I am new to this forum and have a question for you guys. When I built my 1926 Model T in 1962 my friend and well known Model T guru, Chris Egsgaard, instructed me to connect the positive battery pole to the frame and the negative pole to the start button. I have had it like that ever since but the car has always cranked slowly. The question is will reversing the polarity help the starter motor crank better and if I reverse the polarity do I have to be concerned with anything else except probably reversing the wires on the amp meter? Could Chris have been trying to limit fire potential which I am told can rarely happen while a Model T is at rest?
Model Ts came from the factory as 6 volts, negative ground. Why Chris told you to wire yours as positive ground, I don't know. Does your T have a non-stock ignition system or other accessories that would require positive ground?
Your best bet for improving starter performance would be to clean and wire brush every connection (including the ground side) to minimize any voltage drops.
Regarding the fire risk,Model Ts didn't come with any fuses, but you can add one per the drawing in this thread:
ALL Model T's are negative ground ALL Model A and Ford cars up to about 1954 are positive ground. It will not hurt to have the car positive ground. If you use a modern type cutout you will need the correct one for positive ground. If your starter is slow could be several things, grounds need cleaning, starter needs attention, battery is weak, tight engine, wrong battery cables used (should be 0 or 00). There would be no difference in fire potential irregardless of what ground you use.
Henry -- Welcome to the Model T community. All Model T's were negative ground. Model A's were positive ground, so sometimes folks think T's were as well. I don't know the answer to your question about slow cranking with the polarity reversed. Chances are that you have either too-small cables or a bad ground where the cable attaches to the frame. Cables should be 0 gauge ("one-aught") or 00 ("two-aught") size. Smaller cables will cause slow cranking. To correct the bad ground, remove the cable from the frame (you'll be doing that anyway when correcting the polarity) and sand the end of the cable and the frame where the two meet. Shiny bare metal is what you're looking for.
I guess I'm a slow typist. There were no replies when I started.
Model Ts are not firebugs. If your wiring and switches are up to snuff (which they should be) not a single fuse is needed. Everything works perfectly as designed.
That's ok Mark S posted 2 times and found a link while I was typing and correcting my spelling! LOL
and yes, welcome to the forum.
Thanks for all your comments. I feel better about reversing the polarity now. I was not certain if that could cause a problem so turning to all of you for some expert advise really helps. I'll clean up all the contacts and probably replace the cables and hopefully it will accomplish better cranking.
The whole positive/negative/positive/negative ground thing basically dates back to the '60s and '70s when "FORD" mechanics forgot that model Ts had been negative ground and started telling everyone that ALL antique Fords including model Ts were supposed to be "positive" ground. Once that sort of misinformation gets out there, it can be tough to reel back in.
But, the fact is, that model Ts are, were, and always were, originally negative ground. However, the simple systems really doesn't matter, much.
It CAN matter, a lot, if your car has some kind of a voltage regulator, or a diode instead of a simple cutout (relay type things). If you change the polarity? You likely will NEED to "flash" the cutout and/or generator (with engine not running, short around the cutout between the battery and generator for just a fraction of a second). You may also have to reverse the wires on the ammeter. Nothing quite like a simple screw-up on a simple system to really complicate things.
Polarity generally will not have much effect on the speed or power of the starter (although I have seen it happen, corrosion CAN have a diode like effect that is polarity sensitive). As previously said, starter power and speed problems are most likely related to poor connections or starter cable sizes and lengths.
Thanks Wayne... I think I'll leave the polarity alone and replace the cables and clean up all connections on the frame, switch and starter motor. Hopefully she'll crank better then.
While the T starter is not supper fast to start with, in most cases the engine does not need to be spun supper fast. Try hand cranking (with the switch off till you get use to the car and know it's ins and outs), that is about all the speed most need.
I can't believe Chris would have told you to do that! I knew Chris from the time I was 17, and can't believe he would say that!
Speaking on behalf of electrical engineering I would say that if "everything works perfectly as designed" then nothing needs a fuse. The problem is that many of the parts are not made "as designed" so I strongly suggest one fuse placed at the source of all T wiring system power namely the heavy yellow wire connected to the battery side of the starter foot switch. Put a 25 amp fuse in a SEALED fuse holder there and you don't have to worry about anything.
