Board logo

joining thicker wires
mikeb - 12/12/11 at 02:18 PM

I need to join up the wires from my ignition switch to my loom.
For thinner wires I'd normally lay them on top of each other, solder them heat shrink over the top.
Is this suitable for thicker cables for the ignition?
Cheers
Mike

big-vee-twin - 12/12/11 at 02:27 PM

Crimp

mikeb - 12/12/11 at 02:30 PM

Prefer to make it permanent. Never had much luck with crimps longer term.
Surely a nicely soldered connection is going to be better?
Plus I dont' have any that size and I'm tight

big-vee-twin - 12/12/11 at 02:36 PM

Nothing wrong with crimps long term, most dirstribution cables in buildings carrying 100's amps are crimped and last well over 25 years

Soldering is fine however but I would do it with a crimp

jossey - 12/12/11 at 02:44 PM



with heat shrink on top.

should be ok shouldnt it?

bi22le - 12/12/11 at 02:50 PM

When I was doing a lot of in car entertainment I had to join thick supply wires quite often. You can get nice gold plated self insulating joining blocks. They are quite extensive so the locost sie would be to solder. I also ended up doing this quite alot because access of space was often tight.

Make sure the wire doesnot flex where is it left. As I am sure you know the wire becomes brittle just either side of a soldered joint. You dont want intermittent problems under a heat shrik that you will never find!

Good luck.

snowy2 - 12/12/11 at 02:54 PM

The trouble with soldering is that it is prone to cracking hence why the major car makers all use crimped connections. you don't need to run thick cables to the ignition switch.....use relays a bank of 45A relays can be triggered with a single 5A wire.

MikeRJ - 12/12/11 at 03:26 PM

A crimp IS a permanent connection, but not when it's done with a pair of pliers or side cutters! A crimp offers vastly better resistance to vibration than soldering and lower electrical resistance.

Autosri - 12/12/11 at 04:00 PM

At work I jus use crimps and they are fine if done right but when I used to do my car audio stuff I would crimp the cables and then heat them with a blow lamp and get some solder down the hole in the middle that way the crimp holds the weight and is still flexible at the ends but perfectly joined in the middle but for normal ignition wires I would just crimp them

craig1410 - 12/12/11 at 07:55 PM

Agree with those who say that you should crimp not solder. I used to design engine test looms for Lucas Automotive Electronics in Cirencester and the looms had lots of crimped connections in them. There were some soldered joints but most were crimped.

The key thing is to buy a proper crimp tool with a ratchet and use the correct die with the correct crimps. If you do that and of course prepare the ends properly then you will have a joint so strong that the cable will snap before the crimp pulls out. More importantly it will survive vibration fatigue for many years before breaking, unlike solder joints. I should also mention that I am trained to military standards in soldering and I would prefer a crimped connection on an automotive application any day.

See if you can borrow a crimp tool if the cost puts you off.

If you do decide to solder then a technique I've used before is to bare the ends of the wire and then just push the two bare ends into each other such that the wire cores "interleave". Then use a pair of needle nose pliers to compress the joint gently and use liquid solder flux to soak the joint before using a relatively small amount of solder with a powerful iron. If you can compress the joint nicely then you shouldn't need much solder and you can largely avoid brittleness at each side. Then use adhesive lined shrink sleeving in two or three layers to support the joint. It is imperative that you avoid any bending loads on that joint so support it with cable ties or whatever when installed.

HTH,
Craig.

mikeb - 13/12/11 at 02:38 PM

crimps it is then.

I know production cars use crimps but I only have the cheapy ones, that was really what I was refering to in terms of being a bit ropey not your OEM grade stuff.
Cheers

Mike

eddie99 - 13/12/11 at 02:40 PM

As a few people above, I crimp everything, using correct crimping tools, crimps are permanent. Just make sure you check everyone but seeing if you can pull it apart.

craig1410 - 13/12/11 at 02:45 PM

quote:
Originally posted by mikeb
crimps it is then.

I know production cars use crimps but I only have the cheapy ones, that was really what I was refering to in terms of being a bit ropey not your OEM grade stuff.
Cheers

Mike


If you take care you can effect a decent crimp connection with a pair of needle nose pliers but you need to ensure that you roll the ends of the crimp into the body of the wire. The result when viewed from the end is like a figure of eight. Another way to describe it is if you take both hands and close your fists and point your thumbs up. Then bring your palms together with thumbs pointing at your eyes and the shape of your curled up fingers should be similar to the crimps. You can ease the crimp into this shape with pliers but it takes much longer than with the correct die. Better than just using side cutters though. Also depends on whether the crimp is insulated or not as you might not be able to get at it if it's insulated.

Just make sure the resulting joint is mechanically strong - pull it hard to test. And also, think about what would happen if it came apart and shorted on the chassis. Is there a fuse to protect the live wire or will you be looking at a loom meltdown and possible fire??? Be safe!

mikeb - 13/12/11 at 03:14 PM

THe ones i have are like this.
blue Spade Terminals Male & female crimps crimp x 50 | eBay

I dont' think you can get a nice figure 8 on those.

What type to people recommend?

snowy2 - 13/12/11 at 05:28 PM

My car is wired with them and my article posted elsewhere on here recommend them. my car has done 20000 miles over 3 years with out any problems....