MTFCA Forum

Just when I thought I had everything mechanically done on my tt, the generator stopped making charge suddenly. I can’t pinpoint when it went out but I noticed it about 4 days ago. Since then I have only run the truck to try to determine what could be causing the issue. I pulled off the cutout and everything looked good. I sanded the points, still no charge. On top of that, my battery decided to off itself so I will be going to O’Reillys today to get a replacement. (Has a 1 year warranty) Before the battery went out, I tested the amp draw with the headlights on and the car off and it was negative ten amps. When I turn on the car, it’s about -10 amps. Before, the car would show 6 amps when it was on with no headlights. Do the generators just decide to stop working like that or is something else amiss here? Please help me out as I am no electrical genius.

Thanks, Jacob Mangold

Also I would like to add that I just put on new 6v 50-32 cp bulbs from langs. Not sure it that would have caused my issue but I did take them out an ran the truck, with no luck. No charge was being made.

You should use an analog volt meter directly on the generator output terminal.

The cutout is a wild card. If you have one of those cheap mechanical cutouts, its a matter of when it fails & kills your generator.

Lets go with easy first.
Pull the brush cover. Look @ the armature for oil build up.
Flush with brake or contact cleaner while running. Be cautious of a flash. (never happened to me, but others have that concern)
Check gen output. Do this after each thing done or wire the voltmeter for constant monitoring.
Next try cleaning the commutator with some fine Emory cloth or 400 wet/dry on needle nose or a long hemostat.
Next look @ brush height. Are the tension springs still putting tension on the brushes? Push on the brushes.
Lastly wiggle the 3rd brush a little.

If after all that, you still have no output, its rebuilt unit time.

Is your battery stone dead? It may have an open cell connector. If that's the case, the battery failure may have caused generator damage. The headlight bulbs will not cause damage.

I'd make sure the battery is actually dead, and not just discharged due to a generator, cutout, or wiring/cable/ground issue.

***** Also: Remove the generator and make sure that the drive gear on the generator shaft is in place and not spinning on the shaft due to a sheared pin. If it has come loose, it could cause serious damage. ****

Battery is in fact done for. I put it on my battery tender and it said bad battery twice. I will be pulling the generator hopefully tomorrow. I will post pictures of my findings.

Thanks, Jacob Mangold

Put the new battery in & try the in car diagnostics/minor repair.
You plan to pull the generator. Do you have the proper rebuilding equipment on hand?

I’m not sure exactly what tools I need. I do have a wide variety of obscure automotive tools. What exactly do I need?

Thanks in advance, Jacob Mangold

Jacob Mangold wrote: ↑

Tue Jul 25, 2023 6:29 pm

I’m not sure exactly what tools I need. I do have a wide variety of obscure automotive tools. What exactly do I need?

Thanks in advance, Jacob Mangold

If you rip it down for a complete overhaul you need a growler, hi voltage test leads,
commuter cutter & mica cutter, gear puller, new insulators need to be riveted back.

Look in the T1 service manual.

Wouldnt it be better to do the try the easy stuff first?

Yep, the easy stuff will definitely come first. I actually wouldn’t even bother with it if it was that bad. Langs sells refurbished ones for 195 which isn’t bad at all.

Thanks for letting me know, Jacob Mangold

Jacob,
If you run into trouble after you get it out, I'm happy to help walk you through troubleshooting. All I do is fix T starters and generators, and generators can be particularly frustrating.
. Jeff

Thank you Jeff. I haven’t had much time to look at the generator this week but last night I pulled off the brush cover and then looked at the brushes and commutator and they look decent. It looks like they both could use a cleaning so I will do that today. Another thing I would like to point out is that the post that connects to the generator is kind of wobbly. Is that an issue? Thanks, Jacob Mangold

The first thing I would is to clean up the armature. Besides that it’s time to rebuild your generator going by the looks of it. The loose post can’t be good in the long run. Do the simple things first and cleaning up the armature is one of them. It can look like it’s clean but a clean up with fine sandpaper will do wonders.

That rubber insulator at the generator post is probably just as old as the car, where it's dried out and is crumbly. You don't want to have that post ground out on the generator casing. Thinking that the post and the metal washers and the terminal nuts can be cleaned up and reused you can get the rubber insulator, along with the insulating gasket for the post, from Gaslight Auto parts in Ohio. ..... They also have replacement front and rear ball bearing assemblies that are lubricated for life...... .......... If you do change your mind about replacing parts in your generator be sure for total satisfaction if you do purchase a generator make sure it's a total rebuilt generator with new field coils, rewound armature assembly, rebuilt brush holder assembly, permanently lubricated ball bearings, .... Not just something that's been repainted and called rebuilt.

When I first bought my car, the literal fireworks coming out of the generator were impressive as hell. Not knowing any better I got a "rebuilt" gen from one of the 'vendors' and it only lasted a short time.... which led me to my current vocation.

John and Robert are spot on with their advice... Id also point out that TBay and other websites (and some vendors) are littered with cheap starters and generators labeled "rebuilt". Rehabbed brushes, rewrapped field coils and a coat of paint just don't cut it. Not over the long term.

Langs also carries most of the parts needed to successfully rebuild gens as do some other vendors. Personally, I have had extremely good luck rehabbing most (but not all) armatures. After doing 100's of them, I generally know when I see a good one and I know how to clean them up so they have the absolute best chance of lasting - it's the only way I can offer a 1 yr warranty on my units, otherwise I'd be constantly replacing them and go broke.

