I have a 12V battery which was in the '25 when I bought it, the starter is 6V and turns over very strong......what is the 12V doing to the armature and brushes on the starter? I have taken the starter out and cleaned the brushes and armature. Don't know how long the 12V system has been in but I have heard pro and con that it is okay to use 12V with the 6V starter. Any comments please.
The starter will hold up BUT the Bendix drive & spring won't !!!
After a while the Bendix spring will be toast.
After that the collar will break off the bendix gear.
And so on. .....
Steve struck the nail on the head. Here is a good method for over coming the cons, Take a #6 or #4 multi-strand wire (approx. 4 feet) and wrap it tight 12 times around a one inch outside diameter tube of some sort and then tap it with a rubber/plastic mallet to train it to stay. Leave enough bent up and straight to attach a lug for the starter & starter switch. You may use a hard density card board tube to assist after the forming. You now have a shunt to lower that voltage by about 2.5 volts. I have been running mine like this for about 20 years.
A cheaper way vs changing the field coils. Start engine at the 8 clicks down. Bam Baby!
why not rewire starter to 12 volts, the most i fear is not the bendix but the ring gear
Why not get a 6 volt battery. Many Model Ts worked for lots of years with 6 volts.
I like Henry's approach to the 12 vs 6V trama that's placed on the bendix. From experience, unless something is done, 12v will destroy the bendix spring. 20 years ago I put a bendix spring in series with the 12V lead going to the starter terminal to use it as a dropping resistor. (9.2V) It's still there and not a broken spring. I have it on 4 T's.
Drive over to your local TSC in Flagstaff and get a 6 volt Exide and put it in your Model T. Get some new battery cables also. Clean up the neg contact on the frame and you should be good.
My T came to me with 12 volt system and 6 volt starter. I drive it often and year round and never had a problem yet. Both starter and Bendix are holding up great.
Using a bendix spring or coil of wire will not reduce the voltage to the starter until AFTER the bendix has engaged the flywheel ring gear. The voltage drop at the starter terminal occurs when the starter motor feels the load of turning the engine.
I installed new positive cables from the battery to the switch and from the switch to the starter. Then I cleaned the grounding area and installed a new flat grounding strap. I've let my '27 T sit for 2 months and it still starts right up on my 6V battery. Why risk a Bendix? just all the connections up and keep the 6V battery charged. It won't give you any trouble.
Check out the following thread link to see what a 12v battery will do to a bendix starter spring. Jim Patrick
Some people still subscribe to the superstition that you need 12 volts. You don't.
My 1926 T has been 6Volts since new and will never go to 12v
When you have a good battery, correct leads (3) and a serviceable starter and push switch you donít need 12V
I have also added an additional earth strap from the starter retaining bolts directly to the chassis.
I do prime the carburettor then when you hit the starter switch you hardly hear the starter working before it fires!
I was told if you cut the cable going from the starter button to the starter and place a Bendix spring in between the splice, it will drop the current to about an 8 volt so it wouldn't be as hard on the starter AND Bendix spring when using a 12 volt battery. I took a Bendix spring, dipped it in liquid rubber and then used electrical tape over the whole spring for insulation. Has anyone else heard of this?????
Yes, I have seen a T Owner who had three Bendix Springs bolted together to make a in line resistor. There werenít wrapped up or insulated in anyway and worked well
We had a guy in our local club with one of those 12 volt bendix spring resistor arrangements on his 1921 pickup. Long story short, the starter bendix eventually broke and pieces of it got into the transmission and destroyed a few gear teeth. This necessitated the removal of the engine and rebuilding of the transmission as well as a new bendix drive. Needless to say, it was reconverted back to 6 volts.
I don't know about a T starter, but it was a lot worse than a bendix on my wife's Farmall H. Tractor had been "Upgraded" to 12v when we got it. It busted 2 end plates on the end of the starter before we fixed the problem. Had it been mine, it would have gone back to 6v, but she let someone talk her into shunting the starter and keeping the 12v. whatever. It's hers, not mine. Point is, slamming that bendix into the flywheel is NOT good for them. Maybe you get lucky and only damage a bendix. Maybe you do more damage than that.
