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MG MGB Technical - How to solder?

For most of us this is probably rather a silly question, but your advice on the ammeter( don't do it!) prompted this. In my new found project, that is to do a little hill climbing, I am preparing the car thus. A battery cut out switch, I have the right piece, but was wondering the best way to connect things. Ray, you have quite rightly said proper soldered joints. This is my problem; The battery cable is huge gauge, my little soldering iron just is not 'man' enough to get it hot to solder. I really do not like the idea of just crimped joints. What is the best way to heat, without melting insulation etc, short of taking it to a 'sparky', to get the job done? Mike
J.M. Doust

Use a gas torch and heat the fitting and dip in flux, then heat the cable and "tin" with solder. Then heat and join both and fill with solder.

If your wife is amiable, use the oven top or BBQ if you don't have a plumbers torch. You can get the disposable bottles from bunnings with a cheap fitting for about $30 these days. Just don't overheat the cable as the coer will melt.
A J Ogilvie

electrical irons with the grunt to do this do exist. I solderd my earth strap using one. I just asked all the engineering companies I knew until I found one. While I was looking a contact at Smiths Aviation design centre replied that they didn't have an iron, but could run a computer analysis of the heat flows for me :-). So a bit too theoretically biased for what I wanted!
Stan Best

Just done this. I tinned everything using a gas torch; pushed the parts together; 'crimped' with a nut splitter being careful not to split the connector ferule; filled it all with solder using the gas torch. Holding the cable in a vice will take a lot of heat out of the system so there is no danger of melting the insulation.
Richard Coombs

Mike
If you go to Dick Smith's or somewhere similar and get a piece of shrinkrap tubing and slip a piece a couple of inches long up the cable first, then solder up the joint and then slide the shrinkwrap back down over the joint and shrink it on, it will look real pro. If you have already soldered it and the insulation melted a bit and you're not happy with how it looks you can stretch a piece of shrinkwrap over the fitting onto the cable/joint and then shrink it Cheers Willy
William Revit

I used a gas torch and wrapped the end of the insulation with wet cloth.
PaulH Solihull

I forgot I'd done just as William suggested. See photo.

Richard Coombs

Just remember that the PARTS have to be hot enough to melt the solder and ideally the parts should be in contact with one another. The solder holds the joint together, it's NOT the joint!
Tin, crimp and then solder. Scorched insulation is easy to replace with shrink tubing as mentioned.
Allan Reeling

J.M., I have a 3/4" diameter soldering iron that I bought in 1962 for $12. It still works great and, when it gets up to temperature, will solder even the biggest connections. Not every place carries these units, but they are still available and inexpensive, if you look hard enough. It is a very simple device with no on/off switch. You plug it in and it heats up to maximum temperature in 3 minutes. RAY
rjm RAY

You really don't like the idea of crimped joints without solder - but that is exactly what the professional auto electrician would do. The chap I watched would crimp a thick cable like a battery cable by placing the cable with the terminal on it into a V-block and then use a hammer and blunt punch to distort the terminal onto the cable, very firmly. He reckoned you got much better contact through the many strands of the cable because you were crushing them all together. My V8 MGB's cable was done like this three years ago and is no bother at all despite the heavy load placed on it by the starter.
Mike Howlett

Thanks all for all your helpful comments. I shall go and buy a butane gas torch this weekend. I am sure I had one in the garage once but cannot find it. My dad sent a lot of tools to me here in Oz from the UK, ( He is now 83.). But they are over in Ipswich in storage, I remember using his old soldering iron as a youngster, Yes Ray, it was bought in SEARS years ago in Caracas Venezuela when we lived there. It was a big 3/4 iron, my complaint then was it was frying my transistors, when I made a couple of radios! I should use my wits more often, I had the answer all the time! Thanks, Mike
J.M. Doust

I've had no problems simply inserting the cable into the terminal and *not* crimping. However both cable and terminal *do* have to be hot enough to melt the solder or you will get a dry joint. Many years ago I watched a mechanic heat up a terminal with a blow-torch till it melted solder, then plunged in the cold cable. That lasted a few months.
PaulH Solihull

This thread was discussed between 21/09/2011 and 27/09/2011

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