How to Convert a Massey Ferguson 35 From a Generator to an Alternator

Ryan Hotchkiss

Converting a Massey Ferguson 35 from a generator system to an alternator power converter improves the implement's electrical performance.

While the conversion reduces the authenticity of the antique MF 35, if you use the tractor for agricultural rather than collecting purposes, the conversion increases its value and the dependability. A generator does not charge a battery when at idle speed while an alternator can. In addition, alternators have the power to crank a battery when the weather is cold while a generator can falter. Of less importance but worthy of note, an alternator makes the lights on a tractor shine brighter.

  1. Determine if your tractor has a negative ground 12-volt system. Follow the cable attached to the negative terminal. If it is attached to the body or frame of the tractor or the engine block, it is a negative ground system. Place the positive probe of an ammeter on the positive terminal and the negative probe against the body of the tractor. If the ammeter displays 12 volts, plus or minus 1 1/2, it is a 12-volt system. If either of these are not the case, you must convert the tractor to a 12-volt, negative ground system before replacing the generator with an alternator.

  2. Detach the negative cable from the negative terminal, then the positive -- in that order -- with a crescent and socket wrenches. Unthread the nuts affixing the positive cables to the generator. It has two. One runs from the generator to the starter, the other runs from the generator to the regulator. Detach the sense line housing from the generator. Simply pull the housing from the alternator's casing. Unscrew the nut on the exciter field trap and remove the wire from the terminal. Remove the nut on the regulator that runs the positive cable to the coil.

  3. Grind the generator and regulator mounts off the frame of the tractor. Turn the grinder disk on edge in relation to the weld on each mount and grind through the welding beads. Weld the replacement alternator in the same locations from which you removed the used mount.

  4. Attach the alternator the mount with the nuts, washers and bolts provided by the manufacturer. Tighten the nuts on the bolts until the alternator is securely fastened. Attach one end of the new positive cable to the coil with the nuts provided.

  5. Attach the other end to the alternator's main power terminal. Plug the sense line housing into the alternator case. Attach the exciter field tap wire to the 1/4-inch terminal screw on the alternator with a washer and nut. Connect the battery's positive cable to the alternator with a washer and nut. Attach the other end to the positive terminal of the battery. Attach the negative cable on the tractor to the negative terminal.