[TR] Brake light woes

[Geo Hahn]

On the subject of brake light switches... this is the mechanical switch I
added on my other (non-TR) British car:

http://www.amazon.com/dp/B000E5DILY/ref=pe_385040_30332200_pe_309540_26725410_item

I left the hydraulic switch in place (which has not failed despite my using
DOT5) and added the above switch with a simple metal bracket in the
footwell operated by pedal arm movement.  I had no problems with the
hydraulic switch but do like that the mechanical switch operates the brake
lights with only the slightest pedal movement - which may happen well in
advance of serious braking.

Looking at the TR3A pedal box I think that same switch might fit into the
hole in the front lip of the box to be actuated by the upper tip of the
pedal arm (very similar to a TR4 switch).  Otherwise, an interior bracket
may be needed.

Yeah, I know the usuals carry mechanical switches but I have heard mixed
results with those (esp the white plastic version) whereas this metal
version has been used by quite a few LBC owners with success.

Geo


On Fri, Jun 13, 2014 at 4:37 PM, Randall <tr3driver at ca.rr.com> wrote:

> > Of course, this is assuming the switch is new, which is an absolute must!
>
> So, you have to replace the switch every time you use the brakes?
>
> I've used DOT 5 for several decades now, and I love it.  The original
> brake light switch in my previous TR3A (which was converted in 1985 or so)
> lasted a long time, but eventually failed in just the manner described.  It
> would still work if the pressure was high enough, but the pressure required
> kept getting higher and higher until even a fairly hard stop would not
> light the brake lights.  Not a Good Thing.
>
> Several replacements from various sources (including a repro switch from
> Moss and a Ford replacement from FLAPS) went the same way in fairly short
> order (less than a year for each one, some in only a few weeks).
>
> Changing to a mechanical switch solved the problem permanently.  Well,
> almost permanently.  I did have one problem where the reservoir was leaking
> a tiny amount, and the fluif ran down the pedal and got into the switch ...
> causing a similar failure in a mechanical switch!  The moral seems clear,
> DOT 5 and switch contacts do not get along!  A post-mortem on the switch
> showed moisture along the shaft, which felt like DOT 5, and a hard black
> substance on the contacts, which I now believe to be silicon from burned
> DOT 5.
>
> But having been pushed into it, I do rather like having brake lights that
> come on _before_ braking starts, rather than after.  With the mechanical
> switch, they come on as soon as I put my foot on the pedal, instead of
> waiting until the pedal has moved far enough to build pressure in the
> system.
>
> Randall
>
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