diff oil levle change ?

[jethro]

Tossing around an idea here in my head----
What would be the (negative) ramifications of setting the oil level about 1 or 2 inches higher than stock in a diff ?
The reason I am wondering - is I suspect that the pinion bearings might have been somewhat starved for oil due to the
rear axle being rolled upward from the previous owners lift kit install.

Since I am all apart- it would be pretty easy to weld in a new female pipe socket in the rear of the cover a little higher
than the stock fill plug.
I cant see how the wheel bearings could mind a higher level- I wonder- when it is rotating- does the oil get slung
outward and take on a funnel shape inside the pumkin? cant see how THAT would make it too level sensitive......

Anyone tried this idea ? would it be harmful ?

Tim

PS- when the rear axle goes back in I will be trying to lower the rear suspension (about a 9 inch lift - too much for me-
need a ladder to get in---- thinking of like 2 inches above factory) so I will have to re-set the angle the diff points- so this problem may be way less- when I tore down - the front pinion bearing was all most coming apart in my hand and the drive
plate nut was backed off about 4 turns- wondered if the front bearing had not gotten enough oil from being inclined more than
stock. The chassis has about a 6 inch spacer under the drive shaft carrier bearing ! (to keep the shaft pointing at the diff)

[PToombs]

I don't think a little extra oil will hurt. You could also install a "street ell" elbow in the hole and fill thru that. I did it with my trans and it works good.

[jethro]

Yes- I read where some people were doing that. I read that the oil could foam if it got too high.....

Got in the Detroit truetrac but not the bearings or ring gear and pinion. Probably rest of the stuff should be in by
middle next week. mean time I can do the wheel bearings.

Thanks
Tim
may try to build a pumpkin spreader in the mean time

[BobS]

I'll post a few of my thoughts here which some may agree or disagree with.

Somewhere there is an "internet opinion" that all fluid levels are always constant and level even while driving a vehicle. Using logic it is easy to see that this is most likely is untrue. In the case of the rear differential the gear oil always sloshes around a bit in the housing.

Every time you apply the brakes the pinion bearing gets super lubed. Applying the brakes is usually while going down hill which also shifts the gear oil forward. Like wise going around a left hand turn sloshes gear oil onto the passenger side axle shaft seal and bearings. A right hand turn yields the exact opposite reaction to the drivers side. There are very few highways out there that are built perfectly level due to water drainage issues.

The fill plug is located in the rear differential cover that was engineered to compensate for the above mentioned sloshing actions. It is also calibrated to allow for gear oil expansion whenever the gear oil reaches operating temperature. Ever notice that if you cold fill it to the opening it will then drip out if you check it after the oil has reached operating temperature?

Also a few years ago, I believe that on this forum or another Dodge forum there was a discussion about problems with rear axle shaft seals leaking. IIRC, one of the end results was to slightly under fill the differential to cut down on the sloshing effect on the axle seals. Also remember that new replacement seals will still be required to locate against the same worn axle surface where the old seals touched. Keep in mind most of our trucks are now eligible for an antique registration plate or will be within a couple of years. There are likely very very few of our trucks out there that do not have worn sealing surfaces on the rear axles.

I have personally selected to run the gear oil level about 1/4" to 3/8" below the fill plug opening COLD ever since this previous discussion on gear oil levels and the relationship to axle seal leakage. I have no rear axle seal leaks or pinion bearing failures to report while using this method.