[TR] brake pressure switch O-rings

[Randall]

Viton is not recommended for use with conventional brake fluid.  One report
I found said it swelled by 56% when exposed to "Girling Crimson" for 2
weeks.  Obviously unacceptable.

EPDM is the right stuff, even if MMC doesn't mention all the uses for it.  
http://www.columbiaerd.com/epdm_orings.php

Here's the same chart for Viton
http://www.columbiaerd.com/fluorocarbon_orings.php

-- Randall