Open differential and transfer case - additive?

Messages
395
Location
VA, US
I have a 2011 Toyota RAV4 4WD with a small whine from the differential at about 30-40 mph. This was a well known (TSB) issue when cars were in warranty, but I bought mine used, so there is no warranty.
The car has one transfer case in front and one rear differential, electrically controlled.

I have drained and refilled the boxes - each takes about 0.5 Qt of fluid (80W90 GL5 is factory). Used 75W90 SynPower and then Redline 75W110. Still the same, a lot better with the Redline. But I can still hear it (maybe because I know it is there).
I want to make sure those gears will outlast the rest of the car, even if I pull a 3,500 lbs trailer, so I am now looking into one of those two additives:

- Revitalizant EX120 for manual gear box
EX120 can be universally applied to manual and robotized transmissions, sequential gear boxes, including Direct Shift type, transfer cases and differentials.
Revitalizant acts as a catalyst for rebuilding and repairing metal in areas of excessive thermal energy. It activates the absorption process of carbon through the surface layer which results in the formation of metal carbides. Revitalizant rebuilds metal at a molecular level, atom-by-atom. A new durable protective coating is formed with the help of carbides and metal particles. Because it has a self-regulating maximum thickness it does not cake. Diffusion of the protective layer into the metal results in an extra durable gradient coating with positive pressing stress forming along the entire treated surface in the final stage of Revitalization. The treated metal is now rebuilt and protected with diamond-like film of ceramic-metal, resulting in smoother operation and longer life.

- Liqui Moly 2019 MoS2 Anti-Friction Gear Lubricant
Stabilized solid lubricant concentrate suspended in mineral oil. Thanks to its high MoS2 content and special additives, it is suitable for all manual motor vehicle transmissions and differentials without limited slip function.

Anyone had experience with any of those?
Please don't post if your jerk-knee reaction is "use only what Toyota recommended". They were so great in building those transmissions and differentials that they replaced a bunch of them in warranty.
 
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Messages
2,393
Location
Paradise of Florida
I would use soundproofing. No additive will help. 4 or 6 cyl? You probably won't tow 3500lbs well with the 4cyl and the 2gr is definitely lively in the RAV4.

Pull the seats and carpet out, and add a sheet of soundproofing to the floor/firewall area, and keep driving. Visit a stereo shop!

On the Highlander, some of the similar transfer case noises/whines were addressed by sticking on wheel weights as the 'soundproofer'.
On the RAV4, I vaguely remember Toyota replacing with better isolating drivetrain mounts and stuff which didn't work.
Find the TSBs as the parts are a supposed upgrade.
Don't remember if the Sienna AWD had the issue.

They all suffered from the leaky seals so pay attention to ATF level, drips in the driveway, and transfer case fluid condition.... no ATF coloring... Change xcase fluid often like every year or 2 at most.

My transfer case runs 75w140.

The other option is to turn the volume up on the radio. And, if doesn't get loud enough, that stereo shop with the soundproofing can also address the music too.

Will assume that your driveshaft u-joints are good and that you haven't already trashed the x-case bearings from low level or neglect.
 

SoNic67

Thread starter
Messages
395
Location
VA, US
Will assume that your driveshaft u-joints are good and that you haven't already trashed the x-case bearings from low level or neglect.
Yeah, this is not my first 4WD/AWD vehicle, that's not an U-joint noise. It's a barely noticeable gear whine between 30-40 mph (with the radio off lol)
I don't want to mask the noise, I want it gone.
The T-SB-0130-12 first replaces the engine/transmission mounts. If that didn't help, then they replace the prop shaft. If that didn't fix it, they replaced transmission. They have another T-SB-0080-13 about rear diff front bearing.

I want to address any mechanical imperfections in the TC and Diff gearing. That's why I asked the question about those products.
 
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Messages
2,393
Location
Paradise of Florida
I don't see it as an imperfections. I see it as a harmonic. All mechanical equipment makes noise. Some of that noise can be tuned out. Toyota failed with the soundproofing. Where I come from, if a machine is quiet, its not running.

For a transfer case and transmission, polish it with a run of ws2 or ceramic/boron.

Don't expect a fix in the bottle. You can keep swapping parts until you change the harmonic where the whine is not noticeable.
There is no mechanical imperfection. Even if you don't hear it, its still there either at a lower volume or at a frequency above/below what you can hear.

The noisiest thing on your car is your brakes...just ask any dog. Shoes/pads are tuned to produced as much noise as possible outside your hearing range, but not Fido's. Toyota failed with the known transfer case and 5-speed automatic noises. Combined them both in the Sienna/Rav4/Highlander and a non-deaf person will go postal.


And, I doubt that any would perform any better than a diy dosage of the colloidal ingredient:

I would also change the ATF filter too. If your transmission calls for WS, use the Amsoil/Redline product. BTW, the 5-speed was built around the standard viscosity T-IV, hint hint. Might just change the harmonic.

My coins make no noise. They just sit there on the table silent. My door pockets, ashtray, center console make no noise. Put the coins in all three and suddenly I have noise coming from everywhere.

