In message <
[email protected]>
"Steve" <
[email protected]> wrote:
> "Tom Woods" <[email protected]> wrote in message
> news:[email protected]...
> >
> > I've looked at their looms for series vehicles before, and their loom
> > will work out more expensive than making my own.
> > I want so many customisations that i might as well do my own in a
> > way!. I'm fitting fuse boxes and relays where they wernt before and
> > building in a lot more stuff than is stock.
>
> Put in some over-capacity on the permanent live and switched live loom.
> Once you get into the "I'll add this and that" scenario it's easy to run out
> of live terminals to feed everything from and you'll end up having to splice
> into feeds that you've already neatly fitted. I know! Some sort of live
> bus-bar for both permanent and switched might never get used, but as sure as
> sh*t stinks you'll discover that you need another live when you haven't got
> one easily accessible.
>
> Steve
>
>
Putting on my ex-Wiremans hat..... and ex-Rists hat too...
Vehicle harnesses are not simple things, as designed for vehicles,
even for basic harnesses like Series/101's etc. There's splices
and centre-taps all over the place, and it's not just a case of
"ah! there's 12V there so I'll tap into it", a lot of thought
and sums go into dealing with failure modes, current ratings and
not starting fires etc. In fact vehicle harnesses are unique in
allowing more that 2 cables on a terminal and that sort of thing
- if you did that on control cabinet you'd be shot, possibly after
being sacked....
I'd start with a schematic of your vehicle on paper, and start
"at the corners", working back, via the dash, to the battery/
alternator. As you progress you can add up currents etc to
decide on which size cable to use, or if another seperate
feed/earth is required. Ideally you need to allow for water etc
causing short term shorts and crossovers between circuits, but
that's probably over the top for what you are wanting to do.
There are some legal things that you might like to take into
account, such as a single failure should not cause all the
lights to go out (diagonal opposite corners should remain
illuminated) etc
When you get back to the dash, you can work out which switches
can be fed from where, and after a few interations you should
end up with (notionaly) one lead to the battery/alternator.
Getting the cable lengths right is never easy, not least
as you have to remember to leave slack to allow for vibration,
re-fitting of units (bulbs etc) and avoiding chaffing and
heat. Until you've built the first one! Again though, starting
"at the corners" and working back to the dash, building the
harness (cables in and out and all about) as you go with
"definately over length" cables will avoid embarassing moments.
OK, so you will waste quite a lot of cable by the time you
get to the dash as it's a one-off, but then when you buy more
than a few metres it's often cheaper (or more cost effective,
anyway) to buy a reel. Idealy, each cable sould be a different
colour/tracer combination, but that's not practical even
on a small harness, so the un-attached ends should be marked
with labels (a pain in the bum) or idents which indicate where
they came *from* (not too).
Use proper terminal crimps, fited with a proper crimping tool
(widely available these days for not much money) - *never* use
Scotch Locks...and don't solder anything. A proper cable stripper
will save a lot of grief later. Avoid using ty-wraps to hold
you new harness together - use sprial-wrap or split convolute
tube if at all possible and/or harness tape.
It sounds like a load of grief, but if you plan it well it's
not that bad a job, but pretty time-consuming. The harness is
the first part fitted to a body in the factory, obvioulsy
much easier to do, but retro fitting isn't that bad [1].
Richard
1[1] excludes Bentley's, Range Rovers and the like - it
takes two people just to lift some of the harnesses fitted
to the likes of those vehicles.
--
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