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

Maybe we are all confusing the rear diff noise for the “blowing into a glass bottle” whistle from the lower control arms. That’s a thing too.

Folks, enjoy your truck and save your worries for which mod to do next. If the diff fails, #warranty.

 

2 totally different sounds, plus they started plugging the lower a arms from the factory so its no longer an issue.

 

^
This is true.

 

We agree with you. No modern day vehicle should sound like this.

 

I somewhat get where you are coming from. However, from my experience of having been in a truck when a rear differential fails, the noise makes me more than a little nervous. Maybe that won’t happen for my sake and for Toyota’s.

 

Not possible to enjoy a vehicle that simulates tennitis.

 

Tacoma Drivers,

I've jumped into this thread several times looking and hoping to read the resolve. To date, it has not appeared. There are a few drivers who suggested they have approached rear diff experts and the expert conclusion was it's "probable" OK, it's just a Tacoma characteristic and the problem goes all the way back to 2002.
I must be one of the luckiest Tacoma owners ever, as I have owned more than a handful of Tacomas since 2002 and never had a a noisy rear differential and I am an off road guy.

I spent a day researching rear differentials on the net. Howling, if that is really what we have, is noted as a problem that needs correction. Some noted causes are miss alignment of the rear drive train, differential gears not meshing properly, and out of spec preload. My next step is to hit several of the top noted rear diff shops and document as many expert opinions that I can.

200 pages of read differential debate and not one "I took it to a top rated diff shop and here's the actual hands on, they took it apart report".

If I were stuck with my decision of owning a Tacoma with this problem, as some have commented they are, or feel that they are, I'd be at the best diff shop I could find to attempt to resolve the problem.

Why isn't that guy me? Cause I'm only on the list for a 2018 Pro and do not expect to see it till April, so I'm being as pro active as possible and doing my best to prevent a poor decision on my part in April. And, my 2011 DCSB TX Pro does not emit and rear diff noise of any sort.

Maybe the real best answer is the revert to 2019 and hope this year Toyota will correct the problem in stead of sticking there heads in the sand.


I would really like a new Tacoma, but I absolutely do not need a new Tacoma.

What ever info I get from the diff shops I visit I will share no matter what direction it goes.
Thanks

 

Yep. You were lucky.

 

My point is and has always been this...you should not have to take a brand new 30-45 thousand dollar vehicle to an independent shop to get a problem resolved that should not exist in the first place.

 

Did you miss post 3986 on page 200?

 

I think he referenced it.

I'm guessing without a report from the shop, photographic evidence and a signed affidavit it should be taken as anecdotal.

There's a huge gap between what is discussed here and what a shop will tell you. The conventional wisdom here is that the rear diff is going to fail, Toyota is a ruthless corporation who is pawning faulty trucks off on us, etc. etc. Some of that may end up being true, but what we have here is over 200 pages of general speculation.

When we went over my rear end after the swap, the tech and the manager walked me through where they would have seen wear. They went over possible reasons Toyota rear ends are historically a little whiney at certain speeds. Point is I didn't take notes and I made a promise to myself not to try to summarize their tech talk and possibly get it wrong. Shit, they even said they've done gear swaps on noisy second gens with high mileage and haven't seen anything other than normal wear and tear. When I explained to them that I had been told on TW that a noise was indicative of a problem, they chuckled. The tech said that all read ends make noise - they are mechanical assemblies that involve contact, friction, etc. etc and if they aren't making some sort of noise, they aren't working. He spends a good deal of his time listening for what is normal and what is not normal....and that what we hear or don't hear depends on the level of insulation, overall drivetrain noise, types of gears, type of driveshaft, how the crush sleeve is set up blah, blah, blah. He pointed out that my new gear set will have noise characteristics of it's own and outlined what is normal and what is not depending on the acuity of my hearing.

I had to strain to hear the noise when I had my original gear set. After I'd stop listening to it for awhile I'd have to re-train my ear in order to listen for it .

 

Seems unlikely that the air only flows past the control arms when I'm feathering the throttle.....

