High pitch humming

[H3Wolf]

So when I'm driving, everything sounds normal, until I hit 40mph-50mph. That's when I get a high pitch whining or humming. This only happens when foot is on the pedal at any time until I let the pedal return and I'm just costing then I don't get any noise. Any ideas anyone? I'm posting a video, and it has me stepping on the gas during 40, and letting go.
https://youtu.be/EnqQVSRTy6E

 

[4speedfunk]

Front or rear? Sounds like a ring & pinion issue.

 

[H3Wolf]

Front

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[Happy Hummer]

Possibly tires, front hubs or axle?

Ive had my tires howl like that before. Also, the front unitized hub assembly.:no:

 

[H3Wolf]

I would agree, but wouldn't it be a constant state of noise?

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[H3Wolf]

Yea but the only time the nose happens is when coasting at 40, and then you slightly step on the gas pedal, then it's up and loud. If you listen close you can hear me playing with the pedal, and that is when you hear it start and stop

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[~MorninWood~]

I had that same issue. It was the pressed on bearing on the pinion and the race that it sits in on the front differential.


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[4speedfunk]

Yup. The pitch change when you transition to/from coast is a typical symptom of a bad pinion bearing. This is a common problem with the AAM-7.6. If left unaddressed it will eventually develop into a rattle, which will cause extreme wear on the teeth and usually a leak from the pinion seal.
Repair is not too tough but, does require some special tools. Another option is to find a good used front carrier to swap in its place. Many of us that off-road our H3's keep a spare front diff on the shelf. This way you always have a good one standing by.


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[mjferencak]

Sounds like our M1165s going down the road.

 

[Happy Hummer]

And this is why this site is indespensible​.

 

[H3Wolf]

How hard is it to replace the pinion bearing myself, used to work in a shop, but never on one of these.

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[H3Wolf]

Really sucks cause I have less then a 100thousand mile

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[4speedfunk]

It's much easier if you pull the entire axle out., and get it up on a workbench. Pull the diff & ring gear out of the case, then you can get a good look at the pinion and assess the problem. Most likely you'll need new bearings & races, a crush sleeve, and a pinion seal. Possibly a new ring & pinion if the teeth are worn.

Tools?...
Calipers
Bearing plate
Shop press
Torque wrench
Inch pound gauge
Dial indicator with a mag base
Brass hammer
Misc. hand tools

Frankly at 100k, you should just go for a complete rebuild. Master install kit.


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[4speedfunk]

If you don't have the tools & experience to do it...pull it out, un-bolt the drivers-side tube, and send me the pumpkin. Very small & cheap to send. I'll go thru the whole thing and send it back to you for $250 plus parts.

 

[alrock]

High pitch humming? Just learn the words to the song and sing it out. (Sorry, I had to do it.)

 

[H3Wolf]

LOL. Yeah that's fine. I would love to send off my differential. But it's getting sent to Hawaii on the 10th the July

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