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| Intalling fusible link or overload switch in '57 Chrysler wiring loom|
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|Since there are no fuses in the original loom I was considering putting a main fuse or overload switch on the main power feed to the ignition. i realise it would be better to put a fuse box in and fuse each and every circuit but have any of you just installed a single simple overload as some protection, what amp rating would work? |
Location: Lower Mainland BC
|I am by no means trying to dissuade you from adding items that would, in theory, add to the safety of your car. That said, you are correct there are no replaceable fuses in these old beasts. *HOWEVER*, the electrical engineers who designed the electrical systems were not complete idiots. Instead of fuses, they used circuit breakers, aka "thermal fuses" on the heavy load circuits. If the current flow on those circuits got too high, the thermal fuse/circuit breaker would open, stopping the current flow until the breaker cooled down. Then it would close again. This would repeat until the owner/driver figured out there was a problem that needed fixing and fixed it. Presunably, in the mean time, the car didn't start on fire |
Edited by 56D500boy 2019-10-20 11:19 PM
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Location: Perth Australia
|The electrical engineers WERE stupid in the way they designed the electrics in these cars. They are renowned for burning up the |
main power feed to the dash (headlight switch, ammeter or ignition switch). A fuseable link (or "slow blow" fuse) rated at 60 amps
will be sufficient to protect the main feed wire for stock vehicles, those with up rated alternator conversions may need higher.
The main feed wire (not the starter cable) will be found coming off the pos battery post, starter relay or the starter solenoid depending on your car.
The circuit protection you use should be as close as practicable to where the power feed starts from
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Location: Ontario, Canada
ram300 - 2019-10-20 9:39 PM
Since there are no fuses in the original loom I was considering putting a main fuse or overload switch on the main power feed to the ignition. i realise it would be better to put a fuse box in and fuse each and every circuit but have any of you just installed a single simple overload as some protection, what amp rating would work?
Starting in 65/66 Chrysler used fusible links in their harnesses. Back in the day, I copied what they used and installed them in all my 57/58 cars. They were a simple addition and completely irreversible. Two fusible links, one for the horn only power and the other for the rest of the car.
Email me for more info.if interested.
Location: Ontario, Canada
|Typo! I should have said "reversible" |
Location: Kalispell, MT USA
|My 64 was permanently disabled in 1977 due to an electrical short burning up the harness. The alternator terminal was accidentally grounded, and the whole thing went "POOF". I was only 13 and couldn't help my dad very much. Fast forward to last year: I replaced the harness with a 63 one. Better hi current terminals at the bulkhead. plus I added a couple of maxi fuse holders. One in the main feed into the car, and one in the wire to the alternator.|
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Location: Invermere B.C. Canada - Rocky Mountains
ram300 - 2019-10-20 7:39 PM, what amp rating would work? Thanks Owen
Well, yes, and no. If you use one circuit breaker for all the power, and something goes wrong with it or it overloads and disconnects your dead in the water, at least until it resets. You have no idea how scary it is when the headlights go out and do not come back on a pitch black back road some night.
It is probably redundant, but I would at least split the circuits and use two or three 40 amp circuit breakers at the battery with one feeding the ignition, one the headlights, and one for the rest.
Just to show off (and prove I have been there), some useless picture. And some that I have to take of '56 Plodge with a complete Dakota wiring harness installed, ask if your are a masochists.
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Location: North Australia
|Hey Owen, is this for your 300 Stick car? |
I have seen a couple of the re-settable CB's fail, so some risk there. A fusable link would look the best I recon, and easy to make a couple spares for the glove box.
To work out what amperage required, how about set up a temporary amp gauge, turn everything on then record the current draw. Add 10 to 15 amps and you will be in the ball park.
With my Imperial, I made up a new loom for the headlights using a fused double relay, and used the original high and low beam wires for the relay triggers.
Takes the load away from the headlight switch, plus gives much better voltage to the lights. This relay also just failed, made for some interesting troubleshooting (because of the auto headlight dimmer!).
Have you been driving your 300C around? You should make a video for us.
Edited by 60 Imp 2019-10-25 7:01 PM
|Nah this is for a '57 NYer I'm doing a rebuild on, it had fried the ignition circuit, not overly concerned about originality with this car. Thanks to all for the great ideas some nice/clever wiring work going on out there! |
So Steve you want me to hold a video camera while driving this manual trans, manual steer, manual brake dinosaur 300C.....yea I bet you'd enjoy that
|It's fairly easy and clean to add inline fuses at each device or main load. Some of it is protected and some is not depending on what make and model. In my opinion any protection done correctly is better than no protection. A fusible link alone will not tell you where a potential problem is but fuses at each device can make it easy in regards to trouble shooting. However you do it make it easy on yourself and anyone down the road and install in easy to find / reach / access / replace areas.|
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