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

What is the TSB?

 

Forget it. I looked it up. I will mention this to Toyota when I go. Thanks.

 

It was for the first few years of the 3rd gen. I figure they just included it with the later years.

 

My 2021 has done in since about 7,000 miles or at least that's when I noticed it. New fluid seems to work for a week or so before it comes back. I bought the harmonic dampeners and put them on, those completely stopped it for for about 2 weeks before returning. I'm at about 35,000 miles, if this is a problem is it covered under the 60k powertrain?

 

Yea. Was shocked to see all these posts from over the years and shocked Toyota never took care of it. Like a dope I sold my 20 trd off road and bought this 21 sr5 cause they were paying so much for used cars during Covid and it came back to get me. Truck seems to run fine just drives me nuts. Hoping this service fixes the problem but no confident it will after all I read. Had an 87 Toyota pick up. 2001 S runner. 2004 Tacoma , 20 trd off road. And now this 21 SR5. This is the first truck I ever had an issue with.

 

No howling yet in my 2020 sr5.

 

Wow! How have I not found this thread yet! I kept searching for whine or whirr but not not howl.
Checked out some youtube videos and could hear similar sounds. Is it a whirring sound for others?
I have about 19k on my truck and noticed it early on but seems to be getting worse, almost unbearable as it's all I can hear!
Glad to know it's not just me but super frustrating for a new truck this late in production...

 

after talking to a person from toyota,, the manufacturer that builds/assembles the rear differentials are not always setting the pinion depth correctly.. it is suggested that the gear pattern be check before install into rear axle housing !!

 

I'm at I'm 180k + miles still whines and I'm still fine . Just change fluids every 30k miles

 

Known to be false.

 

Known? I mean I don’t believe they don’t check it but I don’t absolutely “know” they don’t check it.

I’ve also set up my fair share of third members to know there’s plenty tolerance either way.

 

Given the number that whine and never blow up points to not a setup issue. Given that perfect setups of new/used, oem/aftermarket gears have been performed countless times by the most respected gear shops and still will whine points to not a setup issue. Given that these top gear shops that have the most experience with these gear sets include a disclaimer that they won't chase "gear whine" points to not a setup issue. Given the total number in use that are not failing or blowing up period points to not a setup issue.

I've said it before, gears make noise and have inherent vibrations. In the wrong system there can be resonance and harmonics that are audible and annoying to humans. It's not a gear issue, it's a system level NVH issue and that is why it's not gears that are a solution to this problem. You have to change the characteristics of the system being excited with something like different tires, leaf springs, cab mounts, topper, etc.

 

That’s an interesting statement and I never thought about it. Yes, I understood it was harmonics. I had a high howl only when soft petaling/deceleration about 50-70. Just ignored it as part of the truck. Your mention reminded me, It’s gone. Haven’t heard it in quite a while. I did add a leaf to the pack and relube the friction points. Never questioned the gears based on past comments and clean drains and chip magnet drain plug.

 

I dunno, Toyota told me it was my rear diff. Replaced it even.

Then changed my cab mount, leaf springs. I put a topper on my truck and different sized tire etc. Still have the noise. And for the record it’s not “gear whine” like a poorly set up gear set. It’s more of a resonance like a tuning fork. I also hear it in other cars now. I’m finely tuned into it.

My opinion is whoever is making these third members is using poor metal quality (probably too hard).
All that said I have 85k miles on my current diff and I don’t think it’ll fail on me. It’s just annoying and if I ever try and sell it it’ll be an uphill battle to convince anyone that it’s normal.

 

The noise reminds me of a school bus as a kid. I hardly notice it in mine - its faint, decel with narrow mph window, downhill. I have 4.88's built by ECGS and the truck did it before even worse with the stock diff. Also have a hellwig rear sway bar. Break-in and fluid change def quieted it down. Ordered the dampers as my 2021 didn't come with them - interested to see if they help. Plan on removing the interior during the summer to sound deaden it anyhow.

 

Got my rear differential replaced yesterday on 21 sr5 with 5,000 miles. As soon as I drove off the lot the howl was still there on deceleration. Went right back in to dealership. They made a case with Tacoma. got a call tonight that said Toyota will not be repairing any more on your truck. That the howl is normal. I said it's not. I had a 19 and a 20. None made noise. They said I'm sorry. Nothing further we can do at this point. I said so it will just howl. They said it's normal. I said it wasn't normal when you said I needed a new rear differential?! They said I'm sorry. Nothing more we can do. It's normal.

 

fwiw, i put in amsoil severe gear (

$30 75w-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75w-90) in at 500 miles and i haven't heard any howling/whining yet at 17,000 miles. the break-in process is extremely important with rear differentials. this may explain why some new units will make noise.

 

Had several Tacomas over the years. This is a weird problem that I think only happens to a few.

 

Interesting!

While my rear end is not the quietest it sure never howls. When I regeared to 4.88 I dumped the break-in fluid after 500 and went 75W-110 Severe Gear.

 

yes - noise is much less with

$30 75w-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75w-90 (I used Castrol synth) vs 70w-140 or higher viscosity in my experience