Gear Lube and Bronze/Brass Redux

Posted by Pat Brothers On 2012/8/21 1:32:59

I know the idea of modern gear lube, yellow metals (brass/bronze), and correct gear lube weight has been flogged to death.

I am particularly interested as it relates to my '29 626. Is there any yellow metal (brass or bronze) used in bushings, thrust washers, or spacers in the transmission or differential? I realize I do not have synchros, so there is little risk with using a GL-5 Gear Oil. Modern GL-5 gear oil is supposedly non-corrosive to brass or bronze. Corrosion is not the problem.

Information I received in an e-mail from Richard Widmer (http://www.widman.biz/Corvair/English/Links/Transaxle.html) explained "As for the GL-4/GL-5 issue, the GL-5 covers and surpasses the GL-4 ONLY in EP protection. They are not the same and are not interchangable. Most gears oils of 40 years ago had lead based EP packages. Today they are Sulfur/Phosphorous. The GL-5 has twice the sulfur/phos quantity as the GL-4. Sulfur/phos works by chemically forming a sacrificial surface on the surface it is to protect. That (black) covering wears off and forms again to wear off and form again. On steel that is fine. On soft metal (brass, etc) it peels off a layer of the soft metal. Not really visible to the eye (that can only see >40 microns) but shows up as worn area over time or in oil analysis. So if a differential or transmission has brass or other soft metals (synchronizers, forks, or shims) you probably want to stay away from GL-5. If it is all steel, GL-5 is fine and will provide better anti-wear."

So, is there any brass/bronze in my '29 Packard?

Thanks for your help.
Pat