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535i Andrew

Making up wiring looms - trailer

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I am going to upgrade the filament bulb clusters on my trailer to some nice LED ones.  And being LED I need to fit ballast resistors in each bulb circuit as my car just makes them all flash quite spectacularly, so I need to chop up trailer cable to fit the resistors in parallel, no issue there but I then want to tidy up the wiring by running it in something or wrapping it in something.

 

I've found some of the cloth tape stuff used in car looms.

 

http://www.ebay.co.uk/itm/25m-Meter-x-19mm-Tesa-Adhesive-Cloth-Fabric-Wiring-Harness-Loom-Tape-Cable-Roll/151946400289?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2055119.m1438.l2649

 

Or or should I use more waterproof stuff as it's going to be low to the ground exposed on the underside of the trailer taking the full spray from the car.

 

I've found this stuff which I've used before. I can seal the ends with a dod of silicon.

 

https://www.ebay.co.uk/itm/Flexible-PVC-Cable-Sleeving-Tubing-Wiring-Harness-Black-All-Sizes-Lengths/253005704845?ssPageName=STRK%3AMEBIDX%3AIT&var=552053117213&_trksid=p2055119.m1438.l2649

 

Any thoughts or experiences making up replacement looms on cars?

 

Thanks

Edited by 535i Andrew

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I thought the resistors got quite hot so needed to be mounted on a metal surface? I wouldn't fancy chopping up the cable but would rather fit it inside the light unit if at all possible. Something like this?:

https://www.westerntowing.co.uk/acatalog/load-ballast-resistor-for-LED-lights-EL3822B.html

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Hi Andrew , I frequently  make and repair wiring on aircraft . If your in line resistors are exposed I'd suggest covering them in heat shrink , most looms we make up are tied with lacing cord every few inches and you may want to look at spiral wrap which gives reasonable protection from chafing and is easily removed if problems develop in the future 

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8 hours ago, xraySpex said:

Hi Andrew , I frequently  make and repair wiring on aircraft . If your in line resistors are exposed I'd suggest covering them in heat shrink , most looms we make up are tied with lacing cord every few inches and you may want to look at spiral wrap which gives reasonable protection from chafing and is easily removed if problems develop in the future 

 

I used some fantastic high shrinkage, adhesive lined heatshrink, which will prevent any water ingress, and also means you can fit it well over large connectors, and small wires, and it will shrink down to be tight over both items.

 

Link: http://cpc.farnell.com/pro-power/hs401/heatshrink-sleeving-4-1-6mm-1/dp/CB10013

 

I first used it on a rover 75 to seal the connections to a new fan speed resistor for the radiator fan, which is very exposed.

 

 

 

 

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CPC Farnell are great for electrical supplies, free postage on all orders (or used to be) and often you can use some modifications to the web link address to get further discounts, ill try and find the link to that method if I can.

 

 

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Thanks lads

 

The resistors will be mounted to the chassis of the trailer to disperse the heat.  I have bought similar to your link @whiskychaser but a bit cheaper.  LED Light unit is sealed and there really isn't much room on the trailer to fit the light units so the resisters can be mounted within a metal channel that is one of the cross members.  I actually have one ballast resister already fitted to the trailer masquerading as a fog light as the Westfalia wiring instructions state in order to make the Westfalia towbar wiring loom fitted to my dads F10 detect the trailer it needs to detect the resistance of a 21W fog light bulb.

 

Happy enough to chop up the trailer cable to make solder connections to the resister which will be heat shrinked. I was thinking about heat shrink so I'll have a look at that too @Abbadon thanks.

 

Old cracked light unit and no room next to number plate or frame of trailer.

 

DSCN3541.jpg

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If you've got your electrics sitting in a channel Andrew , you might want to consider potting them in some hi temp rtv ( silicone sealant) as well as heat shrink . But decrease the area well before hand .

