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

The last 3 Toyotas (different models) I have owned have had howling diffs. Our 2011 Highlander had the transmission replaced for the issue at 25K and it is back, to a lesser degree, at 100K+ miles. My 18 Taco has a rear whine in 3rd and 6th gears and I will have it looked at eventually. Previous experience has taught me to wait till near the end of the warranty period to get the most out of the 'fix'. What ever that might be.

 

Harmonic noise does not cause a problem ever. Think of a noise vibrating a glass. The glass makes a noise but unless it is the correct frequency and amplitude then the glass simply makes a noise with no damage forever.

 

Kazoo sound https://m.youtube.com/watch?v=ATWGa5JiNtQ
This is NOT the sound of the rear diff whine nor the harmonic noise.

The correct sound of you have the whine is this https://m.youtube.com/watch?v=thqB_OjQjb0 only much fainter and only when feathering the throttle at certain speeds. Again, mine is faint and only around 60 mph.

 

The noise is most likely in the drive train and like the master mechanic said on the test drive that something might be out of alignment or the clearance is not correct and over a long period of time, that could wear gears. It could be that Toyota Engineers may have their measurements off on something and it is causing the same noise on so many different model cars.

 

You have read the TSB right?

 

Yes I have, but I don't buy the resolution. I have reviewed several TSBs.

T-SB-0186-17: High Pitch Whine Noise from Manual Transmission

 

What is your resolution then?

 

All of this has been said before, but I'm now starting to realize no one really reads these threads.

I had the howl in my old 2017. I planned on doing a re-gear. Took it to the shop doing the re-gear (a shop that people come ship in cars from other states to do installs) and told them I'd like to pay extra for a tear down of the old diff when they were done.

Prior to that I had a lot of people with a lot of opinions and a lot of ASSumptions tell me the same things your master mechanic did - hell some them were also master mechanics. They had me seriously worried.

Typing in symptoms that your car makes is no different than typing in medical symptoms and reading webmd - everything on webmd leads to cancer, and if you google "rear diff howl" or "rear diff whine" you will be convinced the imminent implosion of your rear diff is nigh.

The diff shop, that does almost nothing but rear ends took a listen to the stock set up and said - and I quote "all Hino rear ends make this noise to one degree or another. They've been doing it for years. Nothing is wrong with it." Even went as far to tell me about the fact that the V8 T4s were famous for it as were the Lexus GX.

When I told them what other mechanics said, they shrugged and said this is what we do for a living, this is a HARMONIC noise, it can be annoying, but it's nothing to worry about. They took me for a ride in a Wrangler with a rear end that was improperly set up. The difference was immediately identifiable. This was October of 2017.

At the time, HiPSI and I swapped info over PM about the harmonic issue. He had heard the same thing.

Fast forward to the swap and the teardown. They laid my old set out on a canvas tarp and spent some time going through it with me. No damage, no improper set up. Nothing.

Six months later Toyota comes out with the TSB for harmonics.

You're going over old ground here and making assertions that were discussed over a year ago. This thread has laid out some solid info, it's also confused people and worried the shit out of others.

Here are the facts:

1. This issue has existed in the entirety of the run of the second gen. It prompted a TSB. My son's second gen has it as well.

2. It has also existed in the Lexus GX lineup and some of the T4 lineups at various times and had prompted TSBs....for harmonic dampening.

3. There is no epidemic of failing rear ends in any of these models. People can postulate the shit out of this, but this fact remains.

4. The issue has been identified as a harmonic drone - which is undoubtably annoying to some.

5. The TSB has resulted in a mixed bag of effectiveness. A mechanical engineer I work with who deals with dampening HVAC systems has explained to me why an effective fix for these type off issues is rarely achieved. This is due to other factors such as the length of the bed, the rpm of the engine, whether the AC compressor is on, the amount of dampening in the cab of the vehicle due to the presence of a rear seat, weight of passengers etc. He also said that over time the noise may come back as suspension components wear, lighter wheels/heavier wheels, bigger tires, smaller tires, blah blah blah, sliders, etc are installed. This is exactly what the rear end shop said as well when I took my new truck in for a re-gear.

