580c Starter Circuit Wire Guage

[frankdb]

I'm working on fixing up an old 580c that we recently purchased- which is especially challenging because the backhoe is located at our cabin, which is 3 hours away. One of the prior owners had pretty much removed/cut most of the wiring. It has a mechanical oil pressure gauge and in order to start the machine, you need to jump the starter solenoid with a screwdriver or wire.
I'd like to re-wire the starter circuit, adding back in the starter button, 40amp breaker, and neutral safety switch. My question is, what wire gauge should I use? From the wires that were left on the machine, it seems like they were really small...maybe 18 or 16 gauge. But the starter circuit has a 40 amp breaker in it (see attached) which would lead me to beleive I'd need 12 gauge or at least 14.
Does anyone know what wire gauge I should be using for the circuit?

 

[franklin2]

12 gauge would probably work but I would use 10 if it's not too hard to get. All OEM's scrimp on wire size to save pennies on vehicles and machinery. A little bit larger wire will help get rid of voltage drop.

 

[Tinkerer]

12 gauge.
There no need for the start button if the starter switch has the start position in it.
If the starter switch that you have is the Case OEM then you need the button connected into the circuit.

 

[frankdb]

12 gauge.
There no need for the start button if the starter switch has the start position in it.
If the starter switch that you have is the Case OEM then you need the button connected into the circuit.

There actually is no starter switch or button. I found some generic start buttons online for $15. It looks like the key/ignition switch is more like $100...so I was just going to put in the start button for now. Then add the ignition switch later on when I've re connected more sensors.

...or I guess I can try and find a generic 3 position ignition switch

 

[Tinkerer]

Get a good quality switch from NAPA or a similar source.
Unfortunately I bought a cheap Chinese one on eBay.
It stuck in the start position and the starter was destroyed.

 

[melben]

I worked many years on those machines and my advice is to use a Bosch Style relay at the starter. From new even the standard wiring was marginal and not heavy enough to reliably start with the Nippon starter which take a lot of solenoid current. Those relays are cheap and NAPA has a matching socket with leads. With that relay setup #18 wire from the dash is plenty sufficient and it is easy to wire up

 

[frankdb]

I worked many years on those machines and my advice is to use a Bosch Style relay at the starter. From new even the standard wiring was marginal and not heavy enough to reliably start with the Nippon starter which take a lot of solenoid current. Those relays are cheap and NAPA has a matching socket with leads. With that relay setup #18 wire from the dash is plenty sufficient and it is easy to wire up

Thanks. I'll look into this. Are those Bosch relays pretty weather resistant?

 

[melben]

Yes, they can even be bought with a sealed socket but you may have to shop online for that, if you go that route use a bit of dielectric grease on the socket and relay blades. another thing I have been doing is tying one side of the relay coil onto the hot 12v wire, that way you only need a simple ground at the dash switch.

 

[frankdb]

Yes, they can even be bought with a sealed socket but you may have to shop online for that, if you go that route use a bit of dielectric grease on the socket and relay blades. another thing I have been doing is tying one side of the relay coil onto the hot 12v wire, that way you only need a simple ground at the dash switch.

Thanks again! Using your method do you think I can eliminate the 40amp auto reset fuse? I'm thinking I can use the spot where the fuse is to mount the relay instead.im just thinking that since there is going to be a much shorter high current circuit I might not need it?

 

[melben]

I have done many on backhoes and skid steers and have never had need for a sealed socket, these setups can be hooked up and zip stripped to anything , mounting them has never been an issue