It just hit me with the thought if you has the cars standard rear end rubber bushings or if they are replaced to some race nylon/polyurethane bushings ?
Diff oil to quiet diff whining
- Thread starter alcyon
- Start date
I replaced it with a soft poly bushing. It is the softest I could get. It is somewhat compressible by hand.
Update. The last fill I mixed 67% Lucas 85W140 + 23% Lucas 80W90 and 10% Motorcraft XL-3 friction modifier.
Glad to report there is a noticable improvement in the sound reduction. I would say there seems to be a 40% reduction in the noise, so I am just gonna stick with this for the coming year.
Glad to report there is a noticable improvement in the sound reduction. I would say there seems to be a 40% reduction in the noise, so I am just gonna stick with this for the coming year.
Don't expect long term success. No oil is going to compensate for worn or an improper setup of a gearset. 40 percent? I suspect a mind over matter situation here.
does the whining start immediately, or does it get worse/better after a longer and faster drive?
The noise only happens between 60 to 70kmh on light acceleration or steady state cruising throttle. Nothing off power. If I lean into the gas at this speed range no noise at all.
but hot diff or cold diff it stays the same?
The colder the diff, the less the sound, however the thick oil really helps when the diff gets to operating temps.
Do you realize that really thick gear oil is going to make everything run hotter in use, which will be harder on the parts and cause the gear oil to oxidize much more quickly?
dnewton3
Staff member
4WD
$50 site donor 2025
Several name brands produce 85W140 in an actual formulation
100+0=100
100+0=100
Yes sir I do, but considering the ultra hot ambient temps plus I am mixing the oil so that it is not so thick like regular 100% 85W-140. Also keep in mind this is a high ratio diff of 4.556, not the usual 3.7 or lower.
Just keep an eye on oxidation as this will cause the gear oil to thicken rapidly and run even hotter. It’s a runaway condition after a certain point.
- Joined
- Jun 10, 2024
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I use Redline 75w140 in the duallies that work for a living and they don't whine about it. Lol I use 75w110 in the Tacoma with a historically noisy differential, radio off, absolutely no noise. I would try Redline 75w140 if you are worried about the oil getting beat up and oxidized.
With that said, both Dana 80 in the F350 and Dana M300 in the F450, with their extra capacity Mag-hytec covers run no hotter than 228*F. I have magnetic drain plugs and dipsticks in both, very very little black goop.
With that said, both Dana 80 in the F350 and Dana M300 in the F450, with their extra capacity Mag-hytec covers run no hotter than 228*F. I have magnetic drain plugs and dipsticks in both, very very little black goop.
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4WD
$50 site donor 2025
Extra capacity only slows the heat up to max …
The extra gear oil should help wrt oxidation …
Are these the flat back MT covers?
No, that is a process called "Micronite"
It is pretty well known that any gearset that starts with a 4 is likely to have a harmonic somewhere. Here, we normally have mud tires on vehicles with ratios like that, so the mud tires drown out the gear whine.
Seriously though, it is hot enough where you are that straight 85-140 will be fine...and that Lucas is a waste of money.
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- Jun 10, 2024
- Messages
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4wd, my unscientific inferred temp gun said 22* drop JUST with the covers over 300 miles at 38k Gross vehicle weight. I think your, I mean based on my data your info is not correct. If you are going to tell me that the "Flat back" covers are detrimental in some way because Banks the Salesman says they are, go ahead. I know different. While I know two guys that lost Dana 80s at 278k and 300k miles, I have run them over 400k without failure. They had the stock covers, I didn't, mine never failed and I'm usually about 5-7k heavier.
You bring up Banks, I'll bring up Project Farm...atleast he isn't trying to petal his average quality- at best products to you.
His exhaust have so much drone in the cab, in some rigs I wear ear plugs. His "safe" Scorcher power box took out a torque converter in a 68re with only 72k miles. He is a salesperson and nothing more.
You bring up Banks, I'll bring up Project Farm...atleast he isn't trying to petal his average quality- at best products to you.
His exhaust have so much drone in the cab, in some rigs I wear ear plugs. His "safe" Scorcher power box took out a torque converter in a 68re with only 72k miles. He is a salesperson and nothing more.
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4WD
$50 site donor 2025
It’s no different than putting a small amount of water in a large pot vs filling the pot … same source of heat … just takes more time to heat
