I couldn't find any information online on my particular problem, and I hope someone else can benefit from my experience as I stumbled through this. This should work on any tractor with, instead of a starter relay, a manually operated rod that moves a switch on the starter.
I have a John Deere 40C that I converted to 12 volt. It started and ran fine for about a year; then, suddenly, it wouldn't crank. I love the factory starter circuit: there is no relay, no solenoid, just a knob on the dash; you pull it and a long rod (the "starter operating rod", per the manual) moves a switch screwed to the starter itself:
Inside the switch, a little copper wedge completes a circuit between two copper pads:
I found that the switch was bad; the copper pad was worn away. I suppose there must be an arc every time you start it, and eventually, like any switch, the switch will wear out. I bought another at Tractor Supply for about $12.
Maybe 8 months later, the switch wore out again. "Well", I thought, "I guess I'll just buy a new $12 switch every year."
The next time the 40C wouldn't crank, though, the switch was fine: the copper pad on the starter itself was worn down. A friend suggested that my battery "was too big", as in too many amps, but I don't think that makes any sense. I couldn't figure out how to replace the pad, so I bought a used starter, another Delco 1107127, on ebay for about $100.
After another switch replacement, the pad on the second starter wore down too. Now I had two bad starters and a pile of bad switches. I considered buying a crank handle so I could start the 40C manually, but I think it would interfere with the blade, so I had no choice but to replace one of the pads.
I'm sure I have some of the terminology wrong. What I call the "pad" is the rectangular head of a 3/8 copper bolt; the head takes a 5/8 inch wrench, and a slot is cut into the end of the bolt. A copper nut inside the body of the starter secures it, then copper strips from the field coils are soldered into the slot. Where the bolt passes through the body of the starter, it runs through some insulating washers:
Plenty of tractor places sell a "starter repair stud", but they only work on starters with external threads. I couldn't find a direct 3/8 replacement for mine anywhere online, but several places sell a 5/16 bolt (as a "starter stud"). I considered using, but I didn't want to improvise a thicker insulator. Instead, I decided to scrap the original switch setup, and use a stud that would allow me to use a relay. I know it's not as elegant as the original setup, but now the only part that will wear out is a $20 relay with a lifetime warranty, and I'll (let us hope) never have to open the starter again. I replaced the original stud with this:
It cost about $16 on ebay and is sold as a "Delco Starter Stud Kit". Insulators and washers are included. Another forum suggested using a "soldering copper" to solder the copper strips to the stud, since a standard soldering gun won't get hot enough.
I bought a 2 pound soldering copper but I couldn't get it hot enough with a propane torch. It probably didn't help that I was working outside in 30 degree weather. Finally, I got frustrated, and instead of trying MAPP gas or something else, I just heated up the stud with the propane torch. Surprisingly, it seems to have worked, and I didn't hurt myself or break anything:
The relay fits many Ford trucks. Ask for a starter relay for a 1986 Ford F-150 with a 300. Conveniently, the bolt holes lined up with the original starter rod hole and another hole just above it, so I didn't have to drill.
I used a switch from my spares box, but almost any momentary switch should work. I knocked out a plug in the dash that is supposed to take an optional cigar lighter, and my switch happened to fit.
The wiring is just like any starter relay:
Of course, I had to remove the original starter cable that came straight from the battery, and replace it with 2 cables: one from the battery to the relay, and one from the relay to the starter. I used 4 gauge for both.
I previously installed a fusebox, and now it gets power from the large, always-hot terminal on the relay instead of cluttering up the positive battery terminals.
I've started it 6 or 7 times since, with no problems. We shall see how it works long term. I own a couple of Ford trucks with the same relay, and if it can handle two batteries on a Diesel V-8, I expect it to have no problem on the 40C. I still don't know why the original pads wore out; maybe both of my starters just happened to have pads that were nearing the ends of their lives.
Thanks for reading, and I hope this helps someone with the same problem. I welcome any comments on how I could have done it better.
I have a John Deere 40C that I converted to 12 volt. It started and ran fine for about a year; then, suddenly, it wouldn't crank. I love the factory starter circuit: there is no relay, no solenoid, just a knob on the dash; you pull it and a long rod (the "starter operating rod", per the manual) moves a switch screwed to the starter itself:
Inside the switch, a little copper wedge completes a circuit between two copper pads:
I found that the switch was bad; the copper pad was worn away. I suppose there must be an arc every time you start it, and eventually, like any switch, the switch will wear out. I bought another at Tractor Supply for about $12.
Maybe 8 months later, the switch wore out again. "Well", I thought, "I guess I'll just buy a new $12 switch every year."
The next time the 40C wouldn't crank, though, the switch was fine: the copper pad on the starter itself was worn down. A friend suggested that my battery "was too big", as in too many amps, but I don't think that makes any sense. I couldn't figure out how to replace the pad, so I bought a used starter, another Delco 1107127, on ebay for about $100.
After another switch replacement, the pad on the second starter wore down too. Now I had two bad starters and a pile of bad switches. I considered buying a crank handle so I could start the 40C manually, but I think it would interfere with the blade, so I had no choice but to replace one of the pads.
I'm sure I have some of the terminology wrong. What I call the "pad" is the rectangular head of a 3/8 copper bolt; the head takes a 5/8 inch wrench, and a slot is cut into the end of the bolt. A copper nut inside the body of the starter secures it, then copper strips from the field coils are soldered into the slot. Where the bolt passes through the body of the starter, it runs through some insulating washers:
Plenty of tractor places sell a "starter repair stud", but they only work on starters with external threads. I couldn't find a direct 3/8 replacement for mine anywhere online, but several places sell a 5/16 bolt (as a "starter stud"). I considered using, but I didn't want to improvise a thicker insulator. Instead, I decided to scrap the original switch setup, and use a stud that would allow me to use a relay. I know it's not as elegant as the original setup, but now the only part that will wear out is a $20 relay with a lifetime warranty, and I'll (let us hope) never have to open the starter again. I replaced the original stud with this:
It cost about $16 on ebay and is sold as a "Delco Starter Stud Kit". Insulators and washers are included. Another forum suggested using a "soldering copper" to solder the copper strips to the stud, since a standard soldering gun won't get hot enough.
I bought a 2 pound soldering copper but I couldn't get it hot enough with a propane torch. It probably didn't help that I was working outside in 30 degree weather. Finally, I got frustrated, and instead of trying MAPP gas or something else, I just heated up the stud with the propane torch. Surprisingly, it seems to have worked, and I didn't hurt myself or break anything:
The relay fits many Ford trucks. Ask for a starter relay for a 1986 Ford F-150 with a 300. Conveniently, the bolt holes lined up with the original starter rod hole and another hole just above it, so I didn't have to drill.
I used a switch from my spares box, but almost any momentary switch should work. I knocked out a plug in the dash that is supposed to take an optional cigar lighter, and my switch happened to fit.
The wiring is just like any starter relay:
Of course, I had to remove the original starter cable that came straight from the battery, and replace it with 2 cables: one from the battery to the relay, and one from the relay to the starter. I used 4 gauge for both.
I previously installed a fusebox, and now it gets power from the large, always-hot terminal on the relay instead of cluttering up the positive battery terminals.
I've started it 6 or 7 times since, with no problems. We shall see how it works long term. I own a couple of Ford trucks with the same relay, and if it can handle two batteries on a Diesel V-8, I expect it to have no problem on the 40C. I still don't know why the original pads wore out; maybe both of my starters just happened to have pads that were nearing the ends of their lives.
Thanks for reading, and I hope this helps someone with the same problem. I welcome any comments on how I could have done it better.