After tear down, what's the best way to clean the magneto and not damage the insulating material. PK
Pat, when I first restored my 1926 Model T coupe in 1970, I was a poor 16 year old with little money, so, did not have the money, nor were there the resources we have these days to get rebuilt ones, so I cleaned and coated my magneto coil. Luckily, the coil was good and it lasted me 40 more years before I replaced it with a rebuilt mag coil from Total Recoil.
Before getting started, make sure your coil is good. If it is not good, you will need to get a rebuilt one from Wally at "Total Recoil".
I cleaned mine using mineral spirits in a big tub which covered the coil. You need to use a solvent that is mild enough to dissolve the oil, but will not attack the insulation covering the windings. That is why you should not use a hot solvent such as lacquer thinner, Xylene or MEK, which will dissolve the insulation covering the flat wire of the windings and destroy your coil by shorting out your windings. Be sure to put several 3/4" blocks in the tub to sit the coil on so the oil and sludge will sink to the bottom of the tub below the coil. Also, keep the tub covered so your mineral spirits will not evaporate.
The cloth covering of the coils is very delicate so you need to be very careful to gently agitate the mineral spirits without touching the cloth by stirring it with a paint stick inside the coils and outside the coils but take care not to touch the coils themselves. When the mineral spirits turns black, change it out with new mineral spirits and repeat the process. You need to let it soak for at least a day and overnight in each new batch of mineral spirits. You really can't soak it too much. I soaked mine for over a week and changed out the mineral spirits 6 times until the mineral spirits remained clear and all the oil was lifted out of the coils just through soaking and agitating the solution by gently stirring it.
After all of the oil was removed from the coil, I let the coil dry for another week. After the coil is bone dry, put several coats of Glyptal red insulation on the windings. Don't be impatient or in a hurry. It takes time and can't be hurried. You must be sure to get ALL of the oil out and this can only be done through soaking for a long time. Jim Patrick
Don't bother trying to save an old original magneto field coil. Original insulation is old, tired, and brittle, sugar coating it won't last. Replace it with a rebuilt one. It will come apart sooner or later and you will have to do a tear down to fix it. Do it right the first time.
If I had been told that back when I could not afford the expense of a rebuilt coil, it would not have been much help and would have been terribly frustrating and possibly brought my restoration to a screeching halt. I absolutely agree that a rebuilt coil is the best option, if they can afford it, but some folks just are not in a financial position to spend the nearly $300.00 (perhaps more now) it takes for a rebuilt coil, especially in these difficult economic times.
Contrary to popular belief, it is possible to salvage an original coil, IF it is operational to begin with. That is why I went into such detail to answer Pat's very specific inquiry as to how to do something, instead of, what he should do, which is how I was able to salvage my mag coil, when, as an 16 year old kid, I was too ignorant to know I was wasting my time, yet I got 40 more years of use out of a coil most folks these days would have judged to be a lost cause or a waste of time.
However, If, when tested, it is found to be not operational then I agree, a rebuilt, or good operational replacement coil must be obtained. Jim Patrick
Sounds like some assumptions are being made here. (1.Is the coil out of the car?
(2.Was it working when/if removed?
If 1&2 are true, then Jim's process can work. However, I fall into Jack's camp, because removing the coil means you are into a major tear down of the engine/transmission, which is not a trivial task often repeated in the life of your car, a rebuilt coil is not cheap but a wise decision IMHO.
When i/we rebuilt the not correct 15 i washed and washed mine in diesel fuel but it was far from perfect and the next T got a Wally coil!! Some of the best money i ever spent!! Bud.
If you get a rebuilt field coil directly from either Wally Szumowski or RV Anderson, the cost is more like $200, not $300.
Magneto coil rings fall in to category of almost have to or have to.
Wood wheels, radiators, and mag coil rings are Model T items that that fall into that category.
After around 90 years they need to be replaced if you really want to drive a T that's reliable.
I would think that taking a functioning coil to a motor rewinding shop and having it dipped and baked would be a good possibility
I have done what A. GB suggests. Before I took it to the rewinder's shop I spray cleaned it with lacquer thiners to get as much oil off as possible. It makes for a cleaner job. The varnish coat adds some insulation and helps to hold it all together too.
Hope this helps,
Allan from down under.
We have not heard if his magneto was working prior to the tear down.
Assuming it was: I like Jim Patrick's method, but after you've cleaned it you can test it by using a low voltage battery and a compass. Maybe you guys can explain this better, but in my case, I used a run down 6V battery from the T, which was registering 3.85V at the time.
I hooked it up using negative on one of the mounting holes of the field coil ring, the positive to the magneto pick up terminal...and checked the poles with the compass. It was North, South, North, South all the way around the coil ring, so I determined it was still working. It pulled the compass poles very strongly.
Long story shorter, I've rebuilt the motor, it starts and runs on Mags, and I have re-used what I know to be a good old coil that has never been rebuilt before. We didn't have that luxury in South Africa, in the 50's/60's when my Grand dad rebuilt the car.
Now if the magneto was not working or doesn't pass the test... Total Recall, or similar is a good solution.
By the way, I did the same test on my '27 barn find motor... it passed too. Luckily.
If your magneto was in working condition Jim's advice could work but think about you are trying to paint or varnish the oily magneto and on oil no glue, paint or anything else will stay. Sooner or later it will come off and your coil ring will stop working.
If you are a low budget Model T'er why don't you do the magneto rebuild your self, it will be about $20.00 on material to do it. It will just take some time but I could do it so every body can do it.
A few weeks ago I posted on the forum how I did it but I can't find the subject, maybe someone smarter as I can find it.
Here is Andre's post about his magneto coil ring rebuild: http://www.mtfca.com/discus/messages/411944/436811.html?1397161056
Among other good handbooks the club has one covering all the electrical stuff in the T. It has a description on how to rewind the coils: http://modeltstore.myshopify.com/products/service-manuals
Thanks for that info Jim, I am going to try it on my low budget TT. Just for fun, it has never had a working mag as long as I have had it. So for me it well be fun to try it.
Great Tom. Good luck. Just be sure you test your mag coil on your bench using the method in the Model T Service manual and that it tests good before you start or it will be a waste of time. Jim Patrick