[TR] "More reliable" sidescreen brake pressure switch for DOT5/silicone?

[Don Hiscock]

Harley-Davidson used DOT5 silicone brake fluid in their motorcycles from
the mid 1970s until the mid 2000s, when ABS started coming in.  The current
H-D brake pressure switch is reportedly backwardly compatible to any brake
fluid.  P/N 72023-51E is likely on any local dealership's shelves for about
$35 and comes in a kit with two new 025 quick disconnects.  It's made by
Bitron in Italy and uses the same 1/8" NPT threading as the original.  It
mounts with a 17mm wrench/deep socket, compared to the 7/8" hex on my
TR3B's original.  (Earlier versions with the same H-D P/N but lower
alphabetical suffixes were made in USA and were larger hex.)

For now, I'm back in the brake-lighting business.  Thanks to those who
suggested various mechanical switch conversions, but I'm trying to stay
closer to original with the car.  We'll see how this works out.  Assume,
hearing nothing to the contrary, it's workin' fine.

-- Don
1962 TR3B TSF202L




On Sun, Sep 7, 2025 at 8:08 PM Don Hiscock <don.hiscock at gmail.com> wrote:

> I converted my TR3B to DOT5 three years ago.  I've been waiting for the
> silicone oil to get into the pressure switch and cause it to quit working.
> That time is here.
>
> Yes, I could convert to a TR6 mechanical switch actuated by the brake
> pedal lever.  I may end up there.  But it's fun to keep this car as
> original as I can.  Is any one supplier's or source's brake pressure switch
> any more reliable than the others around DOT5?
>
> It was a nice day the other day, so the TR3B made the drive to the
> village mailboxes now that I"m living in northern New Mexico.  Forty four
> years last month that I've owned this thing.
>
>
> https://photos.smugmug.com/photos/i-QRBNGvw/0/KvPKhzkvQRPj3kgscg4GSP4mLXMMpmfG2cqzZbBW4/X5/i-QRBNGvw-X5.jpg
>
>
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