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

Very likely.

Such a frustrating issue though.. I wish there was more consistency. I have a hard time believing that there would be such an enormous failure rate of differentials (~50%+ alone just based on the TW poll), across all production years for the 3rd gen Tacoma (including even some in the 2nd gen). Something like that would be extremely unlikely... especially if it was something as simple as impromper shimming, preload, etc, all of which could be corrected easily and at little to not cost. It would make zero sense for Toyota/HINO to drag the problem out over years.

 

So I reached out to someone at East Coast Gear Supply to ask about these differentials. I don't want to mention his name for privacy reasons, but this is what he came back with:

I thought it was very nice of him to go out of his way to write this. He did mention he might reply to this thread at some point and provide pictures of what he's talking about.

To any extent, it sounds as though there is nothing particularly wrong with the diff just that the gear design lends itself to being noisy. There's also a tech note on their webpage regarding the differential, saying that it's known to be noisy.

https://eastcoastgearsupply.com/i-23993416-8-75-tacoma-elocker-third.html

 

Wow man, this is top notch stuff. Good to know that he's of the opinion that these diffs are designed and built with longevity and robustness (its a word now) in mind.

 

Right on. Thanks for sharing.

 

Great detail! Would he happen to have any suggestions on toning the noise down? i.e., thicker or different oil, ect...

I said i would never lift another truck, but this noise is waring on my nerves. Aggressive tires and blocks seem to be the only thing killing it.

 

Blocks didn’t change mine. From what I’ve read, it’s leaf springs that do it. I’m still on stock tires

 

Thinking about trying this on the axle tubes (minus the pumpkin) and perhaps even on the leaf springs:

$22 Design Engineering 050220 Boom Mat Spray-on Sound Deadening to Reduce Unwanted Road Noise and Vibration

https://www.amazon.com/Design-Engineering-050220-Deadening-Vibration/dp/B001URKV0G

It's supposed to be made for automobile applications, and is black. My only concern would be preventing proper cooling of the differential and oil. I think the pumpkin needs to be kept bare metal to allow the oil to cool, so I wouldn't cover that.

I figure spraying the axle tubes would be reasonably safe, as well as the leaf springs.

The theory behind this idea is from a research paper on axle whine (https://journals.sagepub.com/doi/abs/10.1177/0954407011401302), as well as Toyotas TSB which implies that the noise is transmitted through the axle tubes through the leaf springs and frame, and into cab.

What do you guys think?

 

I cannot imagine this working
..b..but worth a shot just to prove me wrong. Do it.

 

It won't hold in enough heat to matter in the long run. I doubt it will work either, but it isn't going to hurt.

 

My other idea (I may try it first) is to get some weighted magnets off Amazon and place them in various areas on the axle, springs, and frame to see if the added mass changes anything.

Need to figure out if the bulk of the noise is radiated straight from the pumpkin, or if its amplified through the springs, frame, and body. That's the first step to finding a solution I think.

 

Aren’t these things the engineers would have (theoretically) tried before telling all of us it’s “normal”?

 

I did the following to attempt to reduce the rear end noise on a new ‘16 auto Sport 2WD during the first year of ownership and none of the actions remediated the problem.
- dealer replaced entire rear end assembly. Same noise problem after 100 miles
- dealer replaced driveshaft assembly, but no improvement
- lube replaced multiple times with different synthetic brands (Mobil1/Amsoil/Valvoline/Toyota/Pennzoil/BG additive), but the noise would return within 100 miles

Good news is that the ‘20 manual Pro and ‘20 auto Sport 2wd that I purchased have zero rear end noises after 4K miles of usage. Fingers crossed.

 

Man I swear, I'm convinced the engineering department ran out of budget half way through the NVH process for the 3G taco. IMO, the noise is so blatant and in your face that its like they didn't even try, hence why I think they just didn't get around to addressing it, and pushed the truck to market as-is.

Or they missed it during product testing, but I don't know how the hell you'd miss something like this.

 

Well clearly the noise isn’t there. That is why they didn’t miss it

 

I just spent 2000+ miles behind the wheel of a 2020 GMC Canyon diesel (I was transporting it for a friend before anyone gets crazy) and I will say I didn’t realize the noise that gets through the back of the cab on my Tacoma until spending a substantial amount of time behind the wheel of that truck. Thing was so quiet inside and now being back in my 2019 Tacoma Im amazed on the noise coming through the back of the cab. I don’t understand why, it’s not like I noticed thicker seats or more insulation back there.

I just stuffed some pipe insolation between a cab and bed to see if it dampens the noise at all. I imagine Toyota would have experimented with this already before issuing a much more expensive TSB to replace leaf springs, which did nothing on my 2017. Finger crossed, but almost certain it will change nothing.

 

I'm pretty satisfied with how quiet the cab is inside, except for the damn howl. It's like being stuck in a 1st world torture chamber at 55 mph.

Interesting idea with the pipe insulation though.

 

It is very quiet compared to the 2nd gens. The pipe insulation is something someone said worked pretty good a while back in this thread or another, I don’t remember, but its a cheap easy test. Sometimes Im exhausted from the issue but at the same time I cant believe Toyota would accept it, especially since the Tacoma legacy is built on quality and longevity. You would think after the first year they would have told Hino to redesign the DB22 differential or their going elsewhere.

 

If that pipe insulation idea works, that would be amazing. I'd be thrilled with even a 20% reduction... anything to take the edge off.

 

I'm so confused why you would buy TWO more new Tacomas after what sounds like a real headache, no pun intended (ok a little pun intended). Lol

Wish I was lucky enough to buy a '20 without the howling! Although, mine isn't that bad compared to what some have described.

 

Good question. Buyback done for the ‘16. I am a Toyota guy, so Last month I bought me a 2WD Sport, bought my daughter a Pro manual and got my wife a Land Cruiser Heritage. All good.