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

about 1200kms...700 miles

 

Yeah..on some vehicles the wind whistles at lower speeds across some holes that are in the lower control arms.The dealer diagnoses it by taping over the holes...if the tape cures it,they install body plugs.

 

Holes in lower control arms.... Really shouldn't affect sound in the cab, given that your lowers are way down by your front tires and shocks etc.

 

tsb 0053-16

 

"Normal Characteristic of the vehicle" canned response but its documented with the dealer. Time to turn the music up and deal with it

 

I think that's the best outcome actually.

I'd rather not have dealer techs messing around with my truck for days, driving it around, waiting for parts to come in, only to have the noise still be there or come back later.

I plan to voice my complaint to Toyota at my 5k, but unless they have an official fix by then, I'm not letting them replace anything.

 

I also think that's probably the best outcome haha. As long as you get it documented just enjoy the truck.

 

Little update since rear diff replacement on the 14th. All was good for 10 miles or so then whine showed it’s ugly face. Only difference is it went from 50-60mph to 55-60mph. Wasn’t really concerned before and and not really concerned now. It’s documented so if it gets worse I’ll cross that bridge then. This spring I might put some sound deadening material behind the rear seat and call it good

 

If you want to fix the noise just get some mud tires. . Had I had it to do over that is what I would have done - head on noise vs. noise. I have heard the sound deadening doesn’t work either. Best of luck.

 

Update: The new oil somewhat worked. I can only hear the noise between 45-55 mph on deceleration. Used to have the noise at higher speeds upon deceleration but not anymore.
Another strange observation. I took it for a 10 minute drive before changing the oil to so it would flow better. When I took the fill plug off, (about 10 minutes later) a bit of pressure escaped for about 3 seconds. This thing has a relief valve on it just like my 4Runner. I would have thought that the pressure would have released as there's nothing to the ball check valves. I didn't take it off and shake it but I will. Oh and don't use a 24mm 12 point socket on the plugs or be super careful if you do. I started to strip mine, I then used a 15/16 12 point which got it off.

 

Ditch the factory one way valve and put a two way breather in, tuck it up nice and high.

Won't help the whine, but it'll give you a functional diff breather so you're not sucking in water when going through crossings or backing the boat in etc

 

I think a mechanic's word or differential shop's opinion on this issue should be taken with a grain of salt considering the potential conflict of interest. If you look at all the literature out there on differential noise diagnosis, it basically says that *any* noise, no matter what, is not normal and needs to be addressed ASAP. The problem with this extreme, black and white line of thinking is that it completely ignores other sources or contributors to the noises, such as harmonics, amplification of small amounts of noise via springs, driveshaft and surrounding structure. Toyota has even official stated that this particular noise is caused by normal differential vibrations being transmitted and amplified via the springs, frame, and cab mounts. Their theory seems to make sense when you consider the sheer number of people who have received multiple replacement differentials and the noise always comes back.

There have been cases where these diffs have been taken apart and examined and no issues were found with gear meshing, pinion depth, or abnormal wear.

https://pdfs.semanticscholar.org/1404/a12c9dc2faa75c183d8a7be5f9f8e911110d.pdf

 

The vibrations/rumble strip feeling has actually gotten less noticeable with mileage for me. It was very noticeable the first 1000 or so miles, and now I can barely feel it. The howl on the other hand became an issue at or around the 600 mile mark, got progressively worse until about 1500 miles where it seems to have stabilized. So on my truck, the relationship between howl and vibration has been inversely proportional.

Let me ask you something, do you believe that *all* differentials, across the spectrum -- all makes and models of vehicles -- are silent? If the answer is no, then technically we are saying that the possibility is there for certain diffs, due to design, will make some noise regardless of how they are setup.

I believe that some gears simply make more noise than others due to the way they are designed... the way they are cut, the hardening, the way the axle housing is designed may amplify vibrations. Some diffs are just not designed well from an NVH perspective, but will last just as long, and perform just as well as any silent diff. I don't believe in the absolutist theory that all diffs, regardless of make and model, will be completely silent with proper setup. That's a theory that differential shops and specialists like because they need diffs to work on in order to survive!

 

I just noticed you have an SR, and I think those have different diffs. I agree it's a little weird that yours started at 8000 miles, but perhaps the diffs on some trucks wear-in differently than others.. most people I know who have the TRD OR with the BD22 diff seem to notice the howl anywhere from a few hundred to 1000 miles.

I wish you luck on yours though. If you ever manage to find a solution, please let us know!

 

About two weeks ago I opened up a case with Toyota about my 2020 off-road whining after the service manager at my local dealership wrote it off as typical Tacoma noise. I just finished up a like model ride along with the same service manager which was scheduled by my Toyota case manager.

They are ordering a new diff for my truck.

 

Good. The more diffs they're forced to replace, the more likely it is they'll actually fix the problem.

 

Keep in mind that the noise usually takes time/miles to set in, so new trucks on the lot likely won't have it yet. I guess in your case their not knowing that worked out well for you lol

 

Does anyone know if the Pros howl?

 

Yep! All the 2020s on the lot were brand new. It took about 2000 miles for mine to start whining.

My 2018 was silent for the 30k miles I had it. I only did this to add pressure to Toyota in finding a fix. Once they pull the 3rd member, they are going to allow me to examine, take pictures and compare it to the new unit prior to installation.

 

I’ve got a 2020 trd off road with under 200 miles that makes a slight howling noise going down the road. I will keep an ear on it and if things get worse I’ll take her in. Mine was manufactured in Mexico, not that it matters. Coming from an 18 Colorado z71 it’s light years better in every way!