Subject: [TR] Accessory power in +ground TR3

From: "Rick" <[email-masked]>
Date: Fri, 13 Mar 2015 16:25:21 -0500

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I installed an isolated power take-off point on my positive-ground Norton in
order to use newer accessories, like gps. After a few short trips sweating
bullets that I would accidentally brush the two chassis's against one
another (this is a tow-truck level catastrophe waiting to happen) I gave it
up and converted the Norton to negative ground, like the rest of the
automotive universe. I converted my TR3A during the original restoration.
Save yourself a lot of anxiety and convert your TR to negative ground; there
are several good posts in the archives. The original TR3 harness uses black
for chassis ground. Red is used for headlights and taillights, so there is
minimal ambiguity with the red (hot +12v) cables used in after-market stuff.
Job takes much less than a day. Might as well replace the generator with a
decent (and cheap) alternator while you're at it, if you're serious about
long trips.  If it were me (and it was), I'd also replace the starter with a
modern geared unit; the old starters give it up when the car is hot.     

Rick in Seattle

1960 TR3A

1972 Norton 730 Combat

1975 Norton 850 Mk3

1970 BSA 441 Victor Special

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<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>I installed an isolated power take-off point on my =
positive-ground
Norton in order to use newer accessories, like gps. After a few short =
trips sweating
bullets that I would accidentally brush the two chassis&#8217;s against =
one
another (this is a tow-truck level catastrophe waiting to happen) I gave =
it up
and converted the Norton to negative ground, like the rest of the =
automotive
universe. I converted my TR3A during the original restoration. Save =
yourself a
lot of anxiety and convert your TR to negative ground; there are several =
good
posts in the archives. The original TR3 harness uses black for chassis =
ground.
Red is used for headlights and taillights, so there is minimal ambiguity =
with
the red (hot +12v) cables used in after-market stuff. Job takes much =
less than
a day. Might as well replace the generator with a decent (and cheap) =
alternator
while you&#8217;re at it, if you&#8217;re serious about long trips. =
&nbsp;If it
were me (and it was), I&#8217;d also replace the starter with a modern =
geared unit;
the old starters give it up when the car is hot. =
&nbsp;&nbsp;&nbsp;&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>Rick in <st1:place w:st=3D"on"><st1:City =
w:st=3D"on">Seattle</st1:City></st1:place><o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>1960 TR3A<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>1972 Norton 730 Combat<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>1975 Norton 850 Mk3<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>1970 BSA 441 Victor Special</span><o:p></o:p></font></p>

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** [email-masked] **

Archive: http://www.team.net/archive

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From: "Randall" <[email-masked]>
Date: Sun, 15 Mar 2015 08:42:25 -0700

>  Just handling 
> the GPS , and having the case briefly touch metal was enough 
> to fry everything. 

That would be an example of the sneak ground path I was talking about.  Carl's proposal with the second electrical system would
eliminate that possibility; and even allow the GPS ground to be connected to the original ground without ill effect.

-- Randall