MTFCA Forum

I have a Model T with a 12 volt system, with a 6 volt starter. I have had an issue with the starter spinning to fast, so I have been able to hand start the car for a few years, no problem. The issue now, I would like to use the starter, on cold days.
The starter hardly turns the motor over, besides start it. The battery shows to be changed but under load, the starter fails.
I put jumper cables from my modern car to the battery and the same results.
Could the starter be burnt out from the 12 volt system, what else can I try.

George

Hi George,
The two years may be the issue. Pull the band off and look at the comuntater & brushes. They may be corroded or oily. If its oily and you sray it out with contact cleaner or brake clean blow it out or let it dry before trying to start it most cleaners are flamable. If they look good try jumping to the starter terminal and grownding to one of the mounting bolts on the starter. If it cranks then you have a connection or switch issue. The Model T starter is one of the best ever made its the drive that is the weak spot.

Good answer. Also check if the starter stud is loose. That soldered connection is a common weakness. Many folks run a 6v starter on 12v. That usually tears up the bendix drive. Doesnt sound like your current issue unless it has jammed up. With the brush cover removed you can insure that the armature it still rotating freely.

I did something similar to you....at first. After some bendix trouble and the fact that the starter wouldn't always turn the engine over when hot without hand cranking it beyond compression, I installed a modern, 12 volt geared starter. It works good, with none of the problems people deal with using original starters. See my post <https://mtfca.com/phpBB3/viewtopic.php?f=2&t=20676> To me, reliability is more important than having everything original. I hate breaking down on tour

Using a 6 Volt battery, a standard stock Model T engine will turn over and start with as many as 3.2 to 3.5 Volts being measured at the starter terminal and a good engine ground.

Using a 12 volt battery, with the same configuration will normally measure only 8 or 9 Volts there.

If your engine has good compression (50 to 56 psi), good coils and a good carburetor, it will start right away and before the starter is damaged.

I get a lot more free starts since I put a Russ Potter rebuilt carburetor on my stock engine.

I only have to open the hood and turn the crank over until the pulley pin is straight up, then turn the crank about 48 degrees more (best guess) and turn the key to Bat.

The engine is running and saving a lot of battery energy and starter wear.

Hello. UNPUR....IF someone in the past changed out the battery cables to go with a 12 volt battery they will be a lot thinner than these 6 volt original cables.... 6 volt cables are usually 00 gauge, and will convey better amperage power from the battery to the starter.

Unprr...... Sorry for misspelling.. let us know how you make out.

If you have not used the starter much over the years, preferring to hand crank, the trouble may be the rear whitemetal bush in the starter. I have just rebuilt a starter for a mate with a 1913 roadster. The starter was getting slower and slower, until finally it quit.The potmetal bush was frozen on the armature shaft and was attempting to spin in the end cover on the starter.

Allan from down under.

When I bought my T back in 2001, the buyer, who had bought my T in1996 and passed away from cancer in 2000, had installed a 12v system. When I got it home, I immediately converted it back to a 6V system. When I rebuilt the engine in 2010, the bendix spring had been slammed so hard by the 12v system, it was deformed so that the bolts were on opposite sides of the starter shaft and he brass ring gear had to be replaced.

The bendix spring is designed to return the bendix gear back to its’ proper starting point. The first picture is what an undamaged spring looks like with the bolts on the same side. The second 2 pictures are of the damaged spring that I found in my engine that had been deformed by high pressure caused by a 6V starter being connected to a 12v system and subjected to higher torque than it was designed to take. This kind of torque can also damage the teeth of your brass ring gear. Jim Patrick

Jim, I agree with your post but just what and where is the “brass ring gear”?

The ring gear, #3268 in the diagram, is mounted on the heavy flywheel on the side opposite the magnets. The bendix gear engages in the teeth of the ring gear and is what turns over the engine to start the car. Jim Patrick

George, have you opened and cleaned the contact plates in your starter switch? That is another location for electrical resistance.

Ring gear is steel, but the bolts are brass. However, even the steel parts are not immune to injury caused by 12V as noted above.

Unprr wrote: ↑

Sun May 02, 2021 3:36 pm

"...........what else can I try."

George

Shotgunning an electrical problem can be time consuming and frustrating. Here are a couple of quickie tests to help you eliminate or discover a lot of problems with very little effort:

1. Depress the starter button for around 3 seconds. As soon as let off the button, gingerly feel each connection or terminal to see if it's really warm or even hot. Be careful; you could burn yourself when you hit paydirt. A hot wire or hot connection indicates excess resistance.

2. If you don't find any hot spots, you may well have a bad battery or the hot spot is deep inside the starter where you can't feel it. At least now you know your switch and the connections that you checked are OK.

3. Next, check the battery. Connect a voltmeter (set to DC volts) to the positive and negative battery posts (not the battery clamps, but directly onto the posts). Look at the meter to see what it's reading. Now depress the starter again for a couple seconds and watch the voltmeter. Did it go way, way down ? After you let up on the starter button did the voltage jump right back up near 12, or did it slowly recover to something less than 12 ? If the voltage jumps right back up near 12, the battery is probably OK. But if the volts dropped way down and slowly recovered back to something less than 12, you probably have a bad battery or it needs to be charged.

If the battery checked OK and none of your connections were warm (or hot), you'll probably need to move on to the starter. But at this point you have eliminated dozens of possibilities in just a few minutes.

Dick

I never knew the flywheel ring gears available today, were steel. I purchased two ring gears in 1971 (one as a spare) and could swear that they were both solid brass, because I recall thinking how nice they looked and wished there was some way to show them off inside the transmission. Am I imagining this? Does anyone else remember when the ring gears were brass? When did they change to steel? Isn’t this a detrimental change? I assumed they were brass because if one or more of the brass gear teeth were sheared off inside the transmission, they will do a lot less damage than broken steel teeth. Jim Patrick

Never seen a brass ring gear. Been in this hobby since the 70's.

Yeah, ring gears were never brass...so many possibilities why the battery won’t turn over the engine... here’s another: while on a recent club tour I starter motor my T over and over until I couldn’t any more. Had coils, lights and horn but nothing when I pressed the starter plunger. Found out the positive cable was just not tight enough on the battery terminal. 1/2” open end wrench fixed the problem.

Hi George,
I don't explain this very well so go to youtube search voltage drop test no crank slow crank. There should be enough info there to show how it is done. By doing a VOLTAGE DROP TEST you will find what & where your problem is. Look at several videos you will get the idea.
Craig.

Thanks Craig but I just did a cursory eyeball check for half a minute; found and fixed the loose battery cable.

At 6 volts You can't afford to lose any power in bad connections. Otrcan / Dicks quickie test is right on the money.
Glad You found the problem. "It's the little bugs that eat Your lunch"

The negative battery ground is connected to the chassis by means of a short cable. I have never seen it personally, but I have read posts on the forum whereby there have been occasions when the starter and other engine mounted accessories had a hard time obtaining a good ground due to excessive paint that prevented the ground from getting from the chassis to the engine. To remedy this, some have run a cable from the engine to the chassis to create a direct negative ground connection between the chassis and the engine. Jim Patrick

UNPRR,

Did you receive my reply to your Private Message a few days ago ? If not, could you please email me at dick(dot)fischer(at)mac(dot)com.

Dick