gingerprince
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| posted on 7/10/17 at 10:56 AM |
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Rewire
Hi
I'm thinking of a rewire of my MK over the winter. Never been happy with the wiring since I bought it, the builder clearly wasn't an
electrics man. Wires go under insulation tape and emerge a different colour. Wires go to the other end of the car to a loom connector, which is just
jumped and sent back to the other end of the car. The coils and other bits are wired with 2 core lamp mains cable. There's cheap b&q
connectors everywhere. There's in line blade fuses all over the place. It's just a nightmare to fault trace.
So, I intend to at least tackle the worst bits but more if it goes well. Going to get new wire, proper ratchet crimper, sealed crimp connectors etc
and a new fuse box to pull it all together.
Couple of questions for those in the know:
* I could get rolls of lots of different colours to match the existing loom but that could get expensive. I have seen a rewiring pdf somewhere
which suggested just using black wires throughout and then using coloured tags either end such as these
http://www.ebay.co.uk/itm/222640391808. Is this a good or bad practice in real terms? It reminds me of 1980s TVR using one colour wire, but if tags
are solid is this OK? I intend to Visio diagram the whole thing as I go.
* Given the relatively small amount of wires in these cars, is it worthwhile using multiple wire gauges or just use the same gauge even if it means
signal wires etc are over specced? Apart from main fuse box feeds and grounds of course.
* Any other general tips?
Thanks.
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BigMac
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| posted on 7/10/17 at 11:09 AM |
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I did this on my Westfield a few years back, provided you're comfortable with electronics (which the posts suggests you are) it's not a
difficult task.
I tried the idea of using standard wire and then tagging at both ends, but I only tried it on the front end part of the loom. Great idea, but when you
need to splice into a cable later on down the line, unless you've labelled it every 6-12 inches, you're really not going to know which is
which. This makes it a pain as you'll have to strip the covering off the loom and then trace the individual wire. Not a no go, but if you do,
perhaps think about labelling the wires up at specific intervals where you 'may' want to splice into some day.
As for using the same gauge of wire, I don't see that being a problem either, but as you say, you'll have to run it at the size of the
largest required diameter, so nothing is under-specced.
One thing I will say, is just keep an eye on costs- if you go down the route of buying decent connectors, good quality cable management and all the
associated gubbins, it gets expensive pretty quickly... In some cases, it 'may' work out cheaper to have someone make a custom loom.
Either way, good luck and enjoy!
[Edited on 7/10/17 by BigMac]
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cliftyhanger
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| posted on 7/10/17 at 11:14 AM |
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A friend works on forklifts, most of which use all black wires. He reckons it is a nightmare as the letters/numbers wear off. May not be such an issue
for you, but.....
As to wire gauge, lots of stuff like sensors, switches for relays etc only carry a very small current. So why use something big enough for a
headlight? So I think you may be better off with a minimum of 2 cable sizes, 17A and 3-5A?
The most successful home looms I have seen have been carefully set out on boards to get lengths correct.
Re crimps, do not use the blue/red sleeved type of terminals. Get the correct OEM uninsulated type (insulation boots available, or use heatshrink),
and the correct crimpers to match. They are different, not by much but makes a big difference.
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JC
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| posted on 7/10/17 at 04:47 PM |
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I had a 205GTI that had all black wire but the printed labelling had rubbed off - nightmare.
However, on my car what I have been doing is using combinations of shrink wrap at the end of each cable to code them - they are all black.....
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craigdiver
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| posted on 7/10/17 at 10:05 PM |
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As an electrical engineer I would recommend leaving as is if it is working ok and work on producing a schematic for the wiring so if a fault develops
it can be traced. This may involve adding wire markers (we call them idents). If you use decent idents they should be impervious to rubbing off or
oil/solvent damage.
If it ain't broken, fix it anyway (just because).
Building - BMW powered Haynes Roadster/442E hybrid.
Volvo C30 T5 Polestar
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hearbear
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| posted on 7/10/17 at 10:50 PM |
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As Craig said if it isn't giving you a problem then leave well alone, but if you aren't happy with it and want to replace it, the wire
numbers are what we used for many years and they were good as after a bit the colours were enough you didn't look at the numbers. Make a very
good diagram so you can reference back yourself and also put the numbers at any point where a wire may leave the main loom giving you a chance of
identifying the wire without stripping a loom down to see where it goes to just to find a number. Just be very methodical and use the old loom as a
reference. You could also buy a length of multi core numbered cable for example 40 core and this gives you a lot of fully numbered along its full
length cables Cables
[Edited on 7/10/17 by hearbear]
3.9Ltr SSC Stylus should be fun
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rodgling
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| posted on 8/10/17 at 07:48 AM |
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Lots of good ideas about constructing a good quality wiring harness here, although some of the tools and techniques discussed do require a fairly
unrealistic budget:
https://www.rbracing-rsr.com/wiring_ecu.html
I've used quite a bit of spec55 for the wires on my car, it's good stuff, very skinny compared to normal wiring and very tough. Also easy
to pull through because it's teflon. A label maker which prints onto heat-shrink would also be a must-have if I was doing this.
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ste
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| posted on 8/10/17 at 05:57 PM |
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I've made quite a few looms and recently done a rally car from scratch.
i highly recommend http://polevolt.co.uk/
I bought all the cable my the metre and used british standard colours throughout.
Unless you are making more than 20 looms in one go, there's no economics in buying cable by the roll.
You can simplify it even more using one of simtek's bodylogic control modules and get rid of all your relays and nearly all fuses.
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craigdiver
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| posted on 8/10/17 at 06:09 PM |
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quote:
Originally posted by steI bought all the cable my the metre and used british standard colours throughout.
I take it there is no requirement to follow any wire colouring standards for the SVA?. I have dismantled the BMW donor loom and used random, but
unique, colours for each circuit.
If it ain't broken, fix it anyway (just because).
Building - BMW powered Haynes Roadster/442E hybrid.
Volvo C30 T5 Polestar
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02GF74
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| posted on 8/10/17 at 06:15 PM |
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How much time and money do you want to spend?
How long have you owned the car and in that time how many electrical problems have you had?
How much does the hashed loom bother you?
You ll need almost a full strip down to rewire properly, if that is what you intend doing, then rewiring makes sense.
Buy correct gauge wire, no need to pay more and excess weight.
Vwp sell wire. Many colours and gauges draw diagram as you go on, or buy mk or generic loom.
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gingerprince
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| posted on 9/10/17 at 11:28 PM |
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Thanks all, some good tips.
Had another look at it all this evening - whilst there's some bits I still do need to tidy up, I'm going to take the advice to not
completely rip and replace what's basically working. I'm going to work through the whole loom methodically, document what I find and
replace some bits I'm not happy with along the way. There's other bits that will stay as-is, but at least I'll know what's
what for future reference. I'll end up replacing some connectors (getting rid of rusty blue things!) and re-routing/replacing a few wires where
they're particularly horrible.
Cheers.
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