12 volt starter

[Bob Prochko]

I recently purchased a little ‘26 coupé. Nice car, but the previous owner made certain “updates”.

Most notably he changed the electrical system over to 12 volt. Now, since this car has no magneto, the coils work splendidly on 12 volts, but I really worry about the way that the Bendix crashes into the ring gear when I press the starter button.

I see that Snyder’s is offering a gear reduction starter motor for this application, but of course it is expensive.

Would the use of a series resistance, like a spare Bendix spring, really help? I’m running the car in daily service for the time being while I rebuild the carb on my Chrysler, and don’t want to cause any problems.

I know that the correct solution to the problem is to rebuild the engine/transmission assembly completely, and get everything running exactly the way it was designed, but I’d like if possible to get a couple more years out of what I’ve got.

Also, I’m looking for a rebuildable core engine/transmission. Serial Number around 12,000,000 preferably, but in reality any ‘26/7 unit would work. Heck, the best engine I ever had came from Donald Lang. It had a serial number which would date it to 1938.

[Norman Kling]

Unfortunately, the addition of the bendix spring in line will not affect how hard the bendix hits the flywheel. You can rewind the starter to use 12 volts. I am not sure how it is done, but Ron Patterson should be able to help you, or others in the club who are more knowledgeable.
Or an easier less expensive way would be to use a 6 volt battery for the starter and change your ignition coil to a 6 volt coil. Most of the earlier distributors used during the 1930's and 1940's used 6 volt systems, so you should be able to find a coil that would work. These would be GM or other makes. Ford V8 coils would not work. Don't know what you are using for a generator, but a standard T generator would charge a 6 volt battery.
Norm

[Oldav8tor]

This subject has been discussed a lot. You might search the forum using keywords like "Starter" "Bendix" "12 volts" etc. For my first year I ran a six volt starter on 12 volts. I put the battery under my backseat (Touring car) ran #4 wire to the starter with an old bendix spring inline to get a bit of a voltage drop. It worked OK and the spring did seem to reduce the slamming somewhat based upon my observations. The recurring problems that plague the bendix along with the fact that the starter sometimes struggled to turn over the engine when hot (high compression head) caused me to buy a 12 volt WOSP geared starter. I have been very happy with the new starter. I sold the six volt starter and a spare bendix that I carried and recovered most of the cost of the new starter.

I consider a reliable starter to be a safety item. My '17 never had a starter so I've already offended the purists. It works great for me and nothing that has been done can't be undone.

[Bob Prochko]

I’m using four Model T coils and a timer. They are barely adequate on a six volt battery but work splendidly on 12 VDC.

[kelly mt]

Bob, I have four T's two of then 6v and two 12v. I've not had a bendix problem. One 12v car has an actual 12v starter. I just haven't had an issue but in all my cars I carry a complete spare bendix with a key and new bolts. You never know with ancient machinery.

[jsaylor]

I have broken and deformed many Model T Bendix springs using 12 volts over the years and have been using a Model A Bendix spring which is much heavier. It does fit. I am also using a LD Becker 12 volt starter but sadly these are no longer available since Larry's passing. The T starter can be rewired to 12 volts by changing the field coils from a parallel configuration to series.

[DickC]

I'm no expert but I too have a coupe with 12v alternater and a 6v starter. I think the biggest problem is making sure that you have fully retarded the timer prior to starting. I may have problems in the future but don't right now.

[TRDxB2]

As stated its been discussed many time. The simple solution is to use a dropping resistor. Many owners have used an old Bendix spring to drop the voltage. There are also electronic choices available - no one ever recommended one. Hopefully someone will weigh-in on using the one (or similar) that Speedway sells for $19.94 https://www.speedwaymotors.com/Electric ... 15824.html

[speedytinc]

Another option is a clip on 6V distributor. There is that cost plus getting rid of your alternator.(assumption) & un-convertingthe lights. About the same as a new 12v starter.
If you stay with the current 6v starter on 12v, carry all the bendix related parts, gasket, tools, puller? Play the wheel. Or plan on hand cranking when it fails. What does your ring gear look like & whats it going to look like after continued abuse? Bendix failures are easy to fix, not so much the ring gear.
You are smart to recognize a need to deal with this.

[speedytinc]

As stated its been discussed many time. The simple solution is to use a dropping resistor. Many owners have used an old Bendix spring to drop the voltage. There are also electronic choices available - no one ever recommended one. Hopefully someone will weigh-in on using the one (or similar) that Speedway sells for $19.94 https://www.speedwaymotors.com/Electric ... 15824.html

Thats only rated @ 10 amps. "For heater motors" Great idea If a Bigger one exists.

[TXGOAT2]

The Bendix spring placed inline with the starter cable is a dropping resistor. (It will get hot when in use) Trouble is, as someone pointed out, its resistance is fairly low when cold, so the starter will still slam the Bendix. As the high cranking current quickly heats the steel spring, its resistance will rapidly increase which will protect the starter to some degree, but probably not the Bendix.

[speedytinc]

The Bendix spring placed inline with the starter cable is a dropping resistor. (It will get hot when in use) Trouble is, as someone pointed out, its resistance is fairly low when cold, so the starter will still slam the Bendix. As the high cranking current quickly heats the steel spring, its resistance will rapidly increase which will protect the starter to some degree, but probably not the Bendix.

Correct. a bendix spring resistor does the opposite thing you want or hope it to do. You get the slam, then the lower motor speed. I do like the idea of converting a stock starter field to 12v, as shown in previous posts. Someone should offer them for sale or offer a modified set of field coils.
This may be beyond a lot of T owners ability.

[paddy1998]

As stated its been discussed many time. The simple solution is to use a dropping resistor. Many owners have used an old Bendix spring to drop the voltage. There are also electronic choices available - no one ever recommended one. Hopefully someone will weigh-in on using the one (or similar) that Speedway sells for $19.94 https://www.speedwaymotors.com/Electric ... 15824.html

That's for a comparatively low amperage operation, like a blower motor or something. The amperage going to the starter would smoke that - literally. And maybe your car too.

[Luke]

As has been correctly identified the use of resistance in the 12V supply to a 6V starter isn't really going to achieve a great deal.

However there is a reasonably inexpensive and simple method to modify the 6V Model T (and Model A) starters to 12V operation - by altering the field coil configuration.

In both cars the four starter field coils are wired in series-parallel (ie. two pairs of series-connected coils that are themselves wired in parallel). WIthout going into things in too much depth you could consider each field coil a '3V' coil, thus each pair wired in series makes a 6V system, and when paralleled they remain at 6V.

The application of 12V to these coils (and the armature windings) will result in a much stronger magnetic field and higher current draw than is required, which in turn will mean higher stress on the starter mechanism.

To alleviate this you can re-wire the field coils to be all in series - ie. 3V+3V+3V+3V = 12V. The job is a little fiddly but not especially difficult in my view.

Essentially you need to dismantle the starter, disconnect the field windings (and, as I recall, one of the brush wires) and reconnect them to be all in series. To do this you need a good-sized soldering iron and some heavy wire or copper strap to augment the existing wiring, and probably some suitable insulation material to ensure the re-wired connection don't short to the starter casing (or other wiring).

If anyone is interested in this I can draw it out and scan to put up here, but I'm fairly sure others will have already done so?

UPDATE:

Well, it didn't take long to find - I should have searched before typing all that out - see here from Jeff: viewtopic.php?f=2&t=10169 (where's the thumbs-up emoticon when you want it!).