What you're doing is called "tinning" the wires (applying solder to the wires before joining them). For electronic projects, with stranded wire especially, I don't care for this procedure. As you say, it initially makes the bond "solder to solder" rather than "wire to wire". Additionally, the solder makes the wires "stiff" so it becomes very hard to twist them together tightly.
When I solder wires, I join them and THEN heat and apply enough solder so that it flows easily into the joined connection, and when it cools, the appearance is "shiny bright" and not "frosted" which would indicate a "cold solder joint". Also, I use a quality grade of electronic solder (which is usually a very fine wire) as opposed to the thicker "rosen core solder". Of course, you never use acid core "metal mender" solder on electrical connections.
Here's a link that contains a video that shows how I join two wires:
How To Solder - Soldering Tutorial I use heat shrink tubing to protect the join afterwards and shrink it with a heat gun (a hair dryer will work if you don't have a heat gun). If the area is going to be exposed to heavy elements (like what's under a truck), I will also paint the joint with Liquid Tape (over the shrink tube as additional protection).
Here's another link that shows various splices:
New Document The one I like for two wires is the "Western Union Splice". And, I use a soldering gun rather than a low-wattage soldering iron to join wires like this.
I don't like electrical tape. I think heat shrink tubing and Liquid Tape is far superior. I also prefer the heat shrink tubing that has adhesive inside.
Anyway, these are my thoughts. I suspect you have enough "original wire" to redo the extensions, if you want to give that a try.
- Jack