Get the soundproofing. Unless you swap out the drivetrain, multiple times to find a quiet combo, the noise will always be there.

10 year old car and now its a problem!

Gotta run. Neighbor has a noise problem with new tires in his Jeep. Every since he put on new Interco Boggers, it howls on the road at all speeds. Might have to convince him to offroad in some Serenity tires.
 

SoNic67

Thread starter
Messages
395
Location
VA, US
BTW, the 5-speed was built around the standard viscosity T-IV, hint hint. Might just change the harmonic.
That's a good point, thanks.
I drained out from transmission the black factory WS and put in AISIN WS, that's full synthetic. I might consider a fluid with a bit more viscosity (AMSOIL has also synthetic with normal viscosity) or to dump some of those new "nano" additives.

Unless you swap out the drivetrain, multiple times to find a quiet combo, the noise will always be there.
I drove a 2001 Ford Explorer AWD (V8), couple of Mercury Sable (1996, 2001), a Hyundai Sonata (2000), wife's Kia Soul (2011) and on none of them I heard any whine. It might have been, but it was in a band that I could not hear. And yes, I have pretty good hearing, I didn't shoot guns without ear protection like one my friends.
IMO, it's not normal for a properly honed transmission. If there are noises, something rubs too much and metal vibrates at medium-high frequency. It might affect gas mileage, temperature... So I am looking to quiet them down by reducing friction, not by sound proofing.

Tungsten Di-Sulfide (WS2) sounds intriguing. That link has 1lb bags, it's a bit too much.
The mix should be 1-15% by weight, my TC/diff take 0.5 Qt each. That's almost 0.5 lbs = 8oz. So the mix would require WS2 like 1-1.2 oz for each.
Microlubrol sells 2 oz bottles for $25. I think I'll try it.
 
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Messages
33
Location
TX
Pardon my limited knowledge about the Rav 4, but if the rear diff is electronically controlled, does that mean you can engage/disengage it at will? If so, does that have any effect on the whine?

Since you've tried several gear lubricants to no avail, I doubt an additive will cure your problem. Also, I wonder how many of the whine problems were actually cured by the Toyota "shotgun approach" TSB?

I'd suggest finding another diff at a junkyard, but given the longevity of Toyotas, that might be next to impossible to find. And even then it could be noisy, too.

In the hot rod world a whining noise from the differential can be the result of inexpensive ring & pinion gears that aren't honed to optimally mate with each other. The noise can also mean things were not set up properly, such as pinion depth or, more commonly, too much ring/pinion backlash. All the lubricants in the world won't fix those problems, but 75W140 might quiet down the backlash issue a little.

One last crazy thought: I once had a brand new 86 Mustang GT. After only a few thousand miles, I started hearing whining noises in the rear during moderate-to-heavy acceleration. I would have bet money that it was the diff, but it turned out to be the Goodyear Gatorback tires! I rotated the tires front-to-rear, and problem was solved, at least for a while.
 

SoNic67

Thread starter
Messages
395
Location
VA, US
does that mean you can engage/disengage it at will?
It's controlled by the 4WD ECU. Connects it at starting from stop and if it detects slippage.
RAV4 also has a button on dash that says "Lock 4WD", but that lock works only to about 20 mph, then disengages.
Most of those Cute-SUV's are like that, no real central differential on them. Exception is Subaru AWD, but then they have poor engines to "complement" it.
inexpensive ring & pinion gears that aren't honed to optimally mate with each other.
I understand that this was the case here too. Replacement parts were "special honed". It might not affect the life of the gears... I'm just a tinkering type.
 
Messages
33
Location
TX
Replacement parts were "special honed". It might not affect the life of the gears...
I think that's correct. It's just noise. I read this about Yukon Gear, a company that sells "premium" and "standard" R&P sets:
"If the contact portions of the ring and pinion don't meet tolerances for a quiet gear (too rough), then the gears are downgraded to "USA Standard" rather than tossing them in the trash. It's still a great gear set strength wise, but in some instances they can be noisy."

For those reasons, many off roaders and hotrodders, use the "standard" sets.
 
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Messages
5,006
Location
Southeast
Ive found that thicker fluids can drop the volume of gear whine some, but never quench it. I totally understand where youre coming from Sonic67, we’d expect our precision equipment to work without flaw. My 2018 f150 has developed 55mph gear whine, only noticed on quiet drives, radio off, hvac on low. It bugs me a little knowing its not right. Otoh, whining and growling diffs can oulast the car.... ive had 2.

if you wanna go for it, amsoil severe gear is IMO the go-to mama-jama for gear lube. They also have a 110 weight if you wanna go heavier without going 140. BUT.... question.... are we talking about the rear? The rear wouldnt be under load in most cases, but IME diffs which make noise, do so the most when they are under load. You‘re probably correct in your assessment, but just to eliminate outliers have you rotated the tires?

if you do tow, the amsoil svg is extra insurance, even if the rav doesnt need it.
 
Messages
178
Location
NV
My RAV4 transmission whines, I dont hear it from the rear diff.
I use Delvac 75W-90 in the rear diff and Transfer Case.
 
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