Re: Bits of brass in a 32 900 differential

Posted by Owen_Dyneto On 2011/4/14 22:30:49

I thought there was some commonality to the shapes of those pieces - sure do look like remenants of bearing cages. Some of the early extreme pressure (EP) gear oils attacking yellow metal is a well-known story to most old timers. Packard did specify particular vendors and grades of some lubricants but at least in the early years of the Angleset rear I believe they always said to use "a Packard approved gear oil" or something to that effect and never mentioned a particular brand or grade. Some of the earlier EP gear oils used sulfo-chloro-phosphorus compounds as EP additives, the breakdown products of which attacked yellow metals like brass, copper and bronze. I don't think this is a valid concern anymore with today's EP gear oils.

I did pull my spare 34 Angleset partially apart tonight, the roller and ball bearings all have steel cages - don't know when that changeover took place though I suspect those bearings are original to the unit.

I don't change my transmission and differential gear oil twice annually as Packard recommended, primarily because I don't use the car much in cold weather, and of course the limited number of miles it's driven. I've been using Valvoline SAE85-140 EP gear oil for about 45 years in the trans, differential and steering gear w/o any problems.