UCA Noise

[Deleted User 61245811]

I heard a new noise a couple of days ago coming from the back of my Ranger. It only happened at extremely slow speed, like taking off from a dead stop and "accelerating" with no throttle, only idle speed. My first thought about the sound was the parking brake might be stuck slightly engaged. Kind of scraping with occasional light clunk sound. However, it probably wouldn't be accelerating without throttle if that were the case. Plus I pulled and released and reversed multiple times with no change. Tried to have the wife idle past me while I was outside to listen. Of course I couldn't hear anything. Sounds like its coming from the back of the truck when you are inside. Crawled under and found nothing suspicious outside of a small amount of oil stain around the rear diff fill plug (I just changed the fluid 3000 miles ago).

After more investigation, I discovered that the noise actually was happening with turning of the steering wheel. You could only hear it inside the cab and it sounded like it was coming from the back of the truck, not the front. A little research (much of it on this forum - thanks!) later, I decided the problem was probably the uni-balls on the new Grimm UCA's I installed less than 10k miles ago.

Because I'm camping, I didn't have much to work with, but I had some chain lube for our mountain bikes that is not supposed to attract dust. I cleaned the top of the uni-balls and hosed them down with chain lube. I let them soak in over night. Took it for a test spin this morning and no more noise. I guess it was the uni-balls, and I guess chain lube works on them.

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[Deleted User 61245811]

I'm curious if anyone has a theory why you could only hear it inside (and it sounded terrible) and why it sounded like it was coming from the rear of the truck and not the front.

 

[airline tech]

The sound was enhanced by traveling down the frame, you were inside the cab.
The acoustics of the enclosed cab enhanced the sound.

Sound can be tricky with how the ear locates direction, but time and distance of the sound travel - your ears perceived it as behind you (Traveled Past Your Ears) by the time your brain registers it was a noise (you were focused) on - the noise moved past your ears.

That is the way I understand (and the best way to explain) the brain vs ear and sound travel.

 

[Mighty Little Blue]

The sound was enhanced by traveling down the frame, you were inside the cab.
The acoustics of the enclosed cab enhanced the sound.

Sound can be tricky with how the ear locates direction, but time and distance of the sound travel - your ears perceived it as behind you (Traveled Past Your Ears) by the time your brain registers it was a noise (you were focused) on - the noise moved past your ears.

That is the way I understand (and the best way to explain) the brain vs ear and sound travel.

Agree completely with this, on my 2003 F-150 I had a noise II thought was rear shocks or loose bed bolts. After some diagnosing it turned out to be the bushings on the front sway bar. I was positive it was coming from the rear of the truck, but I could not find anything wrong so I started looking around and discovered the issue.

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