John Deere 550 alternator upgrade

[TOLEWIS]

I recently purchased a 550 dozer that needs some attention to the wiring. I'd like to upgrade to the one wire 10SI but not sure if i will need to modify the old pulley. I would appreciate any input on any issues other members have run into doing this.

[Jim B]

According to the parts catalog your 550 should have a Motorola alternator with an external regulator on it. As you are wanting to change to a Delco type one wire you may need to purchase a pulley. I don't remember if the Motorola pulley will work on the Delco type, or if it needs a spacer between the pulley and fan if it will fit the shaft. It has been a while since I have made that swap. You may just want to purchase a new pulley (diameter of about 2-5/8" is best to keep the alternator speed up) of the correct width for the belt. You only need to use the Battery wire from the original alternator. You can tape the ends of the other wires up and leave them without harm. If you have a charge indicator light it will likely not work with a one wire alternator, some 1 wire types do not even have the spade terminal and some that do, will not support the charging indicator light from them.