I am starting to rebuild my transmission and have some questions. How do I check the magnets to see how strong the pull is? How do I recharge the magnets if they are too weak and how do I know if they are too weak? I am using the green book for instructions (The green reprint put out by Ford), is there any better books out there?
That is all for now, more questions later.
A basic test for a magnet is that it should be able to lift a cast iron piston.
The Ford Service Manual is great, especially if you have a large stock of NOS Ford parts like every dealer had when the book was new
MTFCA sells a good transmission manual that is written for the hobby restorer:
The MTFCA electrical manual will tell you how to rewind the coils too.
I've read all three - plus Murray Fahnestock's old writings and the forum. Fahnestock tells about the importance of getting everything straight from the crank to the driving plate - and here's a new free service that tells you a lot about assembling a T transmission properly - the Model T Tips Youtube series:
Every Model T owner should have a complete set of the repair manuals from the MTFCA. They are loaded with great info and help with trouble shooting problems when they crop up.
While the traditional magnet test is holding a cast iron piston, about two pounds, but you can double that. The last time I charged magnets I got them all to hold four pounds easily, and some held almost 4½ pounds.
There are as many ways to recharge magnets as there are days in a month and available equipment. With some instructions from my electrical guru friend I devised this electro magnet recharging coil and there are probably a dozen different design methods. The steel/iron magnets used on Fords will only attain a maximum flux that is magnetic flow. It is like relating it to an 8 ounce glass containing water that is half full and refilling it with a 5 gallon pail, it will only hold so much. When making a magnet recharger the size of wire and the number of turns are issues of special attention. The area of the recharging device must at least equal the area of the magnet being charged to assure maximum flux flow. There are several testing methods after the fact, there are hand cranked testers, meters, light bulbs, but the main test is will it start and run on the magneto? You will have to be the judge of the best advice. My recommendation would be replace the magnets with professionally charged new ones.
Thank you everybody. Craig
the iron slug shown in the ford literature above is approximately 1.92 pounds, fwiw. jb
That 2 pound weight is the minimum value that the Magneto will work with, if the spacing is only between .025 and .030 all around.
A good set of charged magnets will easily hold a 5 or 6 pound weight or more than that, which is primarily dependent on the weight smoothness surface and magnet pole contacts with the weight.
A simple "poor man's or shade tree mechanic's) way to insure that spacing is correct is to stand the engine on its nose with the flywheel attached.
Then pick a Coil Ring Coil and turn the flywheel all the way around, measuring the gap for each magnet pole.
Then select a flywheel magnet and turn the flywheel all the way around, while measuring the gap between that magnet and each Coil Ring pole.
Then you will know for sure that all the magnets are the same height and the coil ring is properly shimmed for good operation.
It is best to make a chart and write down each space value for both tests.
You can also buy a tool to do the same thing for about $200.