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

My truck used to do this. My brother thought my truck had a turbo. Lift and tires, no more sound. It’s a harmonic issue.

 

My 19 allegedly had the fix in at factory. Still noisy AF

 

They said it was on my truck from the factory. My 2018 is after the vin number range. However it sure doesn’t have the acoustic dampeners and it makes a ton of noise

 

These are the rear cab mounts on my '19. Are these the dynamic/acoustic ones?

 

It does sounds like it’s a harmonic issue in some cases. One way to check this might be to add some mass/weight to the diff housing to try to change the fundamental harmonic frequency of the entire assembly. Potentially it would shift the resonance to a different mode and you would hear it at a different point while driving.

Under ideal conditions, doing this would change the speed at which the sound became noticeable (IE - 48 mph instead of 63 mph). I think that’s why we’re seeing folks notice the sound going away when they add tires, armor, etc.

 

I was thinking about getting a couple of those big super strong magnets off Amazon to put on the diff and see if it makes a difference. But if it was that simple, I’d think Toyota would do something like that in the TSB, albeit a little more refined.

 

In case anyone is wondering, the 2020s have the rear diff whine too

 

this is what my 19 looks like, which allegedly had the fix but still makes tons of noise

 

huh, yours looks different for sure. That's strange. Did you take it in for the TSB?

 

Took it in multiple times, no one would touch it, ended up getting corporate involved, got an engineer to look at it, and was informed my (very loud) noise is normal - and that the TSB has been implemented at the factory line, mine was already done

 

Well wtf then Toyota. Why are our cab mounts different?

 

Could be yours was built before they implemented the fix

that or typical Toyota quality control

 

True. Yours look more similar to the dynamic dampers than mine.

https://parts.toyota.com/p/Toyota__Tacoma/DAMPER---FRAME-DYNAMIC/70025803/5122904010.html

 

My 19 has just started with the noise at 3300 miles. I get it right about 47-48mph. It's not real loud but for sure noticeable.

 

I noticed a howling noise around 70mph on my new 2020 with 400 miles. might have it checked out

 

70 would be an unusual speed for the howl. The normal rear diff/resonance howl is between 50 and 60 mph. I would advise waiting a bit before you decide to have it checked out, that way you can see how the howl evolves over time. It usually takes a few hundred to a few thousand miles for the diff to get broken in, and howl to fully develop. Even then, currently there is nothing the dealers will do to fix it. It's a normal characteristic of these trucks.

 

I feel like if something is normal it should be there from day one and not surprise you at 2k miles in.

 

Agreed 100%. Corporate engineers had no answer when I asked them why my second differential was quiet for 1500 miles. Then again they verified that my first one had gears ground and the pinion angle was off. I got a bit irritated with them and asked them what they planned to say when I deposed them. Crickets. I had too much going on at my real job so I decided to sell and move on. My last two Tacos gave me more problems than every other truck I’ve ever had combined. I love the look and capabilities of the truck and would love to see them get these issues resolved.

 

I’m having mine checked out on Friday for the same.

 

My 2019 had it from the first night i drove it home from the dealer. Truck had 4 miles on it when i test drove it. Didnt hear the howl until i got it up to highway speed on the way home. Hasnt gotten any worse currently at 13000 miles.