FYI The last 6V and last positive ground Ford car was used in 1955. I had a 1955 Ford Sunliner Convertible in high school. For 1956 Ford went to 12V negative ground and it stayed there. My '55 had a '56 312 Cu In V8 in it and that 6V system turned it over just fine even though it also had high compression pistons in it. Cable size is everything and of course the most common mistake is that folks even behind the counter at the parts store are often not aware that you need heavier cables for 6V systems than 12V. People put on "all new" cables but they are 12V and thus a step backwards since they are lighter by a long shot.
As for wiring diagrams - almost all of them listed as 1919-1925 are in error in that they show a battery horn wired to a horn button with the power coming off of terminal #1 (leftmost on the terminal block). The reason that is wrong is that while the car had a starter and generator since 1919 - the BATTERY HORN does not show up on any T until March of 1922. Before that early starter cars (1919-1922) had magneto horns as did the 1918 cars.
Chris was a great guy an enormous help to me by providing parts and expertise in 1962. I knew very little about the Model T and relied on Chris. I distinctly remember him telling me to use the positive post to ground. I never knew exactly why but who wore question Chris. Its worked well for the 55 years since I built the car and only now questioned it. He must have had a reason.
John F. When did a horn become required by law? What years were they only accessories? The parts books are somewhat unclear about horns. Some list horns but no applicable years and some do not list any horns, however they appear in the accessory parts books, but again, no applicable years. There was a picture on the forum with 1914 models on the assembly line all with bulb horns. Some 15s had bulb horns, mag horns, hand operated klaxon and with no horns. I have a 15 (Canadian early model) with the forked head lights and it has the horn wire tube under the steering column with no horn nor any evidence of a horn. There was no hole in the firewall to mount a mag horn.
I believe all mechanical horns were aftermarket accessories, popular because they're louder than a bulb horn or a mag horn.
Henry, Cleaning up all the starter's connections is a good start, but I would guess you'll wind up pulling the starter apart any ways. Most of the vintage Model T starters I've seen have been full of oil residue. Ford's solution to engine oil bypassing the bearing was to put a hole in the front of the starter case to drain it out. That probably worked for a while before it too became plugged up, then the rest of the starter eventually got a nice bath in dirty engine oil. The resulting gunk does a magnificent job of raising resistance on the brushes and commutator. If you have it apart, a good idea is to take the armature to a reputable automotive electrical shop and have it tested on a growler before throwing a lot of resources into it.
Thanks for the heads up on the starter Kevin
If you hook up the ground backwards, does the engine run backwards?
Add a few drops of MMO to the battery and you won't have any problems with polarity...
Model T's are negative ground from the factory. My Father bought a New NAA Ford Tractor in 1954 that came with positive ground. I still use it and have always wondered why it has a positive ground.
When I was growing up and working around other tractors and cars I always had to remember that the NAA was positive ground and everything else we had wasen't!
MMO, Battery Polarity backwards, and a water pump....sounds like a Chevrolet
I don't know the answer to the law with regard to horns since during the T era the various states all had their own laws regarding the newly emerging vehicles. I do know that I was going to research the electric lights at one point and realized it to be a huge undertaking since every state seemed to have a different law with regard to light brightness for headlights. The light bulb suffix that often was changed for each vendor got a real workout since the suffix got as high as the letter "H" as I recall and that in itself was not the end since a number then followed the letter like H1 or H2... for the various manufacturers of a particular bulb. What Ford supplied as horns really is fairly well documented with regard to design change but you have to use your own judgement as to how much time delay a change may have taken to then be found on a production car. Generally 14 used a bulb horn. 15 used both bulb horn and mag horn mixed. 16-early 22 used mag horn but there were different styles in the early 15-17 era and many if not most of those had 2 wiring connections. The combo light switch and horn button device used single horn wire connection to the mag horn while the simple 15/16 horn button used the 2 wire connected mag horn and most of those had short horn bell on them with 1915 versions having brass bell but not shiny brass but just painted. I have not seen any shiny brass horns that I think were in fact manufactured that way as mag horns but maybe there were some.
I think lots of states had no laws on lights and horns while others had strict detailed ones but I have not gone beyond just noticing that in the archives. I am not interested in what the lawyers were doing to start their usual "CONTROL" of things that they need so desperately to do so that the world will be safe. Research T headlight bulbs if you want to see legality run a muck
If you pull the starter; the bendix HAS to come off first. I HIGHLY suggest if you are going to do any work on your Ford getting a copy of this;
All the T parts dealers carry them and can be found used on several sites. Just google the title.