Just another Differential harmony thread. Might as well move along.

So I've got the noise. Maybe I am sensitive to it because the plethora of threads about it but I've arrived.

Anyway it seems to me that the sound comes when feathering (different thread) the gas pedal. So that the truck is somewhere between a coast and drive or my guess between the teeth? Like that small area in the back lash where there is little to no pinion to ring gear push? It seems like if I'm on it and pushing forward no noise or if I'm using compression to slow, no noise.

If this was the case I should be able to replicate it all the time regardless of speed and I think I can between about 40 and 60 mph. Perhaps slower and the sound is minimal and any faster and my autotranny tries to shift which pushes the pinion gear.

I dunno. I've set up the diffs in my '85 a handful of times so I get the mechanics. And they don't howl or maybe they do and all the other drivetrain/tire/motor noise drowns it out.

Thoughts? Or point me to someone who has made the same conclusion and I'll commiserate.

 

I've got it. Faint whistle, right at 60, just at the very slightest push of the right foot. Funny but I can only hear it in the cab. I can't hear it rolling down the window.

I have a 65 Chevy that had a bad rear-end in it. I remember that thing squealed constantly, didn't matter if you were running 5 or 55. I'm not saying it should whistle, but there has to be something other than bad parts.

 

That's what I'm thinking. More of a byproduct of something else happening. I mean Toyota has been putting ring and pinions together for ever so what changed? I know they moved the locker actuator into the diff but that's not new. Also people without the locker are getting it.

 

Actually now that I'm thinking of it I only assume it's coming from the diff because it's a common theme on here.

I'm going to dig and figure out the method they used to narrow it down to the differential.

Maybe I should have done so before starting another diff howl thread...

 

Here's something else to consider... you're in an auto, mines a stick. Two different ratios. You would think one more than the other would be prone to do it!

 

I'm thinking it's more putting slack in the drivetrain regardless of diff gearing. *edit after rereading post.

Although it seems replacing the diff fixes the problem for awhile. That throws a wrench in my idea.

 

It's possible that a new manufacturer or facility is making the diffs?
Nobody is really sure that I'm aware of what the true issue is. All that's known is that Toyota is aware and replace diffs on some people's trucks and not others. Some diffs have failed and some people seem to have no problems that they are aware of. It's a very inconsistent problem and shrouded in mystery due to the fact that Toyota is not officially commenting on it yet.

 

On a side note I have ALOT of 75/90 gear oil from a VERY reputable manufacturer in sealed bottles that I'd be willing to give to anyone looking to try it out.
I read somewhere that this diff calls for 75/85 but I donno what it calls for truthfully. I'm not sure anyone would want to try this as it could potentially cause an issue if it's not the correct weight but the offer is out there

 

Also I've never owned a brand new car before. Usually when I notice something on one of my cars I google it and come to a forum (like this one) and they have an answer to what it is and how to fix it.

Not the case obviously for this issue but I'm all for figuring it out.

 

Do you think the howl and failures are related? I don't know.

 

Who knows honestly

 

I read where someone did change their fluid and added antisqueek from Lucas and it didn't help.

I'll look it up. Hold on.

 

https://www.tacomaworld.com/threads/hum-on-deceleration.475220/page-4#post-14581464

Page four

 

Ok so I reread it, page four on, and it did seam to help. He said it was still there but quieter.

So if there is a product that helps then this is not a novel problem and maybe I'll spend some time with google to find other cases of it.

 

Oh and I notice that your @TRDinOhio all over that thread I linked.

 

Purely speculation. Nobody really knows what the true issue is that I'm aware of

 

Are both rear-ends the same components? Is a ring and pinion for 3.73 gears physically bigger than for 4.30?

 

Changed the tread title

 

That is the first thing that came to mind for me, they probably switched to a different supplier.

 

Pinion gear would be right? Still both either 8" or 8.75" ring gear.