Diff whine ... what does it sound like ?

[jeepinator]

After wheeling yesterday, and on my way home I heard two flutists playing in my Jeep ;)
I have not been able to track the sound down ... so I thought I would ask how others might describe diff whine ...

Does it sound like two flutes being played all crazy like ?
Does the whine change with speed ?

What else may be causing this sound ?

It really kinda sounds like wind noise, but it is more melodic and doesn't seem to change if I go faster or slower.

Oh boy, and it only has 3300 miles on :(

[TOOLman]

I have a little whining from the rear diff. It sounds like a steady sinus wave. The frequency increases with speed, of course. It's loudest somewhere between 55-70 mph.

Flutists, huh? Try switching your radio off maybe? J/K :)

HTH /Tommy

[justins311]

I have a little whining from the rear diff. It sounds like a steady sinus wave.

I have a sinus infection right now. When I breathe just right it sounds like I have 2 flutes playing beneath my nose! J/K

I have a bit of gear whine. It is not that high pitched though, more like a low droan. Hard to explain, but I definitely wouldn't call it a 'flute' pitch.

[Danno]

Mine has about 102,000 miles on it and since I installed the urethane bushings in the front I noticed a grinding type of noise that seems worse while accelerating but is present whenever the vehicle is moving. It is a very consistant and deep type of "groan...groan...groan." I don't know how else to describe it (other than like a sine wave).

I am debating if it is a pinion type noise or a wheel bearing noise. I have yet to diagnose for sure.

[TOOLman]

justins311 - I meant a sine wave of course. It's called 'sinus' in Swedish, and I just wasn't thinking.
Please bear with me, I'm a foreigner after all :)
Jeez, that was embarrassing!

[justins311]

No prob TOOLman! Just pokin' a little fun, I knew what you meant. It's actually a sinusoidal wave, so a 'sinus' wave is a more intuitive abbreviation. Us dumb americans shortened it to 'sine'. So what do you guys call 'cosh' and 'sinh' over there? Here they are pronounced like they read, which I always think sounds dumb.

[TOOLman]

As far as I can remember, I've only heard it spelled out, i.e. 'cosinus hyperbolicus'. Haven't really come across them a lot, though.

BTW, I can understand 'cosh', but how is 'sinh' read? :confused::D

[KevinF]

A diff whine usually is a lower pitch than what I would associate flutes with. Maybe more of an woodwind instrument? Possibly an Oboe? ;)

It does fluxuate, just like a sinus wave...er, I mean sine wave. It sounds similar to big mud tires with low air pressure on the highway at 60mph, if that helps, but with a sine sort of up-and-down noise, varying in pitch rapidly.

I don't know what your noise is, but it doesn't sound to me like a whine from the Ring and Pinion...maybe you crushed your exhaust pipe somewhere???

[KevinF]

Mine has about 102,000 miles on it and since I installed the urethane bushings in the front I noticed a grinding type of noise that seems worse while accelerating but is present whenever the vehicle is moving. It is a very consistant and deep type of "groan...groan...groan." I don't know how else to describe it (other than like a sine wave).

I am debating if it is a pinion type noise or a wheel bearing noise. I have yet to diagnose for sure.

Danno:
Your noise sounds like a pinion angularity problem to me. By installing your urethane bushings, you not only moved the axle slightlly (probably didn't get the caster precisely back where you found it), you also put in harder bushings that will transmit more noise/vibration to the frame under your feet.

IMHO, if it were a wheel bearing it would increase with speed, but not change pitch whether accelerating or decelerating. It appears that you have a classic case of too much pinion angle in the front. (the rear, BTW, is the opposite...noisy when decelerating, not accelerating)

[jeepinator]

Thanks for the help.
Oddly enough the noise has gone away !
Maybe the dang diffs were just really hot after wheeling all day, or maybe it was the mushrooms I ate ;) heh, just kidding.
I would sure like to know what it was ...

EDIT: DUH ! I figured it out. It was my CB antenna ...
Wow, I feel dumb. I have one of those tall wire ones. It is sitting on top with a magnet mount.
This was a cool thread anyway. I learned some stuff about sinuodal nodes ... er something.

[Danno]

Kevin,

That could very well be the case. However, the noise was there before the lift. It just was not annoying because I did not have the urethane. Interesting, when I installed urethane in my XJ a couple years ago, they did not do this. The original bushings were a little different too.

[sportking]

This message caught my eye, I have a noise that I have been unable to located as well. Too me it sounds like a dry bearing or brake pad rubbing (the noise does not change when the brakes are applied). The noise becomes loader with speed but is most noticable when you are slowing to a stop. I was planning to check diff lube and pull the wheels this weekend to do some exploring, if you have any expirience or suggestion the info would be welcome.

[jeepinator]

wowowow
I have not posted on here in like a year or something. I finally found the cause of the Star Trek sounding noise. Brace yourself... it was the CB antenna :)
I have one of the long whip type. It is mounted to my roof rack. When it is cold or wet (and especially when both) it sings to me. When I posted this question, the antenna was the last thing I thought it would be. Now I am used to it and trip out passengers with my sci fi sounding WJ.