I have a 55 TBird that I recently converted to 12 volts and replaced the generator with an alternator. I followed the instructions that have been well posted by many and the conversion went very well.
I had read several articles about making this conversion and they all seem to follow the same set of instructions. But as a precaution I had a very strange and unlikely problem occur that could also have been dangerous.
In many of the instructions I read indicated that it is ok not to change the starter. I did not change my starter leaving the six-volt unit in the car. It has now been six months since the conversion and I have been driving the car without related issues to the conversion until the other day. I needed some repair work done on the power steering so I took it to my mechanic. After I gave him the keys he started the car and the starter never disengaged. Further, he turned the key off and the car continued to run with the starter engaged. I’m fortunate to have a battery quick disconnect and I was able to stop the engine. But as soon as I reconnected the battery the car started up with the key in the OFF position and the starter remained engaged. Once again the only way to stop it was to disconnect the battery. Needless to say there is only one component that can cause this symptom, the starter solenoid. With one more connection of the battery I was able to stop the engine by smacking the solenoid. Because of the conversion I of course changed the starter solenoid to a 12 volt unit and I installed a MotorCraft 11450-A which is the unit called for on a 1956 TBird.
There are two possible causes of this problem:
1) The solenoid became defective on its own in just six months (I kind of doubt it)
2) The six-volt starter requires more current than the 12-volt starter – even though 12 volts is being applied to it. It is designed to pull more current. By not changing the starter and leaving the six-volt unit in the car could have placed excessive current demands on the 12-volt solenoid contacts causing them to stick closed. (As a note I had spent several years in field service on mainframe printers and copiers and I had several instances whereby relays would fail in the closed position due to excessive current draw “welding” the contacts physically closed.)
The starter circuit is generally very reliable and safe. However, in my opinion leaving the six-volt starter on a 12-volt conversion could be related to this problem.
Best regards
I had read several articles about making this conversion and they all seem to follow the same set of instructions. But as a precaution I had a very strange and unlikely problem occur that could also have been dangerous.
In many of the instructions I read indicated that it is ok not to change the starter. I did not change my starter leaving the six-volt unit in the car. It has now been six months since the conversion and I have been driving the car without related issues to the conversion until the other day. I needed some repair work done on the power steering so I took it to my mechanic. After I gave him the keys he started the car and the starter never disengaged. Further, he turned the key off and the car continued to run with the starter engaged. I’m fortunate to have a battery quick disconnect and I was able to stop the engine. But as soon as I reconnected the battery the car started up with the key in the OFF position and the starter remained engaged. Once again the only way to stop it was to disconnect the battery. Needless to say there is only one component that can cause this symptom, the starter solenoid. With one more connection of the battery I was able to stop the engine by smacking the solenoid. Because of the conversion I of course changed the starter solenoid to a 12 volt unit and I installed a MotorCraft 11450-A which is the unit called for on a 1956 TBird.
There are two possible causes of this problem:
1) The solenoid became defective on its own in just six months (I kind of doubt it)
2) The six-volt starter requires more current than the 12-volt starter – even though 12 volts is being applied to it. It is designed to pull more current. By not changing the starter and leaving the six-volt unit in the car could have placed excessive current demands on the 12-volt solenoid contacts causing them to stick closed. (As a note I had spent several years in field service on mainframe printers and copiers and I had several instances whereby relays would fail in the closed position due to excessive current draw “welding” the contacts physically closed.)
The starter circuit is generally very reliable and safe. However, in my opinion leaving the six-volt starter on a 12-volt conversion could be related to this problem.
Best regards
