / shackles in rear
New rear leaf springs
New front drive shaft
New front pinion seal
New muffler & hangers from convertor back
New rear brakes
New U-joints

Noise started when lift & tires went on
Got slightly worst with rear leafs went on
Got noticeably worst with muffler hangers (can be changed by removing)
No change with front drive shaft off or when new one went on
No change with new brakes
No change with new U-Joints
No change when smaller snow tires when back on
Rear diff sounds clean with hand rotations - Some torsional lash but nothing different
No lose heat or dust shields or anything real apparent to say ah ha

Thinking rear pinion angle - Did not measure but for a 1.5" lift really?
Hearing rear pinion bearing might be a possibility - No end play noticed but I'm grasping

Fearing Transfer Case or Rear Diff

BTW - The 3rd muffler hanger is on the T-case so I think that the noise relationship to the muffler is that the muffler has become a speaker for the drive line

Thoughts?

Wank

Sorry for this getting posted in the advance tech area - Obvious Newbie

dogger15

off topic but notice you in houghton, how long you been a yooper?

kurek9

check your echaust mounts i kept hearing a clunk under hard accelerating and i thought it was my driveline flapping. but it ended up being a broken exhaust mount and my pipe was hitting my trailer hitch and making the clunking sound.. i just used some tie wire and tied it up so it wouldnt move anymore

Wank

Went to tech in 79
Left in 85 came back in 93

You?

Wank

Good try

The exhaust mounts are brand new and and I tooked them off just to see if I could change the sound - Nothing Changed

Have a sneaking suspicion that it is temperature related

With winter coming on and temps dropping it doesn't seemed to be present for the first few miles

Thinking that fluids are thicker and that then leads me back to diff or T-Case

XJ D

It does sound like differential bearings are a possibility. Are you certain it is coming from the rear? on occasion. Sealed hub style front wheel bearings have fooled me on occasion.

Wank

Not sure of location

Wheel bearings were replaced about 10,000 miles ago but could be

How would that be related to powering (i.e. pressure on the gas pedal and going up grades)