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Discussion Starter #1
My ’98 TJ (4.0L, 5-speed, Ford 8.8) has developed a high-pitched whine primarily on deceleration. I can occasionally hear it at a steady speed, but it is very faint. I cannot pin point where it is coming from even with the aid of 3 different people. KM2s don't don't help too much here. The pitch is very high (and pretty loud) but is right on the edge of hearing range so it is hard to identify. I’m pretty sure it is coming from the rear-end but haven’t ruled out the transfer case. Turning left or right has no impact. It does not do it when the Jeep drive-train is cold. After a short run down the interstate, it becomes present. It is mainly from 35mph down to 0mph just before you stop. When you apply the brakes as you are stopping, sometimes the noise will dissipate slightly – I’m thinking something is unloading.

What I’ve done (and has made no change):
1. Replaced my known worn (CY pin was galled) rear DS with an Adam’s.
2. Changed rear diff fluid (that still looked good and didn’t smell bad, extremely small amount of glitter present – I’d call it normal).
3. Change TC fluid (old fluid looked OK – still had some pink to it but dark).
4. Replaced a passenger rear brake caliper that was suspect as sticking (the dust seal was torn and loose).
5. Front and rear pads are both acceptable thickness (this is not seemingly a brake squeal).
6. Removed front drive shaft – the noise does not go away.
7. Removed rear drive shaft and the noise is less prone.

I’m thinking that acceleration pressure from driving is what makes the failing item develop heat and cause the noise. From the reading I’ve done online, it would imply the pinion bearing has lost its pre-load? This is probably starting to hurt the bearings, but i'm still just guessing. I have not put a socket to the nut, but I didn’t feel anything wrong when replacing the DS. I guess that’s my next check. Of all the axle bearings I’ve replaced, they have always growled, and you could make them come and go by turning left and right. I haven’t ruled out the bearings in the TC or SYE. I would assume they growl also.

Please help me out here as this sound and it's chase is making me crazy!
 

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Your Jeep is WHINING for you to remove that POS FORD 8.8 axle!!!:censored::):puke:
NOUN
the making of a long, high-pitched cry or sound.
 

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Discussion Starter #5
I used a temp gun on them when I got to work. It was making the sound. Both sides were about 95d. The center of the axle tubes were about 85d. The current air temp was 78d. The TC output was 125d and the pinion area on the diff was 120d.
 

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Discussion Starter #6
Figured it out. It wound up being the carrier race on the drivers side. I think it wasn't seated fully and caused it to get a funny wear pattern. It was also showing faint radial lines just like when you draw a cartoon of the suns rays.
 
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