Sam, I had a similar frustration when I tried to overhaul the PDWA in my
early 1969 TR6. My car wasn't suffering from brake locking, only messy
brake fluid leakage at the switch. I assumed that because mine is such an
early car that the valve was completely different from the later ones. I am
also aware that there are at least two other variations of the device, each
with different seals and bore sizes. I was unable to obtain o-rings of the
correct size, so I made the decision to make my PDWA non-functional yet
stock in appearance. I completely disassembled the PDWA and measured the
bore. I found a tap size that would work in the bore and tapped the bore to
accept two hex head set screws - one on each side of the switch. I read the
product information available on Locktite "red" (the stud and bearing mount
type) which said that it is supposed to be unaffected by brake fluid, and
also re-verified the info on the company website. Feeling confident that
brake fluid wouldn't dissolve the Locktite, I coated the setscrews with red
stuff and installed the setscrews in the PDWA bore with a long reach allen
wrench. I've had my modified PDWA in place for at least three years and it
doesn't leak a drop into the center cavity where the switch screws into.
The only downside is that my idiot light won't come on if I lose pressure on
one side of the brake hydraulic system. But, it seems to me that the huge
reduction in stopping power would also be an indicator!
Rex Townsend
Bainbridge Island, WA
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