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Thanks

Its a channel that sits like a C shape facing rearwards so its always bone dry and I will fix to the vertical part of the C shape, so water can't actually pond in it but only really be subject to a mist I would imagine.

 

Meant to add its not the channel shape that the light cluster and number plate fit into ( that you can see in the photo) but a smaller cross member further forward in the trailer under the floor.

Edited by 535i Andrew

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For future re for others:

 

resistors here: https://www.amazon.co.uk/4pcs-6ohm-Load-Resistor-Signal/dp/B008KXJS8Y come with flying leads etc..

 

or here: http://cpc.farnell.com/welwyn/wh50-5r6-ji/resistor-ww-50w-5-5r6/dp/RE03491 for anyone in future looking for lower price. CPC ones you will need to add leads and heatshrink etc.. but if you have those in stock that's best price most likely.

 

 

Pictured is the power resistor I was installing, (see attached), the connections were very broad compared to the wire OD (even though it was pretty chunky wire to carry the current). Not shown particularly well in the photograph but I have used it on other applications since and no water has managed to breach the adhesive barrier so far.

 

Andy

 

 

20140819_135423.jpg

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15 hours ago, Abbadon said:

CPC Farnell are great for electrical supplies, free postage on all orders (or used to be) and often you can use some modifications to the web link address to get further discounts, ill try and find the link to that method if I can.

 

 

 

Minimum order £5 for free postage now.

 

I've got a trailer to sort for someone prior to delivery oop north; first, bin the perishing crossply tyres - have found some part-worn 195/70 x 15 van tyres for it. Then in an ideal world, the trailer needs to be put on its back so I can inspect the chassis underneath, inspect the wiring and most importantly, look at the mechanical braking system and repair/adjust as needed.

 

My friend has bought new lamp clusters for it (which she can fit!) but in my view I see nothing wrong with sticking with filament bulbs: I can't remember the last time I changed any bulbs on my trailer (maybe one in 20 years) and even on the car it's only ever been headlights, due to using ultra-bright bulbs.

 

What pisses me off is this cult of LED number plate bulbs that seem to throw an inordinate amount of white light back towards a following car, and almost obliterate the plate itself...

Edited by e60neindanke

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Yeah mine will be going on its back for the fit out.  I will need to flip it over on my driveway then get someone to help me lift it back into my garage so it can be worked on.

 

I was behind a Fiat t'other day and the two bumper mounted number plate lights did more shining backwards than onto the number plate.  I couldn't decide if it was due to a poor quality retro fit, someone had hit the back of the car and deformed the bumper of it was just Fiats build quality.

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On 11/14/2017 at 7:39 AM, Abbadon said:

 

I used some fantastic high shrinkage, adhesive lined heatshrink, which will prevent any water ingress, and also means you can fit it well over large connectors, and small wires, and it will shrink down to be tight over both items.

 

Link: http://cpc.farnell.com/pro-power/hs401/heatshrink-sleeving-4-1-6mm-1/dp/CB10013

 

I first used it on a rover 75 to seal the connections to a new fan speed resistor for the radiator fan, which is very exposed.

 

 

 

 

 

 

Looking into this stuff, what did you use to shrink it?  I've only really done short lengths before and used a lighter or the back of my soldering iron very carefully, but a long length would be a bit more tricky with a soldering iron.  Heat gun?  

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10 minutes ago, 535i Andrew said:

 

 

Looking into this stuff, what did you use to shrink it?  I've only really done short lengths before and used a lighter or the back of my soldering iron very carefully, but a long length would be a bit more tricky with a soldering iron.  Heat gun?  

 

As you say, for short bits I often use the slightly cooler bit of the soldering iron,  I use my heat gun for longer lengths , I think it shrinks usually on the cooler setting on mine.

 

 

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I have a mini blowtorch that came with a small fitting that heats up, and draws air past it, turning the blowtorch in to a heat gun, I don't know if you can buy an attachment to do the same on a larger blowtorch - assuming yours is the plumbing type item?

