Thought I had a starter issue with our '20 TT, so pulled it as per the old Ford manual, hooked the battery to it, (it read 6.2 V), and looped my meter over the cable. Instead of reading the 50-75A that the manual said I should see, I read .8-1.1A Obviously I'm missing something here- like a load- but the manual doesn't say anything about that, so I assumed free running, though the 50A figure for a free running motor seems absurd. Help please
Is your clamp meter rated for DC? Most clamp meters measure AC only. In addition, the meter will almost certainly pick up the large amount of noise that the starter makes.
My meter is not rated for DC, but I was told it didn't matter, that "amps are amps". So I'm assuming from you're reply that it does matter. If I can find someone with a meter that reads DC amps- am I still looking for 50-75 amps unloaded that the manual calls for?
Here's an older tread on this subject:
Pro starter rebuilder Ron Patterson wrote: "The starter free run spec is 70 amps and the stall torque is 11-12 foot pounds at 550 amps draw"
MTFCA sells a good repair manual covering all parts in the Model T electrical system for just $12:
Is this Hugh's brother?
Yes, a DC ammeter is required. The 70A spec is for the original starter with a babbitt rear bearing. A modern rebuild with ball bearings should be around 50-55A and about 13ft/lbs. of torque. The free-running rpm will be higher too. The locked rotor current remains the same but don't dilly dally on that test. A cheap battery may explode at that draw.
About the 50 amp free running draw, you have to remember that at 6 volts that is only 300 watts. If you converted that same free running power requirement to 120V house voltage, it would be just 2.5 amps. It makes sense when you think about it. Power (watts) = Volts X Amps
found a meter today and retested- drawing 100-125 Amps. Before I buy a complete rebuild kit, is there a certain component that this excess draw would indicate?
Most likely the bearings and/or dirty commutator. Grab the shaft and turn it by hand. It should turn easily with only the drag of the brushes.
Unless you have the equipment required to properly rebuild a starter John, it will turn out to be wasted money. I'm not being a jerk here, just being realistic. Is the armature straight, are the bearings good, are the bearings aligned, is the brush plate and insulator good, is the neutral point set correctly ... that's the easy stuff an average guy can do. Properly cleaning up the commutator isn't something easily done without a cutter, nor is evaluating the torque without building a jig for it.
The generator and starter are two things better left to the experts and then they will outlast you. In the long run it will be cheaper to have them expertly repaired by the FEW that do it right than to have to fix it over and over.
Starters don't require a "neutral point" nor does one need a "cutter" as the starter armature is not undercut as is the generator armature.
Sometimes just a simple cleaning is in order to remedy a sluggish starter.
Yeah I was getting the two confused. Dumb old head anyways!
Disassemble, clean it up, make sure the commutator slots are still undercut after you sand it. Don't use emery paper. Lube it and reassemble. More likely your problem is the starter switch, not the starter. One possible problem, is sometimes the terminal is overtorqued and breaks the internal connection. Your symptoms do not indicate that's a problem. Starters are pretty rugged, unless you are a real klutz, you should be able to handle going thru it.
Starter armature segments do not need to be undercut - they spin only momentary (supposed to anyway, if your starter & engine are "up to snuff").
Starters have to spin a lot more on the cars that use 12 volts to "really spin them" instead of making the car start right in the first place. With a correctly running car, the starter should only have to turn the motor over one revolution, two tops to start the car. How much does it really run during it's lifetime that way?