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' (0115 9305454) who are always helpful and prompt with supply. OK if you're in the UK I know - but I'm sure you foreign brethren are able to sort through a local or automotive directory to source some place suitable for you.
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?