Mystery noise help

[CaliSteve]

Hi All,
I have a very high frequency noise coming from the back of the jeep. I don't hear real high frequency noises but the wife has excellent hearing and it drives her nuts. Others have heard it also, I can drive the jeep around all day on short trips and no issue, once I put some continuous miles and constant driving it appears. It only makes noise when I am moving, starts at about 5 mph the more speed the louder it gets. I was thinking perhaps a brake issue, still happens while dragging the brakes. New rotors and pads a year ago, by the dealer I purchased the jeep from. The jeep has been re-geared, new axles installed so the running gear is all new, including SYE and drive shaft. Had the noise before the work was done. The wife describes the sound as the squeal you make deflating a balloon when pinching the opening as the air comes out. I don't want to just start replacing parts but have been chasing this for quite some time. Have taken the front drive shaft out and no help, have not driven it with the rear shaft removed.
Any input would be helpful

 

[GabeSpeakeasy]

Rear u-joints most likely

 

[CaliSteve]

Rear u-joints most likely

Thanks for the response, new U joints went in about 800 miles ago when I had it re-geared and new axles installed.

 

[GabeSpeakeasy]

Thanks for the response, new U joints went in about 800 miles ago when I had it re-geared and new axles installed.

Did you drain the gear oil after breaking in the new gears?

 

[CaliSteve]

Did you drain the gear oil after breaking in the new gears?

Yes I did

 

[Quigley]

Have you jacked up the rear end and spun the tires to listen for the noise at each wheel?

 

[CaliSteve]

Have you jacked up the rear end and spun the tires to listen for the noise at each wheel?

Yes we have, had it in gear running with tires on and tires off, if it sets for a few minutes the noise won't appear until you drive it a few miles

 

[Quigley]

I had axles installed when my locker was and they had to be cut down. I didn't notice until a year later when I went to do brakes that something was off and they had to be cut a bit more. since they were a little long it took out the bearing as well. This might be an option, but I would try driving it without the rear driveshaft first and check the diff fluid to make sure it is correct. You never know what a shop might accidentally overlook. I left a tire shop once and they forgot to tighten all the lugs nuts!! wheels almost fell off driving down the road

 

[CaliSteve]

I had axles installed when my locker was and they had to be cut down. I didn't notice until a year later when I went to do brakes that something was off and they had to be cut a bit more. since they were a little long it took out the bearing as well. This might be an option, but I would try driving it without the rear driveshaft first and check the diff fluid to make sure it is correct. You never know what a shop might accidentally overlook. I left a tire shop once and they forgot to tighten all the lugs nuts!! wheels almost fell off driving down the road

Have driven it with each drive shaft removed and still no luck, the diff fluid is at the proper level.

 

[Quigley]

Damn... does the noise get louder or faster with speed?

So far you’ve checked brakes, diff fluid level, driveshafts, had new axles installed but sound was there prior to that as well.

Worn bushings in the control arms or track bar? Rubbing exhaust on shock or coil?

 

[Dan Carey]

An exhaust leak can cause a high pitch squeal

 

[CaliSteve]

Damn... does the noise get louder or faster with speed?

So far you’ve checked brakes, diff fluid level, driveshafts, had new axles installed but sound was there prior to that as well.

Worn bushings in the control arms or track bar? Rubbing exhaust on shock or coil?

Control arms are 1 year old, put new Currie system on last April.

 

[CaliSteve]

An exhaust leak can cause a high pitch squeal

I hadn't given that any thought, I had a new Magnaflow muffler and tail pipe section installed a few months ago, I will give that a good look.

 

[Dan Carey]

If you have some help, have someone shoot some seafoam in the intake while you are looking at the exhaust system.

 

[AndyG]

Man don't rule out rear wheel bearings , and also don't neglect looking more forward , noise sources can be deceptive . An exhaust leak at the pre cats can make a racket .