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

I have a 2018 TRDOR I bough used in Nov of 2019, build date was 12/2017. So far I have now heard the howl from the rearend but I am curious as to what Toyota is saying this is. I have seen where some have had the rearend replaced and the howl is still there. My 2018 has 19,000+ miles, my '01 is still my daily driver back and forth to work, she has 341,000+ miles so no need to stop driver her now.

 

Toyota is officially saying that the noise has to do with how the ring and pinion are designed/created, and when these gears mesh at certain speeds it creates a harmonic condition that is transferred and amplified through the rear differential cover, axle tubes, springs, frame, and cab. They released a TSB (TSB-0013-18) that tries to lessen the noise by installing cab mount dampers, revised leaf springs, and adding some foam blocks in certain areas behind the rear seats.

Unfortunately, the TSB no longer applies to 2019s and 2020s as they have supposedly integrated the TSB fixes into the production line for these model years. Several people here with 2019s and 2020s, including myself have reported that they don't seem to have all of the TSB elements installed leading to more confusion as to what the hell is going on. And further confusing matters is that Toyota dealerships continue to be replacing differentials.

Now you are up to date

 

This is what I thought was gonna be done when I brought my 16 DCSB in for the rear noise but they ended up replacing the diff assembly. Odd how the howling started 2 days after a day of wheeling. Hoping it’s just the ring and pinion wore in and just needs the tsb your mentioning.

 

I doubt they would notice the diff breather mod, unless they're going to replace the diff.

 

Yeah, my opinion, based on the statistics of this issue, is that the harmonic condition occurs when the ring and pinion are broken in which would explain why everyone who has had their diff replaced so far, has noticed the noise returning within a few hundred or thousand miles. When the gears are new, they are tight, and tight gears affect the resonance characteristics.

FWIW, third party diff shops have disassembled and analysed these diffs and have concluded that there is nothing particularly wrong with them, only that they are built with strength in mind, and as such, are prone to making noise. I reached out to East Coast Gear Supply about a month ago and one of their techs sent me back an explanation of this. I posted it earlier upthread. They also posted a note on their website where they sell the OEM differential.

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

 

Years ago this was a problem as well. It was, the the time, attributed to Pinon/bearing preload which was done with shims. Many mechanics threw up their hands and said it cannot be fixed. A Few swore they could fix but it took trial and error on the shim thickness - you needed to pay them for the trial time - but said they would fix it 99 percent of the time and would not charge if they failed ... JMO

 

Yeah, a lot of owners think it's the setup. ECGS is a pretty reputable company when it comes to rear diffs. The message I received from the tech there implies that they have experimented with setup a number of times but were unable to get rid of the noise.

Their conclusion: Some diffs, like the 8.75 in Taco diff, are just prone to making more noise due to the type of gears used (tooth profile and metals used). They specifically said it wasn't a setup issue.

 

I think the name of the game now is seeing who can have the most success suppressing the noise. I’ll be trying some noico on the back cab wall. Im at peace with the whine, but if i can reduce it 25% to 75%, well thats a win to me. Just tell your self the whine means toughness! They maybe noise, but built for abuse.

Worse case, go the other way and add noise by a lift and MT tires.

 

I’m okay with the noise as long as I have peace of mind that’s it’s working properly. I bought it to go wheeling and be a functional semi daily driver.

If it’s working right I’m alright with the noise I just got a little freaked because the whining was louder than I remember at 55-60 but that could just be paranoia and the fact that it’s 36 hrs after a day of wheeling. I’ll find out Friday what the dealio is. Lift is next on the list of mods now that armor is pretty much done save for gas tank and diff.

 

Mine was just redone and quiet as a mouse now. Hope it stays that way.

 

High probability it will come back after the gears break in. Just be prepared!

 

Negative Nancy over here!






JK. I know we've seen that happen nearly every time so far I think. Here's to hoping.

 

He's right though, had 2 whole diffs replaced in my 16 and still came back a few thousand miles later.

 

Dealership wants 2 grand for the tsb, filed a case with Toyota but it is what it is. Geuss I’ll just have to ramp up the saving on the suspension fund.

 

I wonder if the axle tubes have been made thinner and are resonating gear noise? And even the pumpkin could have been made thinner than the older ones. Something in mfg is different than it was a few yrs back. Sure is a shame a new truck has this problem. Makes me hesitant to buy a 2020 right now.

 

Dealership tried to charge you for the TSB? What a bunch of crooks...

 

I’m just out of range of the 36,000 mile warranty and apparently it’s not covered under the platinum 120k warranty as it’s not a mechanical failure. I’ll wait and see what Toyota does, even if it doesn’t completely eliminate the noise I feel they should do the best they can lessen it. It’s something like 1500 for the new leaf springs and labor and 500 for the other new bushing things.

 

Boy howdy are they still being crooks.... Leafs and bushings are cheap, esp aftermarket.

Labor can be a pain, depends on how good your buddies are at slinging wrenches

 

Yeah the OEM ones are crazy overpriced

https://parts.toyota.com/p/Toyota_2...ht--Rear-Leaf-Spring/76185235/4821004701.html

 

Its honestly over blown like the transmission nonsense on here, I wouldn't hesitate. Its only noticable at certain speeds and the truck almost dead quiet, and not all trucks end up with it. I've had 6 turd gens various trims and configs, only had 2 of them with it.