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Electrical - Terminal fixation |
12 December 2002 Update December 2007 |
Despite having spent something in the order of 26 years delving into all
things automotive and some 24 of those concentrating a great deal on the Mini,
I have never assumed I know it all. In fact I'm very much one of those to
support the 'you never stop learning' theory. My latest endeavours to get out
racing again have caused me to look at all things connected (sorry - pun) with
racecar preparation - the wiring loom being one such item.
I decided to canvas everybody I knew that was involved with electronics
and electrics to any degree to see what the latest state of ply was concerning
fixing terminals to cables. 'To solder or not to solder, that is the question'.
All my previous racecars (last one built about 14 years ago) had all the
terminals carefully soldered on. It used to take me ages; taking a remarkably
long time to become proficient at it - largely because of the 'not too hot'
soldering iron I'd purchased to do the job. One of my electronics specialist
friends pointed out I'd probably get just as good a result by farting on the
joint as I would with the iron I'd bought. Very kind I'm sure. The investment
of a small fortune in a proper soldering iron soon had me sticking terminals to
cables in a seriously rapid fashion. The count was coming down about 60% in
favour of simply crimping the terminals on. The other 40% interestingly was
made up of mostly 'older' (more learned?) electrical/electronic types.
Considering the arguments for and against proffered by all and sundry, the
opinions that really swung it for me (and my enquiring mind) went down to
mainly two folk - one who designs/manufacturers and trouble-shoots electronic
control systems in the manufacturing and test equipment industry, the other
works for a prominent formula one team. The main reason for my decision about
this was the fact the fruits of both their labours are used in the same hostile
environment that my racecar will see - prolific vibration.
The result is the terminals will simply be crimped on to their
respective cables. Why? Apparently soldering any electrical joint will make a
good watertight connection, BUT will make it somewhat brittle. In hostile
environments that see a lot of vibration this brittleness will eventually
result in the cable/joint fracturing. Not good since on a race-car this means
no electrical connection varying in severity from a malfunctioning brake light
to an engine that stops dead as the coil wire breaks off… Not funny when your
at the sharp end of thirty or so racing Minis fighting furiously for the lead
into the first corner at the start of a race! Yes, this happened to me at
Snetterton in my Miglia many moons ago. Frightening. Fortunately everybody missed
me as I rolled slowly off the circuit. Thanks guys. And I thought it was my
crap soldering capability.
A crimped joint, on the other hand, retains sufficient flexibility to
all but eliminate this occurrence. The trick is to use proper, quality crimping
tools for the various terminal types available. Not a problem for me since I'm
a firm believer in investing in quality tools and have accumulated all the
relevant crimping equipment over the years. And the use of decent quality
terminals of course. I buy all my stuff from a company called 'Vehicle Wiring
Products' www.vehicle-wiring-products.co.uk (0115 9305454) who are always helpful and
prompt with supply. OK if you're in the
Where soldered joints are a must, this vibration fracture problem can be
eased to some extent by the use of RTV silicone. A dab of this on the joint
helps to absorb some of the vibration, consequently prolonging the life of the
soldered joint. My formula one friend informs me this is how they treat the
printed circuit boards in the myriad of ECUs used on an F1 car. Interesting
innit? But where using silicone rtv on
soldered joints it is essential to use a non-corrosive type such as Dow Corning
type 738.