6. I fully understand that this issue is annoying to people. If I wasn't fairly deaf from being an idiot and not wearing hearing protection in the field or while operating equipment it could possibly bother me. When I had the noise in my 2017 I would have to work to hear it, but soon learned it became compulsive and obsessive to identify it whenever I was in the truck. I rode in other third gens and had to point it out to the owners.

We can discuss this back and forth and my sympathy goes out to those who are affected to the degree that it interferes with their ownership experience. This is unacceptable and Toyota should do whatever they can to minimize or eliminate this noise. However, I look down my nose at people who come on here and try - without any evidence or expertise - to claim that this is not only a new issue, but one that will shorten the lifespan of the drivetrain. This issue has been around for a long time, across several models renown for their durability and serviceability. We can rail at how annoying it is, but I have a big problem with people trying to convince others that the problem is bigger than what it is (and yes, I was guilty of this as well). There is ample info in this thread where we don't need to go back two years and rehash the same shit again.

 

Great post man.

 

Mine sounded much more like your kazoo video than the video of the actual car. I don't mean this sarcastically. Just being honest. I must have had a bad case. There was no working to hear the sound. It was pretty much in your face.

 

I posted several months ago that the addition of a rear sway bar eliminated the howling on my Tacoma. I think the bar acts as a damper on the rear axle tubes, so less vibration is translated from the springs to the body. I haven’t noticed it since.
For those of you that don’t need full articulation of the rear suspension it’s a great option.
My truck spends most of its time on curvy roads or highway, so the rear sway bar has been an awesome upgrade. The handling improvement is night and day.
My off-roading is in flat sandy areas so the sway bar has no negatives for me.

I think the only bolt on option is the Hellwig bar. It requires drilling like 2 holes (seriously no big deal 5 seconds tops).

I used an X runner bar, but it was a nightmare to install.

 

Good to hear, thanks for the report.

 

I only had the TSB done not because i thought there was something mechanically wrong but to try and eliminate the howl. It only reduced it. Now i keep the radio a little louder to drown it out.

 

Care to elaborate?

 

I did somewhere previous in this thread. The X-runner bar is not designed for a 4 wheel drive pickup with a full size spare. The spring perches need to be filed down some, the exhaust needed to be slightly moved and the hangers filed down for clearance. It takes a very long time and lots of measuring to get a good 90° geometry while maintaining clearances and the spare tire.
The hellwig bar will bolt right on. Just get it. I only did xrunner because I plan on doing the x runner cross bracing and other handling stuff later. Also nobody had used that bar on a 3rd gen yet that I know of.

 

Thank you for the great write up and I appreciate you taking the time to write a through explanation. I can calm down now!!!

 

I addressed mine at the 10k service. It started around the 7k mark. My dealer "said" they had 4 techs look at the diff.
Toyota says its normal.....
I had a 2007 that did not howl.....
I did not purchase a 1950 log truck.

 

Updates!

The dealer performed TSB 0013-18-NOISY. (warranty charged $2134)

Basically they changed both R&R Leaf springs, installed PDS and Dynamic damper per TAS case.

The whining/howling noise has been reduced by 60-70% but not completely gone. I guess I just have to learn to live with it.

 

Sorry, man. That sucks. I was thinking about the used Tacoma market. It's just a crap shoot whether you get one that howls. I know that TW is a small sampling of owners, but it makes me wonder how many of the used low mileage trucks at the dealers were traded because of the howl.

Out of curiousity, I'd like to go drive all 8 used trucks at a local dealer and see how many howl. I know the one I traded is still sitting there after two months.

 

Anyone heard about this recent recall by Toyota?

https://carbuzz.com/news/toyota-issues-recall-for-some-trucks

https://gearjunkie.com/toyota-land-cruiser-tacoma-recall-2018