 

You'll only really  need to use heat shrink near splices/joins, and at terminations etc.. I wouldn't think you will need cover the whole loom with it, that would be quite costly, especially for adhesive lined stuff.

 

 I cant see you needing big lengths really. You could probably get away with heating the underside of a chunk of metal and holding the heat shrink hear it, using the radiated heat from the metal., if you want to avoid using the soldering iron method or open flame near the wiring.

 

 

 

 

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1 hour ago, 535i Andrew said:

Yeah mine will be going on its back for the fit out.  I will need to flip it over on my driveway then get someone to help me lift it back into my garage so it can be worked on.

 

I was behind a Fiat t'other day and the two bumper mounted number plate lights did more shining backwards than onto the number plate.  I couldn't decide if it was due to a poor quality retro fit, someone had hit the back of the car and deformed the bumper of it was just Fiats build quality.

 

Or all three.

 

Seriously, those LED plate lights are a bloody menace. Surely a car should fail its MoT on them?

 

A hot air gun as used for paint stripping can be used to shrink heat shrink, but they're a bit big for the job. In the past, for small joints a soldering iron held very close did the job, now I have one of those very expensive Weller heat guns (bought cheaply off the Bay). My gas soldering iron has a hot blow attachment which I use both for heatshrink and surface mount rework with solder cream. Is this a bit out of budget?

http://cpc.farnell.com/iroda/pro-50k/soldering-iron-gas-30-70w-kit/dp/SD01107?MER=sy-me-pd-mi-alte

 

There's a whole range of Iroda stuff, perhaps mix and match to suit your requirements?

 

As for looms: try spiral wrap, or expandable sleeving. You only need HS sleeving at joins/terminations as @Abbadon has said, but spiral wrap will give you some mechanical protection and you can lead wires out along its length. For comparison, my trailer has steel conduit running along the drawbar, it then breaks out into two cables running into each light cluster. The number plate is lit by a chrome Mini/Morris Minor type numberplate light connected via a 1/4" jack plug into one of the cluster housings which allows me to remove the tailboard; my lights are high up at the side, you see.

Edited by e60neindanke

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These came today.

 

image.jpg

 

6.8 Ohm 50 Watt resisters to fool the car into thinking that the trailer has the equivalent of 21W bulbs. Waiting for the slow boat from China to bring me 28 ohm ones for the 5W side light bulbs.

 

Bought from eBay.

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I did a similar project on a friends trailer few years ago, we fitted resistors in aluminium electronics project box (lots of diferent sizes on ebay) and sealed it with rtv silicone. We attached resistors along the bottom of the box so it acts as a heat sink and attached box at the front of the trailer. Cable goes in the box and much thinner cables are going from box to led lights. 

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Flanged mounted box, ideal, would need to get some holes drilled and grommets for cable entry but that's o.k.

 

https://www.ebay.co.uk/itm/FLANGED-DIECAST-ALUMINIUM-ALI-BOX-for-electronics-project-wall-mounting/112639131527?hash=item1a39d0bf87:g:qaEAAOSwz~pZ-FdY

 

Also gives a clue for me to look up RS components website as a source for other sized boxes.

 

Which is still well cheaper than this job!

 

http://www.rydertowing.co.uk/products/trailer-adapters-led/adapters-led

 

 

 

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Andrew, I used this Tesa 51026 tape in my engine bay when I installed the repair sideview camera cable: https://www.ebay.co.uk/itm/TESA-51026-19mm-x-25m-High-temperature-abrasion-resistant-wiring-harness-tape/121857267995?epid=2254325024&hash=item1c5f42591b:g:ELsAAOSwGotWi5j7

It is specific for engine bays and is heat, petrol and oil proof and isn't the cloth Tessa tape that you use on internal wiring harness but I do have that too.

Edited by Matthew Ashton

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