Listers,
Here is a follow-up on my recent "Out Damn Switch" post. I received a few
off-line emails on this topic, including one from Stu Brennan suggesting I
give some more specific instructions about the installation and type of
switch to use, so here goes. For the switch, I went to NAPA and looked
through about a dozen or so pages of their parts catalog and picked out a
pretty generic looking brake light switch. The part number of the one I got
is SL322. Its applications include BMW, etc. and cost me about $12. It has a
round body with two spade lugs sticking out the back and a threaded portion
at the push-button end for mounting and adjusting the position. All it
needed is a simple right angle bracket to mount directly aft of the brake
pedal. I mounted it to the under side of the cowl box, with the switch
button1.25" lower than the bottom of the box. I used a straight edge to line
up the bracket with the center of the brake pedal arm. The arm has a rounded
edge, so it is important to line it up accurately. I considered adding a
sheet metal piece to the arm using the pin that attaches the master cylinder
actuator rod, but I haven't found that necessary. It might be an even better
idea to stick a little rubber button on the end of the switch, but I haven't
done that either. In any case, this little installation will probably only
take you about an hour to accomplish.
Wiring the switch is pretty easy too, especially if you leave the original
wires going to the hydraulic switch in the harness as I did. The first thing
to do is to permanently connect the two wires that went to the hydraulic
switch together. I soldered and taped them. Then, under the dash on the
driver's side, find the bullet connector with the green/violet wire that
goes to the brake lights. With the old leads permanently connected, the
brake light should go on whenever the ignition switch is on. Pull apart the
bullet connector a see that the brake lights go off to confirm that you have
the right circuit. Then all you need to do is to make short leads with spade
connectors on one end and male and female bullet connectors on the other and
use them to patch the new switch into the circuit. Now adjust the proximity
of the switch to the brake arm. After some trial and error you will find a
position that works reliably.
As a final note, I have probably overstated the risk associated with the
stock hydraulically operated switch. I mentioned this problem to Dick Barker
today and he recalled that the chap who had the problem in Grants Pass was
using a switch with 1/8" pipe threads instead of one with the proper 3/8" NF
threads. The pipe threads just blew out under pressure. My mode of failure
was entirely different and is probably the result of some combination of
unique circumstances. Still, for several reasons, I'm glad I made the
change.
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