Fusible link questions

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matthon

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According to the wiring diagram the fusible link wire goes from the bulkhead to the starter relay. I can find these on e-Bay, but they are not for the a-body and are too short.

Who sells the correct fusible link wire?
Or, is there a way to make one?

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I replaced mine on my 67 Dart with a 50A slo-blo maxi fuse. I carry an extra fuse in the glove box and have never had to replace it but it's nice to know I won't ever get stranded.
 
The fuse link is a chemical fuse that goes off (opens) after a sustained overload-unlike a standard fuse that goes right now! They are color coded -like "red" for the amount of current. The replacement one are short because they are meant to be spliced in the wire harness where the old one was. When replacing wires/fuse links remember that a crimp connection is only for mechanical strength you must solder for the electrical connection.At least that is what we are taught at the NASA in the classes for maned flight soldering. And use heat shrink over the splice.
Lynn
 
The fuse link is a chemical fuse

No, it isn't. It's an electrical fuse made out of wire a specific amount smaller in gauge size than that of the circuit being protected. The insulation is specially designed not to melt as ordinary wire insulation would. You may find it interesting and informative to read this 1965 SAE technical paper by Chrysler on how fusible links work, how they are specified and sized, etc.

They are color coded -like "red" for the amount of current.

No, they aren't.

The replacement one are short because they are meant to be spliced in the wire harness where the old one was.

Incorrect. The length and gauge of a replacement fuselink determine its current capacity and the delay before it opens, so both parameters must be the same as original in order to have the same protection.

When replacing wires/fuse links remember that a crimp connection is only for mechanical strength you must solder for the electrical connection.

That's not correct. A good crimp junction is superior to the average solder junction in applications (planes, trains, cars) that move and vibrate. See here, here, and here (pdf).

It's plain common sense that a good junction of either type is better than a bad junction of either type. A good crimped and soldered junction may or may not be the best of all.

Obtaining a good crimp junction requires buying a real/good crimp tool and real/good terminals (the cheapy consumer-grade "wire pliers and 250 terminals for $15.99" stuff commonly available at parts stores and discount stores are junk) but only a small amount of practise.

Obtaining a good solder junction requires buying a perfectly serviceable, decent-quality solder gun + solder and miscellaneous supplies but needs a great deal of practise.

Obtaining a good crimped-and-soldered junction requires nontrivial expense and a great deal of practise.

And use heat shrink over the splice

Yes.

Original poster: you can get a correct direct replacement for your fuselink from Bill Evans.

Circuit breakers and fuses behave differently than fuselinks — this is why fuselinks don't have straightforward amperage ratings like circuit breakers and fuses do. Take a look at this post and the links from it (and the posts above and below it in the thread), for info on replacing fuselinks with other types of circuit protection devices if that is what you intend to do.
 
Both spellings are used in Canadian (+British, Australian, South African, Irish) English. "Practise" is usually the verb -- you practise the piano, you practise medicine or law. "Practice" is usually the noun -- you got some practice in before lunch, you have a law practice. But both spellings can be used for both, which is a good thing, considering I broke the convention and used "s" instead of "c" for the noun in my post above.
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In American English, "practice" is used for both noun and verb.
 
A lot of information. I guess what I am wondering now is if replacing the fusible link with the original type is the best way to go?

It appears that if I am keeping the car's electrical stock and not adding on to it, then I can file the original fusible link under the "if it ain't broke" category, and they are not expensive to replace just waiting time for mailing.

My concern is since this is an 40 year old car, I might be leaving myself open to the risk of the fusible link burning out and leaving me somewhere- so should I consider replacing it with one from the chart and carry spare fuses?

The car's wiring was hacked up and the fusible link was simply bypassed. It was only when I got into it and reading up on it did I discover the purpose of that thing hanging from the bulkhead connector.

Now that I have sourced new and complete wiring for the whole car I will replace it all in the next few weeks- back to my concern of the old car and the potential to burn up all this wiring I spent so much time gathering.

Here is the chart from one of the links, but I am also concerned about walking into a parts store and finding someone who knows what a Hypalon Link or a MAXI Fuse is?

Circuit Hypalon Link Type MAXI Fuse Rating Circuit Wire
Alternator Feed (R6) 12 gauge (black) 160 amp (2x80 in parallel) 8 gauge (BK)
Radiator Fan (C26) 20 gauge (orange) 40 amp 14 gauge (GY)
Ignition Feed (J10) 18 gauge (grey) 50 amp 12 gauge (PK/BK*)
Ignition Feed (J1) 20 gauge (orange) 40 amp 12 gauge (RD)
ECU/ASD Feed (J1) 22 gauge (white) 30 amp 12 gauge (PK)
Direct Battery Feed (L1) 18 gauge (grey) 50 amp 12 gauge (RD/WT*)
Heated Rear Window (C13) 18 gauge (grey) 40 amp 12 gauge (BK/RD*)
Hazard Flasher (A3) 20 gauge (orange) 20 amp 14 gauge (PK)
 
Based on the information provided and:

- my car only has 1 fusible link in the wiring diagram
- I will not be protecting other circuits by splicing in additional fusible links
- I will be replacing all of the wiring, some new some used but very good condition
- I currently do not have the fusible link, (the red wire from the starter relay)
- since I am not a electrical wizard

I came to the conclusion that I should use a Maxi Fuse, as they are readily available, (no ordering, no waiting, I can carry a few with me and even replace the extras quickly), and no splicing required to replace.

The best I could come up with after much research, is to use a 20 gauge wire for the entire length of the red fusible link wire in the diagram, and put a 40 amp Maxi Fuse in it.

Any comments or input?

I read a ton of information- but sometimes you get to a point where you have read too much and/or you are reading the wrong information.
 
The best I could come up with after much research, is to use a 20 gauge wire for the entire length of the red fusible link wire in the diagram, and put a 40 amp Maxi Fuse in it. Any comments or input?

Yes: That's wrong. A 20ga wire will burn up quickly; before it does that it'll cause severe voltage drop and nothing electrical in the car that draws more than a couple of watts will work well, if at all. Don't know where you got the idea a 20ga wire is needed. If you are replacing a fuselink with a fuse, you pick a fuse holder that has the same gauge wire as the rest of the line you're putting it in.

Also not sure how you wound up picking a 40A rating for your fuse.

(Me, I would vote for putting in the correct fuselink.)
 
OK, thank you, will do.
I definitely passed the point of understanding to confusion- I don't know where I got that either, too late, need sleep.
 
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