[TR] TR4 Brake Light Switch

[Randall]

> I do have a relay on the brake circuit as I have 5 brake lights hooked up
> - was concerned that a bigger draw would kill the switch over time.

I wondered about that too, but adding relays to my current TR3 (with a
single brake light, so less load on the switch than the later cars with two)
didn't help.

I also cut open one of the failed switches, and found the black, glassy
looking substance on the contacts that I (now) associate with being fouled
with DOT 5.  I didn't find any liquid fluid in the chamber with the
contacts, but it did look kind of 'wet'.  

The original switch in my previous TR3A did survive with DOT 5 for many
years; but several replacements (including a Ford replacement from FLAPS)
failed within a year of installation.

My conclusion is that some switches just don't seal tightly enough to keep
all traces of DOT 5 from leaking past the diaphragm.

The mechanical switch gets the lights on just a fraction of a second sooner
anyway, which IMO is a Good Thing.

BTW, although I didn't try it, I believe the green wire to the original
brake switch is a separate piece from the fuse block (on a TR3, I assume TR4
is similar).  You could install a 4-way bullet sleeve at the original switch
(thus shorting across the switch) and just splice a new wire to the green
wire at the fuse block for a more stealthy conversion.  The switch at the
pedal (and the wiring to it) can't be seen unless you are laying on the
floor under the steering wheel.  It would take a really determined judge to
notice it! (Not that I care, working brake lights are far more important to
me than what anyone thinks of my modificagtions.)

-- Randall