Rear diff # 3. Howling

Wow. Not sure where to go with this. 21 TRD sport with the manual 6 speed. At about 8000 km the rear diff starts howling when feathering the gas at 90 km /hr. I’m at 44k and looking to call the dealer again for the 3rd diff change. I’m convinced it’s an issue with the 430 gears which the 6 speed comes with. I’m not sure the TRD off Road guys would hear it with the off road tires. At about 8000 km it starts to howl getting worse with time.I don’t abuse the truck. Never been off roading . Rarely pull a trailer. It gets loud enough the radio doesn’t drown it out. Love the manual but this issue is wearing on me. This should not be an issue with any 2021 vehicle let along a Toyota. Going to contact Toyota Canada to check on a resolution rather than just throwing parts and dealer money at the problem. I didn’t see any cures on the forum here. I suggested to the dealer to install redline synthetic diff oil. They assured me the Toyota spec oil is synthetic. Any accurate support on this topic appreciated!

 

Many possible solutions exist. Not all solutions work in all trucks. Start with the tsb and the cab dampers. Replacement gears are the least likely to work solution. Gear oil change basically does zilch. Good luck.

https://www.tacomaworld.com/threads...oise-howling-when-feathering-throttle.442341/

 

Not sure cab dampers are a fix as the howl goes away for 8000 km after a gear set change.

 

Harmonics. Resonance. These are the reasons. Can't live with it? Trade it. Sorry to be so blunt. My wife's vehicle makes no noise. Honda CRV. My truck makes all kinds of noise. I choose to live with it. It's actually comforting now.

 

The manual isn’t the problem, nor is the diff. The autos do the same shit on different gears with both axle sizes. Live with it, or sell the truck basically.

synthetic won’t make a difference, if anything g you want 85W-140 conventional, but way up in Canada that may not be ideal for winter.

 

Most do it, as mentioned, live w it or sell it off. It’s not going to fail, just a little noise if you can live w it.

 

I have the same issue with my 18 MT. Never had the diff changed but I had the revised cab dampers installed. It lessened the noise, but it is still there. Whatever...I still love the truck. I don't see them fixing it to your satisfaction. Just sell it.

 

Try a thick dino fluid in the rear Lucas 85/140. If the noise goes awayand since winter is approaching you can mix it down a little thinner. The thicker oils stick better. Quieted mine down for the last 8 months.

 

I have the same truck and with the same issue, the first dealer I went to threw a diff at it for a brief period of quiet. I tried changing oils, no difference. Threw rangs between the leafs because you could see them and feel them rumble with the noise like a tuning fork it was quiet, however thats obviously not a fix just a diag tool. Tried another dealer that applied a bulletin for 2018's of changing the leaves and installing those cab dampers. Honestly it was a little quieter but still there. At this point i'm over 153'000kms and I don't even notice it anymore. I know we're all making it sound hopeless...atleast Thanksgiving is on Monday.

 

Rotate the wheels front to rear, and see if the noise changes.

 

My brand new 23 does it, but only at a very specific speed, load and throttle position/coasting. It's not horribly loud, but it's there, if it gets louder I'll sell the truck and be done with Toyota for good.

Other than that the truck is growing on me. However I'm the type of person that won't put up with an issue like that, it's pretty absurd of Toyota to have not rectified the problem once and for all.

I plan on changing the diff oil at 500 miles as some suggest, I can't see it hurting. I ordered some Amsoil-75w 90 just because, but any decent lube will work.

 

Go ahead and change it, but diff oil changes have no effect on diff whine. I have Amsoil SG 75/90 in mine as well. You would be better off putting in a complaint with your local dealer and seeing if they have a TSB for it, etc.

 

Come to think of it...since i put on a tonneau cover i dont "hear" the rear end as much.
My thinking is the carrier bearing transmits sound through the composite bed easier than say a metal bed.

 

it is hard to believe that what you are hearing and experiencing is the diff. i am really surprised the dealer did or will (?) change the diff a second time. i do not know what your noise or issue is but the failure rate of diffs is not so high that you received 2 bad ones. the chances of that are statistically zero.

mine has the noise that you and many others post about. it occurs at certain speeds mostly going downhill coasting. had i not read about it on TW it is likely i would not have noticed it or thought anything about it.

i have 26K miles on the truck and the noise has not changed or gotten worse. changing diff fluid to amsoil had no effect whatsoever. when i changed the fluid there were no unusual metal flakes or darkening of the fluid. everything appears and drives normal as far as i can tell.

my $.02

 

Big box of Dynamat. Pull the rear seats, all of the carpet and door panels. Then cover everything you see but the wires and clip/bolt holes. Makes a serious difference! Way cheaper than new rear end parts.

 

What you are hearing is the sound that these diffs make. There’s a very good chance that there is nothing wrong with your truck mechanically. If your diff hasn’t grenaded yet, it’s unlikely that it ever will. It’s just annoying. As others have pointed out, the sound is amplified by the various harmonic relationships between the parts of your truck. My truck did it from day one. The sound went away when I swapped my wheels and tires. A different offset than stock, combined with AT tires pretty much eliminated the howl. I’d try new tires and wheels before doing anything else.

 

I hear some noise transmitted through my aftermarket shifter. I can affect the sound by lightly pushing different directions on the shift knob. It’s not bad but it is there.

Do you know if the pattern and backlash look good? If those are good, there’s not much you can realistically do other than try the sound deadening ideas.

 

57 MPH with light throttle. As predictable as the rising and setting of the sun.

Not worried about it.

 

My 2020 sr5 doesn't howl...never did.

 

I think you’re in the minority lol. My new 2023 sr5 with 150 miles doesn’t howl yet I’m hoping it never will. My last truck howled right from the start