3rd Gen Poll: Rear End Noise howling when feathering throttle

Since I replaced my tires with 265/75r16s my howl now starts at ~50mph. Instead of at 55-60mph

Still there but not so bad this winter. We’ll see this summer.

I’m at about 36k miles and I’ve had it since ~1000 miles or so. On my second diff though which just made it worse.

 

To me, that would confirm the noise is isolated to the driveline (as opposed to transferred resonance).

 

Yes, the second one started after 1500 or so miles.

I’ll have to look back at the report. The tech said it was “a lot of metal” and “those gears were ground pretty good” but the report just said excessive shavings or something like that. Supposedly they replaced the diff but I’m not sure about the entire axle. The report was very toned down compared to what I was told but I can’t force them with what to write. The entire process was very controlled by corporate. Honestly, I’d just like for my truck to be somewhat normal. I searched for this one for over a year and this has been a bummer.

I would further note that my report said small amount of shavings but the dealer was shaking their head and saying they couldn’t say anything (after I was told what I was told of course). It wasn’t a big deal to me if it was a few or a million, I just wanted it fixed.

Part number, among others, was:
https://www.toyotapartsdeal.com/oem/toyota~carrier~assy~differ~41110-0k630.html

 

Not in may case. I would not call it just harmonics when I can maintain speed and every other variant the same and yet be able to actually make noise with feathering throttle.

 

It’s exactly that why I think it’s harmonics. An example would be this: I have a banjo hanging on the wall and only when you play specific notes on another instrument nearby will you hear the banjos strings ring to the vibrations in the air. I’m not here to say I’m right because I really don’t know. It just makes sense to me.

 

Ok lets go back to thread title. I don't say I'm right because I am not an expertise in mechanics. It's just my assumption based on similarity I see between my 2019 Tacoma howling noise and few cases of bad diff or tranny causing noises like this that I observed before.
I'm not familiar with music devices but as I understood, in your theory a source of energy makes sound then sound energy travels through air to a banjo where it is received by banjo and eventually causes string vibration. So you have 1. A source of energy 2. A media for sound wave to travel in this case "air" 3. Receiving component to make the noise
I am not quite sure how an energy source in drivetrain can travel to undercarriage and cause vibration based on your theory. It should be either a noise at first place or simply a vibration as a source of energy to travel to undercarriage. So why make it complicated. In both cases we have a drivetrain or diff issue at first place.
Now going back to thread title here "Rear end noise howling when feathering throttle".My theory is simpler; a flaw in some diffs or somewhere in drivetrain design which causes premature wear in diff making howling noise at a specific speed. I say it after reading Moondog repair history and replacing his diff with a new one. He had been fine for few hundred miles and then the noise comes back again after few hundred miles. Reading other people comments regarding TSB, the ones that got that TSB done are not 100% happy. It tells me that leaf spring mods and other stuff done in that TSB are not addressing the main issue.

 

Hi all,

New to the site and, consequently, the thread.

I have a 2018 DCSB Off Road trim. I get a whining sound above 25mph and a howling at EXACTLY 58mph. I can really only hear either noise with the rear slider window open and vents, radio off. The whining does sound like reverberations through the chassis. The howling has me concerned but is literally only at 58mph and doesn't seem to change much with throttle. Can anyone confirm (or reinforce) the idea that this is a sound/resonant frequency issue and not a mechanical one? It seems like some posters on here have bad diffs but some seem to think this is annoying, but normal.

 

What he's describing is resonant frequency and it does make sense that a normally operating mechanical component (diff, drivetrain, transmission, whatever) could hit that frequency under specific circumstances. For example, my voice seems to be the resonant frequency of a lot of aluminum tubing used in park benches. Consequently, it's uncomfortable to sit on those benches and speak in my normal voice. But if I go up or down an octave or even a note or two, no vibrations. That's why I wonder if the normal movement of pawls interlocking in the diff at 58mph (which a lot seem to cite as the 'sweet point') causes that resonance without anything being wrong. If, however, that drone happens under a variety of circumstances, there is something mechanically wrong. I am just trying to figure if, in my case, the diff is functioning normally with a resonance quirk, or if it's defective.

 

FWIW, mine was found by a corporate engineer to be defective. My rear differential was replaced with one that was church pew quiet. Then, about 2K miles later it started making the same noise and now makes them at different speeds. I guess what I’m struggling with is how the diff could be completely silent for a varying degree of miles from one to the next and then start the noise again. This is definitely an issue and one I’d love to see truly solved.

 

Gear patterns wear in causing different frequencies, thus changing the harmonic oscillation points. Possibly just a harmonic oscillation and never was or will be a problem with the diff.

 

I have had mine in the shop since last Thursday after and they have decided this noise is normal per Toyota. So normal in fact, that none of the trucks I test drove had this noise and none of the trucks on the lot have it either. I live in a hilly area with a 55mph speed limit so it is a constant aggravation.

If i heard heard this on the test drive it wouldn't have come home with me. I know this sounds like pissing and moaning, but my 62 F100's rear end is quieter and I expect better from a brand new truck.

 

Plenty of trucks I’ve driven don’t have a diff howl and are way smoother tranny’s. This was my first Toyota and I gave it a chance but that truck was constant stress for me. It’s not worth the stress. I got rid of mine.

 

What did you end up getting? I have no other vehicle I am remotely interested in at the moment. I have had a ton of Toyotas over the years and loved all of them. Heck, I would love this if it wasn't noisy.

I went a head and complained up to corporate, though I doubt it will go anywhere either. I can always drive my old Ford more, but it is a full on rattle trap! But then it has every right to be at this point.

 

I drove a Tj wrangler before the Tacoma and I ended up going with the new JL wrangler with a manual transmission. Really happy with it. Actually gets really good gas mileage too.

 

As others have stated I don’t think this is a problem other than a annoyance.
My Silverado did it for 250k miles, but that truck had more road noise in the cab than the third gen Taco. It wasn’t as noticeable.
Mine started doing the same at around 2000 miles. I’m not sure if some are louder than others. Changed the fluid in mine to Delco 75/90 synthetic and it is somewhat quieter. I’ve just learned to tune it out and turn up the radio.

 

Pissing and moaning with hundreds of other people (thousands?). I feel for ya. I do most of my driving at 60mph and that was right where the howl was the worst. I couldn't stand it. I traded my brand new 3rd gen after 2 months because the howl was so annoying. I wouldn't have bought it either if I knew the howl would start a month after i got it.

Dealer (and corporate) told me it was normal and there's nothing they could do. I felt like I got thousands of dollars stolen from me by Toyota. Obscene.

 

Anybody out there currently have the diff howl and want to do an experiment?

1) change oil and use Amsoil severe gear
2) change your breather valve to a filter (no check valve) I extended mine to behind the taillight

drive for a few miles and check back with me

My howl has been gone for 30k after doing these simple steps and I'm wondering if my results were a fluke

 

I did step one. I’ll try step two.

Howl for 31k so far

 

I've always thought that breather might be the cause

 

Did you have the tsb performed? Im terrified they might screw something else