Rear diff # 3. Howling

-THIS- EXACTLY.

 

I’ve noticed that of lately, the noise is becoming less and less. I could hardly hear it this morning. May be because the weather is getting cooler. IDK.

 

Interesting the dealer just installed the 3rd replacement rear diff in an attempt to eliminate the whine at 60 mph. After replacement it is silent for 8000 km at least on the 3 previous rear diff carriers. After checking for leaks when I got home with it. I noticed a HINO tag and part number. Possibly Toyota is making a change in manufactures ? I’m not sure. They did install the bulletin a few months back with foam in the cab and new damping cab mounts.it did reduce the noise a bit but didn’t address the root cause of my issue. Whine while feathering the gas at 60 mph. Tried to get in the shop to have a look at the removed unit but the service guys are on flat rate and disassembling the old unit cuts into their pay cheque. 48000 km. Love the truck and I’m hopeful the hino rear carrier is a fix. Time and 8000 km will tell. lol.

 

I saw early in this thread someone mentioned a tonneau cover lessened it. I wonder if the bed is just amplifying it like a huge megaphone and if so maybe a rubber bed mat and tonneau cover will quiet it down.

 

I haven't tried it yet, but I read on here a few times that a pool noodle stuffed between the cab and bed helps a lot too.

I have had a tonneau cover in the past, and a topper now. For me, those made almost zero difference. I plan on soundproofing the cab and doors in the fall to help with all around noise but if I can get rid of the howl in the cab that'll be a bonus too.

 

I'm pretty sure all of the 3rd gen rear diffs are made by Hino. My 2020OR is and definitely has a whine.

 

I have both and really can't tell the difference with/without. No change after a diff fluid drain/fill; fluid wasn't that bad after ~30k mi. I learned to both tune it out and not stay in the 55-59mph range for too long.

 

Those would be resonant frequencies and yes, quite possible.

 

I’ll chime in on this as I’ve had 4 3rd gen’s, they all have had the rear diff howl, whine whatever you want to call it. Bought a 21 SR 4 Dr 4x4 with 29,000 miles in March. It had the factory steel wheels and was quite with no whine what so ever, was actually surprised. Found a set of factory set of SR5 wheel and tire package to spurce it up a little, as soon as I installed them the whine started. Just like all the rest. So what’s y’all’s take on this ?

 

Just had the tsb done on my 23. It’s better, not gone. It also changed the sound from 55 to 58mph and about half as loud. Diff plug was clean just a little fine particles.

I spoke to the master tech and he’s done several diffs. He’s found the truck assembly is more likely to make the tuning fork effect louder. In more then half of them the new diff can be louder. My heavier winter tires and wheels also reduce the noise, so I’m thinking 1/2 OEM block might change it up more. It’s cheap and easy to remove if it gets worse.

 

As I’m reading this , I don’t even know if mine makes the same noise . I don’t even pay attention honestly. Almost every truck I’ve owned made some kind of rolling noise.To me I could care less as long as it don’t break down I’m good . I look at my truck as a truck …. Trucks are noisy .

 

My shit is squeakin' and creakin' and howling along, but always starts up and hasn't given me any trouble so far. I'll take it

 

My 23 OR just hit 20k kms and has started doing this. It’s more like a humming/buzzing but the symptoms sound very similar. I see a number of comments saying this is normal but over the last year and a half since new it’s been fine. Only recently since it snowed I’ve switched back and forth to 4x4 a bunch and wonder if something got messed up there. I’ve booked an appt with the dealer but that’s like a month out and this is going to bug the shit out of me till then.

 

I’ve installed my winter wheels that are on steelies with larger and heavier tires. The sound is completely gone with the TSB now. I’ve also added RAS and 6112/5100 set at 1 inch in front. I would be curious if adding stiffer springs/AAL alone would help.

 

Like most Tacoma complaints the solution is to put the pedal down towards the floor more.

 

My rear end whines on cold mornings as well.

 

My rear end whines when i eat too much chili

 

My suggested solution is to spend more time at the gun range and/or rock concerts.

 

Unfortunately my tinnitus and diff howl are on different frequencies. No joy.