Rear Diff oil spec?

[kevin p]

My Ex's rear end slides in the wet when it hits a bump. I read a 'post' about the fifth shock and/or the rear diff could cause this.
I know the diff has a friction modifier and other members have suggested an oil that dosn't need any.
Just wondered what other members use and if they have the same problem.
What is the friction modifier for?
Thanks Kev.

 

[PHaTGRoB]

Hi Kev. I bought Lucas Oils 75/140 Synthetic Gear oil via eBay from Dukeries Oil in Worksop, Notts. The threads on here said that this oil didn't need a friction modifier so I went with that advice. I got it to make sure I had some if required but on checking the diff found it wasn't needed as the oils was clean and full and the diff works OK. However, I plan on using it in the summer when I may change the diff oil just in case.
The rear differential on the North Face is a limited slip unit that contains a series of adjacent rotating discs. When these spin at different speeds (i.e. say when only one rear wheel is turning) the oil between warms up and then thickens to the degree that it "locks" the plates together, causing both wheels to turn at the same speed. with some oils, a friction modifier enhances the ability of the il to do this. The synthetic 75/140 does not need additional friction modifier as the oil was formulated specifically for this purpose.
Axle tramp of a live axle can be caused by the limitied slip diff not working properly and allowing one wheel to spin. Hope that this helps. GRoB.

 

[kevin p]

Thanks GRob. I couldn't have wanted a better reply. Cheers mate.

 

[PHaTGRoB]

No problem Kev.

 

[Bronco2]

The synthetic 75/140 does not need additional friction modifier as the oil was formulated specifically for this purpose.

ou ouhh .. Nope..

you could use a 75w140 but you need friction modifier..
i would suggest Liqui Moly LS75w140 as ready to go ... Oil..

you would destroy your slip clutches rapidly.. if you go without modifier..

and.. i would open it and rebuild the clutch package if the axle slips...

my opinion..