I'll tell my story with 12volts. Originally dad had asked around to other T guys. 50% were for and 50 were nays. At 50% dad went for it, he wanted brighter lights for night driving encase he got caught after dark. After posting the question of safety to the forum in'98/'99most of the consensus was no good. Dad had 50% go for it and did. He didn't have any voltage reducer at the time. Worked well for a short time, but he ended up chewing off 4 parts of the old ring gear. So for about 5 years he did a lot of push starting. He didn't have a lot of upper body strength for hand cranking. He eventually had the engine rebuilt and the ring gear replaced with a new one. I'm thinking the old Ford gear was softer than the new ones. Once I had the car I experimented with it and removed the Bendix spring being used as a voltage dropper. Boy did that motor spin. Ended up breaking the Bendix Drive. Buddy had a spare and I was back in business with the bendix dropper back in place. Picked up a couple of spares from Eric Barrett at the Bakersfield Swap. One spare for me and one for my buddy. So that's my history with 12volts on a 6volt starter .
Your results may vary.
Rewired starters for 12volts are available if 12 volts are insisted.
I use a 6 ft skinny 12 volt cable to connect the 12 volt battery on both my T's and it works fine.
Royce Peterson's dad came up with the skinny 12 volt cable approach many years ago.
12 volts using heavy 6 volt cables slams the Model T Bendix and wrecks it in short order.
On my M Farmall I use heavy 6 volt cables and a 12 volt battery. No problem with this setup in the Farmall for the last 40 years.
My experience, your mileage might vary.
If your T will start with minimum starter assist, you may get by with it for a while, but it your T is temperamental in the cold, or the carb is not adjusted correctly, don't dare 'grind' or stay on the starter button too long. Don't ask why I give this advice.
If my Model T had already been equipped with a either a 6-volt starter or a 6-volt system, I'd have kept everything 6-volts. -No sense re-inventing the wheel, right? -But my car is a '15, which, of course, was manufactured with neither a starter nor any kind of electrical system, so when I decided I needed a starter (because of a spine injury), it made at least as much sense to go with a 12-volt system and 12-volt starter as 6-volt.-It worked out very well.
Terry, I am going to hazard a guess that your Bendix gear jammed into the ring gear and destroyed some gear teeth? In a hurry once and I used a 12V battery on my 6V starter. That's what happened to me.
I used to start my 1953 Chrysler Hemi with the six volt battery it came with so I can't understand why people seem to think they need 12 volts to start a low compression four cylinder engine. If the system is set up as designed and maintained properly it is more than adequate
The only truly safe and reliable way to get the job done is to convert the starter to 12 volts. You don't replace anything, you just rewire the field coils. You need a hot soldering iron and some knowledge of soldering though. I've done it on a couple of starters and it works fine. That being said, my car is 6 volts, and is going to stay that way. I wanted a little more "snort" when starting, so I purchased an Optima Red Top 6 volt battery. It has 20% more CCA than the standard 6 volt battery. Have friends who have 12 volts going to their 6 volt starters and mine turns darn near as fast. I can even start it on magneto with the starter if I want (or if I forget and turn the switch the wrong way).
It won't make it any better! Stick with six volts.
6 volts will work just fine but people have different reasons to go to 12 volts. It may be to run a GPS or use 12 volt LED tail lights and stop lights so that people don't run you over. Or maybe a stereo. Who knows.
If you want to use 12 volts and don't want to wreck the bendix, do as Kevin advises and re-wire the starter. The stock starter field coils are wired 2 in series and 2 in parallel. You want to change them to 4 in series. I did that to my starter and it works great on 12 volts. Have the current running the same direction in the field windings so you don't change the magnetic polarity. I posted some pictures a while back.
If an when using 12volts, does the spring break upon engagement or does it break after long cranking periods. Most of our cars, 6 or 12 volt start immediately when. I never have had a spring issue on 12 volt. Just curious if long engagements make for shorter life?
The spring bends, or breaks when the bendix gear slams into the stationary ring gear and then, suddenly stops and is distorted as at starter shaft continues to turning until the flywheel gets up to speed. Especially bad on a tight engine. Jim Patrick
Tom my car is going on five years of frequent driving on the same starter and bendix With 12 volts. I would not change a 6 volt car to 12, mine was 12 volt when I got it.
I cleaned up an old starter from my stash pile and was COMPLETELY AMAZED at how fast the 6 Volt battery flops the T over!
New concept to me. Electric starting. Cool.
You folks teach things that could/should wash over into other forums about 6 or 12 Volt starting! Are they listening?
Tired of hearing old engines turn over like they're sick.
Thank you everyone for all this information, I have the starter back in the '25 and have one pan bolt and a bendix cover screw to tighten and we will see how it goes. This is monsoon season in AZ and Flagstaff is getting hammered, I am soaked and will wait until tomorrow.