Copper Washer

[Bill in SoCal]

The picture is of, what appears to be, two copper washer found under the two long bolts of the transmission tower of a 1930 coupe. They look like shims, but what are they? I would have expected to see lock washers, like those under the four small bolts. Thanks for you thoughts, Bill

 

[rotorwrench]

Copper washers were normally used as gaskets and still are for aircraft spark plugs and many different types of banjo style fluid fittings. They are soft enough to squish into an uneven surface but hard enough to still act as a washer too. Aluminum is also used for this but copper can be reused if it is anealed again.