> I might have talked about this before, but, I'm still confused about the brake
> light sending unit on my TR3A. I wouldn't mind one from NAPA or somewhere
> cheap since I'm not out for originality.
Last I checked, they're actually more expensive from NAPA than from TRF ! Don't
recall the application offhand, but there were several for old American cars
that would fit. Seems like maybe one was a 53 Buick and another was a Ford
pickup truck of about the same vintage. ISTR the Buick had screw terminals and
the Ford had quick connects.
But, they're only $13 from TRF and NAPA wanted $20-something.
> However, the original one I removed from the car has only three
> connections for brake lines (including the line from the master cylinder), the
> brake light switch AND a funky octagonal silver 2" tall nut that must act as a
> pressure relief valve.
There are lots and lots of places where the Haynes isn't quite right, this is
yet another one. (Same thing holds for the factory manual, but at least it has
the excuse of being printed before the changes were made, and has fewer outright
mistakes.)
> If I could do away funky nut then my unit would have
> the correct number of orifices and there would be four lines:
I think what you're missing is that there is (or at least should be) a line
connection on top of the "funky nut".
> AND don't forget the brake light pressure sensitive (how many PSI?) switch.
It's not many (psi that is), nor is it particularly critical. However, I would
NOT suggest you contemplate substituting a switch from some other application
(like an oil pressure switch). The brake circuit sees some very high pressures
(1000 psi is possible) and if that switch blows apart, you have no brakes.
> Could some explain this unit to me?
The "funky nut" is a residual pressure valve that was added sometime after the
front disc brakes were introduced. The problem was that after "spirited"
driving, the brake pads would be knocked back into the calipers by the play in
the front wheel bearings (and the deflection of the front spindle), resulting in
a low brake pedal on next application. The residual pressure valve holds the
pads against the rotor slightly all the time, ensuring the pedal won't be low on
next application.
I didn't like the idea, so I removed the spring and plunger from inside the
valve many years ago. The factory apparently agreed, as the valve was
eventually deleted during the TR4 run.
> P.S.- Irv wrote me and said maintaince records for his 2m p1800, etc. were
> available if one simply types in "Irv Gordon" at most search engines.
Did you ever see the cover of Spy Magazine, where they showed Bruce Willis
pregnant with Demi Moore's baby ?
Not that I'm suggesting Irv isn't completely honest ... just that those
"records" don't prove anything.
http://ateros.com/pregnantmen/sightings/spy.jpg
http://www.malepregnancy.com/ (Caution, no LBC content)
Randall
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