 

My howl seems to have gotten louder again after they rotated my tires.

At 10K I rotated my tires and the noise sounded muffled. Still loud but muffled.

Now at 17K and another tire rotation the noise is back to just being loud.

Not sure if there is a cause and affect here but its another thing to consider I guess.

I'm going to play with my tire pressure and see what that does. They're at 33psi now so I figure I'll go up to 36 or 38psi and see if that changes anything.

 

How many miles on the original gear set?

I wish my howl was hard to hear. I’ve had passengers in my truck who mid-conversation have stopped to point it out to me.

Gets kind of embarrassing.

I can’t even imagine trying to sell the truck now.

Anybody doing a test drive isn’t going to buy “Toyota told me it’s a characteristic of the double cab long bed, so your fine”.

“Next please!”

But Toyota keeps promising a TSB so my plan is to wait them out.

 

Depending on the HD radio song, I’m at volume 30-35 to drown the noise completely out. I think I have one of the loudest ones ha

Funny thing is it doesn’t sound that loud with the radio off. It seems like the frequency it’s at is just hard to cover up with any sound.

 

You and me both. Mine is that loud too.

Seems to have plateau'd though. I feel like it kept getting louder and louder until the current amount.

 

I've followed this thread for some time and being a Drivetrain (gearbox) Engineer for a wind turbine manufacturer i know a thing or two about gearing. Have personally written hundreds of failure reports and know all the tools and resources available to determine root causes.

Alot of the suggestions here for the root cause could be vetted and discounted in a matter of a few day from a disassembly inspection.

The first few occurrences were probably examined with with no abnormal wear found thus really no quick answers to the cause. Later issues were probably deemed as tolerance stack up issues (answer that makes sense but really means you don't know) and ignored because nothing abnormal was found at disassembly. Continued complaints warranted additional analysis.

I read somewhere the new 2016 rear ends were designed to be stronger, to me that meant higher pressure angles which means more noise. To me, I think it's likely a resonance issue. I'm hopeful to know that there is a TSB in work.

 

Very interesting inputs and conclusions, thank you.

This is a confusing subject to say the least. The 200 pages of information does not fully support the problem. Yet there are those returning New Tacomas to the dealership for refund the same or next day after purchase for the "noise". There are others with no "noise" being reported. Add to that it's reported here Toyota has changed out complete rear differential assys for some but not others with mixed results. Then there's the trend some subscribe to that the "sound", what every it is, a whine, a howl, or a resonance, emanating from the read differential is a normal Tacoma characteristic that stretches back to 2002. Yet there are 2016, 2017 and now 2018 Tacoma owners reporting no "noise at a variety of miles".

It would seem logical, if one agrees the rear differential "noise" is normal for Tacomas, then the opposite is also logical, those Tacomas with no rear differential noise are abnormal Tacomas.

I completely agree with "gears make noise" and fully expect some, but not enough to stop conversations while riding in a new Tacoma. If I have to strain to here it then I can live with it.

Visit to three of the top rated diff shops yielded an inconclusive results. All admit there there is something "different" with the Tacoma rear differentials with many request to regear. They all admitted the sound characteristics (whine and or howl and occurring at 50 to 60 mph and feathering throttle) would initially suggest possible bearings, alignment, gear mesh, or preload, but with out hands on it's only opinion. They also told me there would be nothing to gain by bringing a new truck in because all they could do is inspect it. They could not get OEM parts to attempt repair, especially for a 2018.

I guess I have to sit back and hope Toyota will provide some relief, be it more sound deadening materials or new mechanical parts, maybe 2019 really is the answer.
Again, thanks for you time, opinions, and suggestions.

 

There are a couple of things at work here.

First, some people have the noise - like I had - that you have to work to hear it. My co-worker has it and he's at 30K miles - he cannot hear it but I can.

Then you have some people who apparently have it worse.

I think everyone has the noise. I've pointed it out to people who have happily motored along without a second thought for thousands of miles. I've had to literally teach them to hear it.

 

Interesting. You're not the first person who's mentioned resonance..........