HOWEVER, if you never want another problem, a rewound armature is the only way to go. But they are spendy. Langs sells them for $283, my cost isn't much better. It's a labor intensive process and you have to have a specialized winding machine that does it. I have 5 left out of 10 I started with so 5 folks over the years never want to have issues ever again. Everyone else will likely be back at some point down the road - think of it like how often modern (post 1950's) alternators fail, but much worse. It's really hard to estimate how long rehabbed, used armatures will last. Too many factors influence it. How many hours on it, how many amps is it set to charge for, does it get wet, just how good is the 100 year old lacquer insulating the wires, and MANY other factors. Of the couple hundred or so gens I've sold over the years, I've only had to replace 2 or 3 within a year due to an armature failing. Not bad odds, but again, rehabbing the armature correctly takes time and skill. Also, I never rewrap field coils and always use new ones. Old, crusty, rewrapped field coils just don't do well over time. I used to do it, but never again...

Generators can sometimes be quite tricky. I throw more f-bombs in my shop coaxing rebuilt generators to life than anything else. I have a HUGE pile of bad armatures waiting to be rewound when the world's supply of usable armatures is ultimately gone forever.

As always, Your Mileage Will Vary.

Jeff

Best info Jeff

Literally, my hat is off to all who toil with Model T generators. Myself, I've lost a bunch of religion and hair off of my head trouble shooting, rebuilding and financing futile endeavors to reliably "wheeze" a few blessed volts out of these profoundly obsolete hunks of crap (sorry for the unkind reference). Strict adherence to originality is an admirable endeavor, however sanity needs to prevail at some point. Reluctantly I installed an alternator (obtained from Lang's) a year ago. Since then my hair has grown back, I have enjoyed peace, tranquility and been renewed spiritually.

I hear how horrible they are to rebuild and how temperamental they are, but honestly for the 2 years or so that I was remanufacturing them, there didn't seem to be any mystery or difficulty. If you know how to do the work, you know how to do the work. I don't know air conditioning very well and suppose I'd struggle with fixing one, but for the guy who does it, it's no big deal. Neither are generators, if you know what you're doing. About the only really big "gotcha" is the first time you buy a field coil which was formed backwards and will only operate correctly if you do not have the wires crossed. That will stump you for a good while until you realize it.

I won't do them anymore because not enough folks care enough to keep the car original or seek out people who are competent and can fix what everyone now believes is "unfixable". Spend enough money often enough on Mitsubishi crap, and there in fact won't be anyone left who can or will fix them correctly.

it can be done

but not by me anymore

If Jeff can make it worth his time, then good deal. Spend your money with him and keep the knowledge and the hobby alive.

from days long past:

I guess I’ve been lucky rebuilding the generators on two of my T’s. There are enough ‘how to’ posts on the forum to figure it out and the MTFCA electrical system booklet for ModelT’s are a real help.

I’ve used the above plus being raised in the country on our farm fixing tractors, farm equipment and etc helps too.

With the easy availability of T generator parts, getting the parts you might need makes it fairly easy. If I ever need any advice it’s usually found on past forum posts.

Wow Scott! You even issued green tags with your reconditioned generators?

Man, that’s some serious stuff! I’m impressed!

Thank you Ed

to get them sold, they had to be priced to the market...I found that I was either too slow or thought too highly of my hourly worth, one or the other, and just couldn't keep doing them. That was early in my "gee, I want to be a supplier to the hobby" phase. I've since realized that to make it worth while, there was no point doing something lots of people could do (at least at that time), and focused on things that almost no one else could or wanted to do.

Since you can't really tell what's inside of one of these things, I always felt that attention to detail was one visible clue to quality - I never wanted a customer to wonder what exactly it was that they were buying

My hat is off to folks who can grind this stuff out day after day - I'm just not wired like that

I’ve got an update and it’s good. My generator does make charge but not at idle. When you give it some gas, it jumps to 6 amps on the amp meter. I put a video showing my amp meter on my YouTube: https://youtube.com/shorts/tcJTUgIYdkg?feature=share
Since I’ve now confirmed that it makes charge, this must be an adjustment issue? What do you guys think?

Thank You, Jacob Mangold

Generators do not normally charge at engine idle speed.

A T generator might be expected to show some charge at a road speed of 10 to 12 MPH in high gear, and about 1/3 that speed in low gear.

A TT, being lower geared, would show a charge at lower road speeds, but not at engine idle.

If your lights, or any other accessory, are on, you would probably need to go faster to show a charge, and if you have your lights on with high output light bulbs, you may never see a charge indicated as long as the lights, or any other accessory that draws 6 tp 8 amps or more are switched on.

A T engine in good condition can easily idle at 300 to 400 RPM. The generator cannot develop enough power at those speeds to close the cutout.

Generator output peaks at around 1200 engine RPM and will actually fall off some at higher engine speeds.

Low idle wont produce a net voltage gain over the battery voltage. Thats when you will see a positive amp reading. If you have a mechanical cutout it may not be closing until you reach a higher voltage generation above when it should. The generator, it self is fine.

Jacob,
I concur w/ these folks, your generator is fine! Go driving!
Jeff

Good start for an enjoyable ride