Metallic whirring sound — parking brake cable

[bd100]

It took a while to track this down, but it may help someone some day.

Was hearing a quiet metallic whirring or hissing sound, related to road speed not engine speed. Noticable around 35mph and up. Sort of like a differential whine, and the fluid was in fact a bit low, especially in back, but these diffs have 13K miles on them and you'd think a fluid problem would have showed up earlier, and no change if accelerating or coasting, and no change after topping off the diff fluids with the official Mopar stuff. Not really swishing like a wheel bearing, and no change in sound during a turn. No change if in or out of gear or engine at idle or revved. No stones found in the brake rotors/shields. Nothing touching the drive shafts.

But the parking brake handle has had some slack lately. I was eventually going to go in and tighten the nut under the center console. But tonight I was out on a drive and pulled up the parking brake handle just slightly and bingo, the sound went away. Lowered the handle and it came back again. So somehow the slack cable is causing or picking up some noise. Definitely time to go in and tighten it.

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[jac04]

So somehow the slack cable is causing or picking up some noise. Definitely time to go in and tighten it.

I tracked down a very annoying whirring/whining noise to the e-brake cables as well. I ended up removing the cable bracket from the top of the rear differential housing and isolating the cables. It must be that the e-brake cables are transmitting & amplifying noise/vibration from the rear end.

If you are interested, here is everything that I went through. Post #39 is the resolution.
https://www.jeepgladiatorforum.com/forum/threads/unusual-noise-at-40-50-mph.46206/

 

[bd100]

Update: For my vehicle, the sound turned out to be a slowly failing differential. The first symptom was the hissing from the parking brake, which interestingly enough was carried from the differential to the cabin along the parking brake cable, but did not seem to depend on road speed, accel, or decel. Later came scraping and whining from the back, which eventually did depend on accel/decel.

Got a new axle under warranty.

So if hissing at the parking brake shows up, check out the back differential.

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