Gear oil for Diff using Phosphor Bronze washers

[maineSS]

I checked, and the gearset is a hypoid spiral bevel, 5.83 ratio (4.89's were available, but rarely ordered). It seems the corrosivity question is temp- related, but finding out what the temp existing between the faces of the bronze thrust washer and the spider gear is would be quite a challenge. Gear oil temp would not necessarily be the same.

 

[Jeff_in_VABch]

Where is that washer in the differential? EDIT: just saw you said behind the spider gears. I dont see an area that is subject to rotation, loads and compressed between steel on both sides developing any corrosion.

I would likely not worry about it too much. I would also think some of the manual transmission rated gear oils would be soft metal safe. Redline NS or MT varieties.

 

[tdi-rick]

Originally Posted By: mechtech2

A hypoid gearset IS spiral bevel. One version.


Generally in my world a centreline spiral bevel CWP is called just that to easily differentiate it from a hypoid offset pinion.

 

[tdi-rick]

Originally Posted By: maineSS
I looked at the ASTM D-130 part of the "Automotive Gear Lube Study" (Copper Corrosion Test), and see that NONE of the tested oils pass the 1a classification- which is what I'd want. Also, there's no mention of the type or percentage of EP additives each oil has, which makes the corrosion data difficult to evaluate. I'm assuming these are GL-5 oils- as the classification isn't mentioned, either? Otherwise, it's a good writeup of testing methodology.


What's wrong with a 1b pass ?

Most all dual rated GL4/5 manual trans/transaxle fluids have a 1b copper corrosion test pass and are fine for use in sycnhro 'boxes with bronze synchros.

I've never had problem with them, one gearbox I have has over 400,000km on it using these fluids and still shifts flawlessly.